"Salmon leaping" by "openpad" on Flickr

Using public #git sources in private projects

The last post I made was about using submodules to work with code that is being developed, either in isolation from other aspects of a project, or so components can be reused without requiring lots of copy-and-paste activities. It was inspired by a question from a colleague. After asking a few more questions, it turns out that may be what that colleague needed was to consume code from other repositories and store them in their own project.

In this case, I’ve created two repositories, both on GitHub (which will both be removed by the time this post is published) called JonTheNiceGuy/Git_Demo (the “upstream”, open source project) and JonTheNiceGuy-Inc/Git_Demo (the private project, referred to as “mine”).

Getting the “Open Source” project started

Here we have a simple repository, showing the README file for the project (which is likely, in the real world, to show what license that code has been released under, some explaination on what it’s for, etc.) and the actual data source. In this demo, the data source is a series of numbers, showing the decimal number in the first column, the binary representation of that number in the second column, and the hexedecimal representation in the third column.

Our “upstream” repository, showing the README.md file and the data source we want to use.
The data source itself. Note, I forgot to take a screen shot of this file, so I’ve had to “go back to a previous commit” to collect this particular image.

Elsewhere in the world, a private project has started! It’s going to use this data source as some element of this project, and to ensure that the code they’re relying on doesn’t go away, they create their own repository which this code will go into.

Preparing the private project

If both repositories are using GitHub, or if both repositories are using GitLab, then you should be able to “just” Fork the repository, using the “Fork” button in the top right corner:

The “Fork” button

And then select the organisation or account to place the forked repo into.

A list of potential targets to fork the repository into. Your view may differ if you are part of less organisations.

Gitlab has a similar workflow – they have a similar “fork” button, but the list of potential targets is different (but still works the same way).

Gitlab’s list of potential targets to fork the repository into.

Note that you can’t “easily” fork between different Version Control Services! To do something similar, you need to create a new repository in the target service, and then, run some commands to move the code over.

The screen you see immediately after you’ve created a new project – here I’ve created it in the “JonTheNiceGuy-Inc” Organisation. You can see the “quick setup” panel which has the URL to use for the repository.
Here we see the results of running five commands, which are: git clone <url> ; cd <target-dir> ; git remote rename origin upstream ; git remote add mine <url> ; git push –set-upstream mine main

If you’re using the command line method, here’s the commands you issue:

  • git clone http://service/user/repo – This command clones the repository from your service of choice to your local file system. It usually places it into the name of the repository you specified. In this case, “repo”, but in the above context (cloning from Git_Demo.git) it goes into “Git_Demo”. Note, HTTP(S) isn’t the only git transport, another common one is SSH, so if you prefer using SSH instead of HTTP, the URL in this case will be something like git@service:user/repo or service:user/repo. If you’re using submodules, however, I’d strongly recommend using HTTP(S) over SSH for at least the initial pull, as this is much easier for clients to navigate.
  • cd repo – Move into the directory where the cloned repository has been placed.
  • OPTIONAL: git remote rename origin upstream – Rename the remote source of the repository. By default, when you git clone or use git submodule add, the name of the remote resource is called “origin”. I prefer to give a descriptive name for my remote sources, so using “upstream” makes more sense to me. In later commands, I’ll use the remote name “upstream” again. If you don’t want to run this command, and leave the remote name as “origin”, you’ll just have to remember to change it back to “origin”.
  • git remote add mine http://new-service/user/repo – this adds a new remote source, to which you can push new commits, or pull code from your peers. Again, like in the git clone command above, you may use another URL format instead of HTTP(S). You may want to use a different name for the new remote, but again, I tend to prefer “mine” for anything I’m personally working on.
  • git push --set-upstream mine main – This sends the entire commit tree for the branch you’re currently on to your remote source.
Once we’ve run the git push, you can now see that the code has all been pushed to your private project.
Issuing a git log command, shows the current tip on the branch “main” in the “upstream” repository is equal to the current tip on the branch “main” in the “mine” repository, as well as the tip of the “main” repository locally.

Making your local changes

So, while you could just keep using just the upstream project’s code (and doing the above groundwork is good practice to keep you from putting yourself into the situation that the NPM world got into with “left-pad”). What’s more likely is that you want to make your own, local changes to this repository. I’ve done this in the past where I wanted to demonstrate a software build using a public machine image, but internally at work we used our own images. Using this method, I can consume the code I’ve created in public, and just update the assets we use at work.

In this example, let’s update that data file. I’ve added two new lines, “115” (and it’s binary/hex representations) and “132”. I can use the git diff command to confirm the changes I want to make – it’s all good!

Next, I stage the changes with git add, use git commit to write it to the branch, and git push to push it up to my repository. This is all fairly standard stuff in the Git world.

Here we make a change to the data source, confirm there is a difference, add and commit it, and then push it to our default branch (mine/main).

When I then check the git log, we see that there’s a divergence, between my local main branch and the upstream main branch. You could also use git log -p to see the exact code changes, if you wanted… but we know what’s changed already.

The git log, showing that we have a “local” change from the “upstream” source, and that we’ve pushed that local change to the “mine” source.

Bringing data from the upstream source

Oh joy! The upstream project (“JonTheNiceGuy” not “JonTheNiceGuy-Inc”) have updated their Git_Demo repository – they’ve had the audacity to add three new numbers – 9, 10 and 15 – to the data source.

The patch that was applied to this branch. We can check the difference here before we try to do anything with it! It’s something we want!

Well, actually we want to use that data, so let’s start bringing it in. We use the git pull command.

The git pull command, with the remote source (“upstream”) and the branch (“main”) to use.

Because this makes a change to a file that you’ve amended as part of your work, it can’t perform a “Fast forward” of these changes, so Git has to perform a merge commit. This means there’s a new commit in the log, so it’s clear that we’ve updated files because of this merge.

If there were a conflict in this file (which, fortunately, there isn’t!) you’d also be prompted to fix the merge conflicts too. This is a bit bigger than what I’m trying to explain, so instead, I’ll link to a tutorial by Atlassian on merge conflicts. You may also want to take a quick look at the rebasing page on the Git Project’s documentation site, and see whether this might have made your life easier in the case of a conflict!

Anyway, let’s use the default merge message.

The default message when performing a git pull where the change can’t be fast-forwarded.

Once the merge message is done, the merge completes. Yey!

We successfully merged our change, and it’s now part of our local tree

And to prove it, we can now see that we have all the changes from the upstream (commits starting 3b75eb, 8ad9ae, 8bdcae and the new one at a64de2) and our local changes (starting 02e40e).

Because we performed a merge, not a fast forward, our local branch is at a different commit than either of our remote sources – the commit starting 6f4db6 is on our local version, “upstream” is at a64de2 and “mine” is at 02e40e. So we need to fix at least our “mine/main” branch. We do this with a git push.

We do our git push here to get the code into our “mine/main” branch.

And now we can see the git log on our service.

The list of commits on Github for our “mine/main” branch.

And locally, we can see that the remote state has changed too. Let’s look at that git log again.

The result of the git log command on our local machine, showing the new position of the pointers for “upstream/main”, “mine/main” and the local “main” branches.

We can also look at the git blame on the service.

The git blame screen on GitHub, showing who made the various commits.

Or on our local machine.

git blame run locally, showing the commit reference, the author, the date and time of the commit, and the line number, followed by the line in question.

Featured image is β€œSalmon leaping” by β€œopenpad” on Flickr and is released under a CC-BY license.

"Stockholms Stadsbibliotek" by "dilettantiquity" on Flickr

Terraform templates with Maps

For a project I’m working on, I needed to define a list of ports, and set some properties on some of them. In the Ansible world, you’d use statements like:

{% if data.somekey is defined %}something {{ data.somekey }}{% endif %}

or

{{ data.somekey | default('') }}

In a pinch, you can also do this:

{{ (data | default({}) ).somekey | default('') }}

With Terraform, I was finding it much harder to work out how to find whether a value as part of a map (the Terraform term for a Dictionary in Ansible terms, or an Associative Array in PHP terms), until I stumbled over the Lookup function. Here’s how that looks for just a simple Terraform file:

output "test" {
    value = templatefile(
        "template.tmpl",
        {
            ports = {
                "eth0": {"ip": "192.168.1.1/24", "name": "public"}, 
                "eth1": {"ip": "172.16.1.1/24", "name": "protected"}, 
                "eth2": {"ip": "10.1.1.1/24", "name": "management", "management": true}, 
                "eth3": {}
            },
            management = "1"
        }
    )
}

And the template that goes with that?

%{ for port, data in ports ~}
Interface: ${port}%{ if lookup(data, "name", "") != ""}
Alias: ${ lookup(data, "name", "") }%{ endif }
Services: ping%{ if lookup(data, "management", false) == true } ssh https%{ endif }
IP: ${ lookup(data, "ip", "Not Defined") }

%{ endfor }

This results in the following output:

C:\tf>terraform.exe apply -auto-approve

Apply complete! Resources: 0 added, 0 changed, 0 destroyed.

Outputs:

test = Interface: eth0
Alias: public
Services: ping
IP: 192.168.1.1/24

Interface: eth1
Alias: protected
Services: ping
IP: 172.16.1.1/24

Interface: eth2
Alias: management
Services: ping ssh https
IP: 10.1.1.1/24

Interface: eth3
Services: ping
IP: Not Defined

Naturally, using this in your own user-data or Custom Data field will probably make more sense than just writing it to “output” 😁

Featured image is β€œStockholms Stadsbibliotek” by β€œdilettantiquity” on Flickr and is released under a CC-BY-SA license.

"Sydney Observatory I" by "Newtown grafitti" on Flickr

Using Feature Flags in Terraform with Count Statements

In a project I’m working on in Terraform, I’ve got several feature flags in a module. These flags relate to whether this module should turn on a system in a cloud provider, or not, and looks like this:

variable "turn_on_feature_x" {
  description = "Setting this to 'yes' will enable Feature X. Any other value will disable it. (Default 'yes')"
  value = "yes"
}

variable "turn_on_feature_y" {
  description = "Setting this to 'yes' will enable Feature Y. Any other value will disable it. (Default 'no')"
  value = "no"
}

When I call the module, I then can either leave the feature with the default values, or selectively enable or disable them, like this:

module "region1" {
  source = "./my_module"
}

module "region2" {
  source = "./my_module"
  turn_on_feature_x = "no"
  turn_on_feature_y = "yes"
}

module "region3" {
  source = "./my_module"
  turn_on_feature_y = "yes"
}

module "region4" {
  source = "./my_module"
  turn_on_feature_x = "no"
}

# Result:
# region1 has X=yes, Y=no
# region2 has X=no, Y=yes
# region3 has X=yes, Y=yes
# region4 has X=no, Y=no

When I then want to use the feature, I have to remember a couple of key parts.

  1. Normally this feature check is done with a “count” statement, and the easiest way to use this is to use the ternary operator to check values and return a “1” or a “0” for if you want the value used.

    Ternary operators look like this: var.turn_on_feature_x == "yes" ? 1 : 0 which basically means, if the value of the variable turn_on_feature_x is set to “yes”, then return 1 otherwise return 0.

    This can get a bit complex, particularly if you want to check several flags a few times, like this: var.turn_on_feature_x == "yes" ? var.turn_on_feature_y == "yes" ? 1 : 0 : 0. I’ve found that wrapping them in brackets helps to understand what you’re getting, like this:

    (
      var.turn_on_feature_x == "yes" ?
      (
        var.turn_on_feature_y == "yes" ?
        1 :
        0
      ) :
      0
    )
  2. If you end up using a count statement, the resulting value must be treated as an 0-indexed array, like this: some_provider_service.my_name[0].result

    This is because, using the count value says “I want X number of resources”, so Terraform has to treat it as an array, in case you actually wanted 10 instead of 1 or 0.

Here’s an example of that in use:

resource "aws_guardduty_detector" "Region" {
  count = var.enable_guardduty == "yes" ? 1 : 0
  enable = true
}

resource "aws_cloudwatch_event_rule" "guardduty_finding" {
  count = (var.enable_guardduty == "yes" ? (var.send_guardduty_findings_to_sns == "yes" ? 1 : (var.send_guardduty_findings_to_sqs == "yes" ? 1 : 0)) : 0)
  name = "${data.aws_caller_identity.current.account_id}-${data.aws_region.current.name}-${var.sns_guardduty_finding_suffix}"
  event_pattern = <<PATTERN
{
  "source": [
    "aws.guardduty"
  ],
  "detail-type": [
    "GuardDuty Finding"
  ]
}
PATTERN
}

resource "aws_cloudwatch_event_target" "sns_guardduty_finding" {
  count = (var.enable_guardduty == "yes" ? (var.send_guardduty_findings_to_sns == "yes" ? 1 : 0) : 0)
  rule = aws_cloudwatch_event_rule.guardduty_finding[0].name
  target_id = aws_sns_topic.guardduty_finding[0].name
  arn = aws_sns_topic.guardduty_finding[0].arn
}

resource "aws_cloudwatch_event_target" "sqs_guardduty_finding" {
  count = (var.enable_guardduty == "yes" ? (var.send_guardduty_findings_to_sqs == "yes" ? 1 : 0) : 0)
  rule = aws_cloudwatch_event_rule.guardduty_finding[0].name
  target_id = "SQS"
  arn = aws_sqs_queue.guardduty_finding[0].arn
}

One thing that bit me rather painfully around this was that if you change from an uncounted resource, like this:

resource "some_tool" "this" {
  some_setting = 1
}

To a counted resource, like this:

resource "some_tool" "this" {
  count = var.some_tool == "yes" ? 1 : 0
  some_setting = 1
}

Then, Terraform will promptly destroy some_tool.this to replace it with some_tool.this[0], because they’re not the same referenced thing!

Fun, huh? 😊

Featured image is β€œSydney Observatory I” by β€œNewtown grafitti” on Flickr and is released under a CC-BY license.

"Kelvin Test" by "Eelke" on Flickr

In Ansible, determine the type of a value, and casting those values to other types

TL;DR? It’s possible to work out what type of variable you’re working with in Ansible. The in-built filters don’t always do quite what you’re expecting. Jump to the “In Summary” heading for my suggestions.

One of the things I end up doing quite a bit with Ansible is value manipulation. I know it’s not really normal, but… well, I like rewriting values from one type of a thing to the next type of a thing.

For example, I like taking a value that I don’t know if it’s a list or a string, and passing that to an argument that expects a list.

Doing it wrong, getting it better

Until recently, I’d do that like this:

- debug:
    msg: |-
      {
        {%- if value | type_debug == "string" or value | type_debug == "AnsibleUnicode" -%}
           "string": "{{ value }}"
        {%- elif value | type_debug == "dict" or value | type_debug == "ansible_mapping" -%}
          "dict": {{ value }}
        {%- elif value | type_debug == "list" -%}
          "list": {{ value }}
        {%- else -%}
          "other": "{{ value }}"
        {%- endif -%}
      }

But, following finding this gist, I now know I can do this:

- debug:
    msg: |-
      {
        {%- if value is string -%}
           "string": "{{ value }}"
        {%- elif value is mapping -%}
          "dict": {{ value }}
        {%- elif value is iterable -%}
          "list": {{ value }}
        {%- else -%}
          "other": "{{ value }}"
        {%- endif -%}
      }

So, how would I use this, given the context of what I was saying before?

- assert:
    that:
    - value is string
    - value is not mapping
    - value is iterable
- some_module:
    some_arg: |-
      {%- if value is string -%}
        ["{{ value }}"]
      {%- else -%}
        {{ value }}
      {%- endif -%}

More details on finding a type

Why in this order? Well, because of how values are stored in Ansible, the following states are true:

⬇️Type \ ➑️Checkis iterableis mappingis sequenceis string
a_dict (e.g. {})βœ”οΈβœ”οΈβœ”οΈβŒ
a_list (e.g. [])βœ”οΈβŒβœ”οΈβŒ
a_string (e.g. “”)βœ”οΈβœ”οΈβœ”οΈβœ”οΈ
A comparison between value types

So, if you were to check for is iterable first, you might match on a_list or a_dict instead of a_string, but string can only match on a_string. Once you know it can’t be a string, you can check whether something is mapping – again, because a mapping can match either a_string or a_dict, but it can’t match a_list. Once you know it’s not that, you can check for either is iterable or is sequence because both of these match a_string, a_dict and a_list.

Likewise, if you wanted to check whether a_float and an_integer is number and not is string, you can check these:

⬇️Type \ ➑️Checkis floatis integeris iterableis mappingis numberis sequenceis string
a_floatβœ”οΈβŒβŒβŒβœ”οΈβŒβŒ
an_integerβŒβœ”οΈβŒβŒβœ”οΈβŒβŒ
A comparison between types of numbers

So again, a_float and an_integer don’t match is string, is mapping or is iterable, but they both match is number and they each match their respective is float and is integer checks.

How about each of those (a_float and an_integer) wrapped in quotes, making them a string? What happens then?

⬇️Type \ ➑️Checkis floatis integeris iterableis mappingis numberis sequenceis string
a_float_as_stringβŒβŒβœ”οΈβŒβŒβœ”οΈβœ”οΈ
an_integer_as_stringβŒβŒβœ”οΈβŒβŒβœ”οΈβœ”οΈ
A comparison between types of numbers when held as a string

This is somewhat interesting, because they look like a number, but they’re actually “just” a string. So, now you need to do some comparisons to make them look like numbers again to check if they’re numbers.

Changing the type of a string

What happens if you cast the values? Casting means to convert from one type of value (e.g. string) into another (e.g. float) and to do that, Ansible has three filters we can use, float, int and string. You can’t cast to a dict or a list, but you can use dict2items and items2dict (more on those later). So let’s start with casting our group of a_ and an_ items from above. Here’s a list of values I want to use:

---
- hosts: localhost
  gather_facts: no
  vars:
    an_int: 1
    a_float: 1.1
    a_string: "string"
    an_int_as_string: "1"
    a_float_as_string: "1.1"
    a_list:
      - item1
    a_dict:
      key1: value1

With each of these values, I returned the value as Ansible knows it, what happens when you do {{ value | float }} to cast it as a float, as an integer by doing {{ value | int }} and as a string {{ value | string }}. Some of these results are interesting. Note that where you see u'some value' means that Python converted that string to a Unicode string.

⬇️Value \ ➑️Castvaluevalue when cast as floatvalue when cast as integervalue when cast as string
a_dict{“key1”: “value1”}0.00“{u’key1′: u’value1′}”
a_float1.11.11“1.1”
a_float_as_string“1.1”1.11“1.1”
a_list[“item1”]0.00“[u’item1′]”
a_string“string”0.00“string”
an_int111“1”
an_int_as_string“1”11“1”
Casting between value types

So, what does this mean for us? Well, not a great deal, aside from to note that you can “force” a number to be a string, or a string which is “just” a number wrapped in quotes can be forced into being a number again.

Oh, and casting dicts to lists and back again? This one is actually pretty clearly documented in the current set of documentation (as at 2.9 at least!)

Checking for miscast values

How about if I want to know whether a value I think might be a float stored as a string, how can I check that?

{{ vars[var] | float | string == vars[var] | string }}

What is this? If I cast a value that I think might be a float, to a float, and then turn both the cast value and the original into a string, do they match? If I’ve got a string or an integer, then I’ll get a false, but if I have actually got a float, then I’ll get true. Likewise for casting an integer. Let’s see what that table looks like:

⬇️Type \ ➑️Checkvalue when cast as floatvalue when cast as integervalue when cast as string
a_floatβœ”οΈβŒβœ”οΈ
a_float_as_stringβœ”οΈβŒβœ”οΈ
an_integerβŒβœ”οΈβœ”οΈ
an_integer_as_stringβŒβœ”οΈβœ”οΈ
A comparison between types of numbers when cast to a string

So this shows us the values we were after – even if you’ve got a float (or an integer) stored as a string, by doing some careful casting, you can confirm they’re of the type you wanted… and then you can pass them through the right filter to use them in your playbooks!

Booleans

Last thing to check – boolean values – “True” or “False“. There’s a bit of confusion here, as a “boolean” can be: true or false, yes or no, 1 or 0, however, is true and True and TRUE the same? How about false, False and FALSE? Let’s take a look!

⬇️Value \ ➑️Checktype_debug is booleanis numberis iterableis mappingis stringvalue when cast as boolvalue when cast as stringvalue when cast as integer
yesboolβœ”οΈβœ”οΈβŒβŒβŒTrueTrue1
YesAnsibleUnicodeβŒβŒβœ”οΈβŒβœ”οΈFalseYes0
YESAnsibleUnicodeβŒβŒβœ”οΈβŒβœ”οΈFalseYES0
“yes”AnsibleUnicodeβŒβŒβœ”οΈβŒβœ”οΈTrueyes0
“Yes”AnsibleUnicodeβŒβŒβœ”οΈβŒβœ”οΈTrueYes0
“YES”AnsibleUnicodeβŒβŒβœ”οΈβŒβœ”οΈTrueYES0
trueboolβœ”οΈβœ”οΈβŒβŒβŒTrueTrue1
Trueboolβœ”οΈβœ”οΈβŒβŒβŒTrueTrue1
TRUEboolβœ”οΈβœ”οΈβŒβŒβŒTrueTrue1
“true”AnsibleUnicodeβŒβŒβœ”οΈβŒβœ”οΈTruetrue0
“True”AnsibleUnicodeβŒβŒβœ”οΈβŒβœ”οΈTrueTrue0
“TRUE”AnsibleUnicodeβŒβŒβœ”οΈβŒβœ”οΈTrueTRUE0
1intβŒβœ”οΈβŒβŒβŒTrue11
“1”AnsibleUnicodeβŒβŒβœ”οΈβŒβœ”οΈTrue11
noboolβœ”οΈβœ”οΈβŒβŒβŒFalseFalse0
Noboolβœ”οΈβœ”οΈβŒβŒβŒFalseFalse0
NOboolβœ”οΈβœ”οΈβŒβŒβŒFalseFalse0
“no”AnsibleUnicodeβŒβŒβœ”οΈβŒβœ”οΈFalseno0
“No”AnsibleUnicodeβŒβŒβœ”οΈβŒβœ”οΈFalseNo0
“NO”AnsibleUnicodeβŒβŒβœ”οΈβŒβœ”οΈFalseNO0
falseboolβœ”οΈβœ”οΈβŒβŒβŒFalseFalse0
Falseboolβœ”οΈβœ”οΈβŒβŒβŒFalseFalse0
FALSEboolβœ”οΈβœ”οΈβŒβŒβŒFalseFalse0
“false”AnsibleUnicodeβŒβŒβœ”οΈβŒβœ”οΈFalsefalse0
“False”AnsibleUnicodeβŒβŒβœ”οΈβŒβœ”οΈFalseFalse0
“FALSE”AnsibleUnicodeβŒβŒβœ”οΈβŒβœ”οΈFalseFALSE0
0intβŒβœ”οΈβŒβŒβŒFalse00
“0”AnsibleUnicodeβŒβŒβœ”οΈβŒβœ”οΈFalse00
Comparisons between various stylings of boolean representations

So, the stand out thing for me here is that while all the permutations of string values of the boolean representations (those wrapped in quotes, like this: "yes") are treated as strings, and shouldn’t be considered as “boolean” (unless you cast for it explicitly!), and all non-string versions of true, false, and no are considered to be boolean, yes, Yes and YES are treated differently, depending on case. So, what would I do?

In summary

  • Consistently use no or yes, true or false in lower case to indicate a boolean value. Don’t use 1 or 0 unless you have to.
  • If you’re checking that you’re working with a string, a list or a dict, check in the order string (using is string), dict (using is mapping) and then list (using is sequence or is iterable)
  • Checking for numbers that are stored as strings? Cast your string through the type check for that number, like this: {% if value | float | string == value | string %}{{ value | float }}{% elif value | int | string == value | string %}{{ value | int }}{% else %}{{ value }}{% endif %}
  • Try not to use type_debug unless you really can’t find any other way. These values will change between versions, and this caused me a lot of issues with a large codebase I was working on a while ago!

Run these tests yourself!

Want to run these tests yourself? Here’s the code I ran (also available in a Gist on GitHub), using Ansible 2.9.10.

---
- hosts: localhost
  gather_facts: no
  vars:
    an_int: 1
    a_float: 1.1
    a_string: "string"
    an_int_as_string: "1"
    a_float_as_string: "1.1"
    a_list:
      - item1
    a_dict:
      key1: value1
  tasks:
    - debug:
        msg: |
          {
          {% for var in ["an_int", "an_int_as_string","a_float", "a_float_as_string","a_string","a_list","a_dict"] %}
            "{{ var }}": {
              "type_debug": "{{ vars[var] | type_debug }}",
              "value": "{{ vars[var] }}",
              "is float": "{{ vars[var] is float }}",
              "is integer": "{{ vars[var] is integer }}",
              "is iterable": "{{ vars[var] is iterable }}",
              "is mapping": "{{ vars[var] is mapping }}",
              "is number": "{{ vars[var] is number }}",
              "is sequence": "{{ vars[var] is sequence }}",
              "is string": "{{ vars[var] is string }}",
              "value cast as float": "{{ vars[var] | float }}",
              "value cast as integer": "{{ vars[var] | int }}",
              "value cast as string": "{{ vars[var] | string }}",
              "is same when cast to float": "{{ vars[var] | float | string == vars[var] | string }}",
              "is same when cast to integer": "{{ vars[var] | int | string == vars[var] | string }}",
              "is same when cast to string": "{{ vars[var] | string == vars[var] | string }}",
            },
          {% endfor %}
          }
---
- hosts: localhost
  gather_facts: false
  vars:
    # true, True, TRUE, "true", "True", "TRUE"
    a_true: true
    a_true_initial_caps: True
    a_true_caps: TRUE
    a_string_true: "true"
    a_string_true_initial_caps: "True"
    a_string_true_caps: "TRUE"
    # yes, Yes, YES, "yes", "Yes", "YES"
    a_yes: yes
    a_yes_initial_caps: Tes
    a_yes_caps: TES
    a_string_yes: "yes"
    a_string_yes_initial_caps: "Yes"
    a_string_yes_caps: "Yes"
    # 1, "1"
    a_1: 1
    a_string_1: "1"
    # false, False, FALSE, "false", "False", "FALSE"
    a_false: false
    a_false_initial_caps: False
    a_false_caps: FALSE
    a_string_false: "false"
    a_string_false_initial_caps: "False"
    a_string_false_caps: "FALSE"
    # no, No, NO, "no", "No", "NO"
    a_no: no
    a_no_initial_caps: No
    a_no_caps: NO
    a_string_no: "no"
    a_string_no_initial_caps: "No"
    a_string_no_caps: "NO"
    # 0, "0"
    a_0: 0
    a_string_0: "0"
  tasks:
    - debug:
        msg: |
          {
          {% for var in ["a_true","a_true_initial_caps","a_true_caps","a_string_true","a_string_true_initial_caps","a_string_true_caps","a_yes","a_yes_initial_caps","a_yes_caps","a_string_yes","a_string_yes_initial_caps","a_string_yes_caps","a_1","a_string_1","a_false","a_false_initial_caps","a_false_caps","a_string_false","a_string_false_initial_caps","a_string_false_caps","a_no","a_no_initial_caps","a_no_caps","a_string_no","a_string_no_initial_caps","a_string_no_caps","a_0","a_string_0"] %}
            "{{ var }}": {
              "type_debug": "{{ vars[var] | type_debug }}",
              "value": "{{ vars[var] }}",
              "is float": "{{ vars[var] is float }}",
              "is integer": "{{ vars[var] is integer }}",
              "is iterable": "{{ vars[var] is iterable }}",
              "is mapping": "{{ vars[var] is mapping }}",
              "is number": "{{ vars[var] is number }}",
              "is sequence": "{{ vars[var] is sequence }}",
              "is string": "{{ vars[var] is string }}",
              "is bool": "{{ vars[var] is boolean }}",
              "value cast as float": "{{ vars[var] | float }}",
              "value cast as integer": "{{ vars[var] | int }}",
              "value cast as string": "{{ vars[var] | string }}",
              "value cast as bool": "{{ vars[var] | bool }}",
              "is same when cast to float": "{{ vars[var] | float | string == vars[var] | string }}",
              "is same when cast to integer": "{{ vars[var] | int | string == vars[var] | string }}",
              "is same when cast to string": "{{ vars[var] | string == vars[var] | string }}",
              "is same when cast to bool": "{{ vars[var] | bool | string == vars[var] | string }}",
            },
          {% endfor %}
          }

Featured image is β€œKelvin Test” by β€œEelke” on Flickr and is released under a CC-BY license.

"html tattoo" by "webmove" on Flickr

Writing with Commonmark/Markdown formatting

I’m starting to write some documentation, and I realised that I’ve not documented how I write with Markdown. So, let’s make some notes here :) This is largely drawn from the CommonMark Markdown Cheat Sheet, as well as my own experiences.

I’ll use the terms “Markdown” and “Commonmark” interchangeably, but really I’m talking about the “Commonmark” implementation of Markdown, as Markdown is just a “way of doing things”, whereas Commonmark is a specification to standardise how Markdown is done.

Late edit, 2020-06-24: My colleague, Simon Partridge, who writes the “Tech Snippets” round up of interesting content, pointed me to a Markdown Tutorial that he recommends. I’ve added two “Late Edit” comments below, in the Lists section and a new section called “Soft Breaks”, featuring stuff I’d not come across before that was on the Markdown Tutorial. It’s well worth a look! Dave Lee, the producer on the podcast I co-host, podcaster in his own right, and all-round-lovely-guy, also noted that the Walt Disney quote I included below wasn’t quite formatted right. I’ve fixed this, and added another example for clarity.

Normal text

This is normal text, you might know it in HTML as “paragraph” mode, or <p>some text</p>.

In your word processor, this is the default styled text that you start with.

In Markdown and Commonmark, line lengths don’t matter, you can just keep writing and writing and writing, or you can type 40 characters, and put a single new line in, and it’ll keep the text on the same line, like this:

In your word processor, this is the default styled
text that you start with.

In Markdown and Commonmark, line lengths don't matter, you can just keep writing and writing and writing or you can type 40 characters and put a single new line in, and it'll keep the text on the same line, like this:

Links

While a single page of text is often useful, some people find it easier to connect to other documents. In HTML, you would do this by writing something like this: <a hrΠ΅f="http://example.com">Link</a>. In Markdown, you use this format:

You might want to put your [link](http://example.com) in here for later.

This link is in-line for ease of understanding.

This makes it very easy to read in-line where a link is pointing to. It’s also possible to make those links listed elsewhere in the document, by writing something like this:

You might want to put your [link][1] in here for later.

Some documents include links elsewhere in their structure, which is easier
for moving links around your document, while keeping the formatting
structure.

[1]: (http://example.com)

Links can be to absolute URLs (http://example.com/some/page.html), or relative URLs (some/page.html) and can include anchor points (http://example.com/some/page.html#heading-1). They can also link to other protocols, like email (mailto:person@example.org) or ftp (ftp://user:password@192.0.2.1/some/directory/).

Images

Much like the link layout, in HTML an image is inserted with a special tag, in that case, <img src="http://example.com/some/image.png" alt="Some Image">. An image can have an “Alt Tag”, which is text that a screen reader (for people with partial or complete vision loss) can read out. To put an image into a Markdown document, you use the link-style formatting, but add an exclamation mark before it, like this:

![Some Image](http://example.com/some/image.png)
![Some other image][1]

[1]: (relative/paths/work/too.png)

If you want to mix Images and Links, you do that like this:

[![This is an arrow, pointing you to your link](arrow.png)](my_link.html)

Note that here it looks a little complicated, as you’ve got the image identifier (![]()) inside the link identifier ([]()). Again, you could also use some non-inline URLs to clarify that a little, like this:

[![Click here to send an email][email]](mailto:someone@example.net?subject=Enquiry)

[email]: http://example.org/assets/email.png

Headings

You can prefix text with the # symbol and a space to make it a “top level heading”, like my heading for this blog post “Writing with Commonmark/Markdown formatting”, like this:

# Writing with Commonmark/Markdown formatting

Subsequent level headings, from 2 (e.g. “Headings” above) to 6 are written like this:

## Headings

### Now also at level 3

#### And level 4

##### And so on

###### Until level 6

### You can also jump back up levels, if you need to

Typically, you include a line space before and after the heading, just to make it clearer that this is a heading. It’s also possible to use the equals underlining and hyphen underlining to turn a single top level and second level heading, like this:

# Heading 1

is the same as

Heading 1
=========
## Heading 2

is the same as

Heading 2
---------

I’ve not really seen that structure before, but it seems less clear than the symbol-prefix method… I guess it’s just codifying some early practices.

Another benefit to the headings is that they automatically get turned into “anchor tags”, so you can refer to those points elsewhere in your document, like this:

Refer to [our sales literature for more details](#sales-literature).

## Sales Literature

![Our Brochure](brochure.jpg)

Note that the anchor tag in this case is any heading tag (level 1 to 6), turned into lower case, and replacing any spaces with hyphens and removing any other characters.

Emphasis

Aside from the above, you can also use some punctuation to indicate emphasis, like this:

This is *bold* text. As is _this_.

This text is **italicised** instead. This is __too__.

This text is ***both*** bold and italicised. ___Also___ here.
So is __*this*__ and **_this_** and _**this**_ and *__this__*.

Lists (ordered and unordered)

An ordered list looks like this:

1. Go to the shops
  1. Open the door
  2. Walk in
  3. Select products
  4. Pay for products
    1. Use debit or credit card
    2. Enter PIN
  5. Open the door
  6. Exit
2. Go home

and so on. An unordered list looks like this:

* Eggs
* Dairy
  * Milk
  * Cheese
* Meat
  * Pork
    * Ham
    * Bacon
  * Beef

Both of these can be rendered in Markdown using this format:

1. Go to the shops
    1. Open the door
    2. Walk in
    3. Select products
        * Eggs
        * Dairy
            * Milk
2. Go home

Notice that you can nest ordered and unordered lists. You need to provide four spaces when indenting from one level to the next.

If you’re not sure what the numbering will be, you can replace each of the numbers (1., 2., 3. and so on) with a single number, 1. Also, * for the unordered list can be replaced with -. So, the above example could look like this:

1. Go to the shops
    1. Open the door
    1. Walk in
    1. Select products
        - Eggs
        - Dairy
            * Milk
1. Go home

This all depends on what writing style you prefer.

Late Edit: 2020-06-24 If you want to include a more content under the same list item, you can add a new line and indent it by at least one space (and usually to the same indenting level as the bullet point), like this:

1. Go to the shops

   I've found going to Smiths, on the high street best.

   1. Open the door

      Use the handle on the edge of the door.

   1. Walk in
   1. Select products

      Look for items with the best dates. The items you need are as follows:

      - Eggs
      - Dairy
          * Milk

Soft Breaks (Late edit, 2020-06-24)

A soft break, written in HTML as <br>, is signalled in Markdown with two spaces, like this (spaces replaced with . characters):

It.was.a.dark.day..
Bob.had.died.a.sad.death..
All.alone.in.his.fish.tank

This would be rendered like this (italicised to differentiate from the rest of this post):

It was a dark day
Bob had died a sad death
All alone in his fish tank

Quoting text

The way to get started is to quit talking and begin doing.

Walt Disney

People sometimes like to quote other people. In Markdown, we do this by following a long email convention, proceeding the quote with a “chevron” symbol – >, like this:

> The way to get started is to quit talking and begin doing.
> 
> [*Walt Disney*](https://blog.hubspot.com/sales/famous-quotes)

Note that this could also have been written like this:

As Walt Disney once said:

The way to get started is to quit talking and begin doing.

As [Walt Disney](https://blog.hubspot.com/sales/famous-quotes) once said:

> The way to get started is to quit talking and begin doing.

Embedding code

This one I use all the time. Backticks (`) help you embed code, while three backticks (```) start a block of code, like this:

Also, `*` for the unordered list can be replaced with `-`.

```
> The way to get started is to quit talking and begin doing.

[Walt Disney](https://blog.hubspot.com/sales/famous-quotes)
```

Some interpretations of Markdown (notably “Github Flavoured Markdown”) let you signal what type of code you’ve written by adding the language after the first set of three backticks, like this:

```bash
#!/bin/bash
echo "$1"
exit
```

If three backticks don’t work for you, you can instead add four spaces before each line of your code, like this:

    #!/bin/bash
    echo "$1"
    exit

Raw HTML

Sometimes you just can’t do with Markdown what you want to achieve. I’ve notably found this with trying to incorporate several images and figure references in an ordered list, but in those cases, you can always use “raw HTML”. Here’s a list (from the Commonmark Spec as of version 0.29, dated 2019-04-06) of what tags are available to you:

address, article, aside, base, basefont, blockquote, body, caption, center, col, colgroup, dd, details, dialog, dir, div, dl, dt, fieldset, figcaption, figure, footer, form, frame, frameset, h1, h2, h3, h4, h5, h6, head, header, hr, html, iframe, legend, li, link, main, menu, menuitem, nav, noframes, ol, optgroup, option, p, param, section, source, summary, table, tbody, td, tfoot, th, thead, title, tr, track, ul

Given this, here’s what I tend to do:

1. Here's something to do with the following image<br>
![alt text](figure1.png)<br>
*Figure 1 - Some image that is relevant*<br>

Since looking into this further, this is now what I intend to do:

1. Here's something to do with the following image
<figure>![alt text](figure1.png)
<figcaption>*Figure 1 - Some image that is relevant*</figcaption>
</figure>

Tables

Not all Markdown flavours incorporate these, but some do. Trial-and-error is your friend here!

Github Flavoured Markdown supports tables, as do several other Markdown interpreters, but it’s explicitly not in Commonmark.

These are very basic tables, but will work for several cases. In this case, you MUST have a heading row (in my case, the first column has no name, but the second, third and fourth have the text “column” and then the alignment the subsequent rows follow), then a line which indicates the alignment of the row, either left (|---|), right (|--:|) or centre (|:-:|). All subsequent lines must contain all the columns specified. You can’t merge columns or rows, without resorting to HTML table definitions.

|      | Column Left | Column Right | Column Centre |
|------|-------------|-------------:|:-------------:|
| row1 | 1           |            1 |       1       |
| row2 | 2           |            2 |       2       |
| row3 | 3           |            3 |       3       |

In this case, you’ll get the following:

Note that different flavours disagree on whether the alignment of the text inside the rows matters, so while the above text works out OK, the following would also produce exactly the same result:

|      | Column Left | Column Right | Column Centre |
|------|-------------|-------------:|:-------------:|
| row1 | 1           | 1            | 1             |
| row2 | 2           | 2            | 2             |
| row3 | 3           | 3            | 3             |

As would this:

|  | Column Left | Column Right | Column Centre |
|-|-|-:|:-:|
| row1 | 1 | 1 | 1 |
| row2 | 2 | 2 | 2 |
| row3 | 3 | 3 | 3 |

Personally, I’d probably use the longer format divider line to match up to the column heads, but use the shorter format for the rows.

Using Markdown

  • In projects on Github and Gitlab, any file suffixed .md will usually be rendered as a Markdown file. Editing a Markdown file in Github at least will allow you to use the “preview” tab to see the changes. You can also include some Markdown in issues and pull/merge requests. It is not recommended for git logs, and IIRC won’t render it there either.
  • Visual Studio Code will preview Markdown, and has a “linting” extension, called “markdownlint“, that will help identify common issues with Markdown.
  • WordPress’ “Gutenberg” block editor supports using markdown, both for importing content, and for using it to shortcut things like bold, italics, headings and links (in fact, I wrote rather a lot of this using it!).
  • Popular blogging platform Ghost and static site creation tool Jekyll both use Markdown extensively.

Alternatives

  • Naturally, Plain Text is an option :)
  • You might also consider “Restructured Text” (RST) which are popular with open source projects for their documentation.

Featured image is β€œhtml tattoo” by β€œwebmove” on Flickr and is released under a CC-BY license.

β€œNew shoes” by β€œMorgaine” from Flickr

Making Windows Cloud-Init Scripts run after a reboot (Using Terraform)

I’m currently building a Proof Of Value (POV) environment for a product, and one of the things I needed in my environment was an Active Directory domain.

To do this in AWS, I had to do the following steps:

  1. Build my Domain Controller
    1. Install Windows
    2. Set the hostname (Reboot)
    3. Promote the machine to being a Domain Controller (Reboot)
    4. Create a domain user
  2. Build my Member Server
    1. Install Windows
    2. Set the hostname (Reboot)
    3. Set the DNS client to point to the Domain Controller
    4. Join the server to the domain (Reboot)

To make this work, I had to find a way to trigger build steps after each reboot. I was working with Windows 2012R2, Windows 2016 and Windows 2019, so the solution had to be cross-version. Fortunately I found this script online! That version was great for Windows 2012R2, but didn’t cover Windows 2016 or later… So let’s break down what I’ve done!

In your userdata field, you need to have two sets of XML strings, as follows:

<persist>true</persist>
<powershell>
$some = "powershell code"
</powershell>

The first block says to Windows 2016+ “keep trying to run this script on each boot” (note that you need to stop it from doing non-relevant stuff on each boot – we’ll get to that in a second!), and the second bit is the PowerShell commands you want it to run. The rest of this now will focus just on the PowerShell block.

  $path= 'HKLM:\Software\UserData'
  
  if(!(Get-Item $Path -ErrorAction SilentlyContinue)) {
    New-Item $Path
    New-ItemProperty -Path $Path -Name RunCount -Value 0 -PropertyType dword
  }
  
  $runCount = Get-ItemProperty -Path $path -Name Runcount -ErrorAction SilentlyContinue | Select-Object -ExpandProperty RunCount
  
  if($runCount -ge 0) {
    switch($runCount) {
      0 {
        $runCount = 1 + [int]$runCount
        Set-ItemProperty -Path $Path -Name RunCount -Value $runCount
        if ($ver -match 2012) {
          #Enable user data
          $EC2SettingsFile = "$env:ProgramFiles\Amazon\Ec2ConfigService\Settings\Config.xml"
          $xml = [xml](Get-Content $EC2SettingsFile)
          $xmlElement = $xml.get_DocumentElement()
          $xmlElementToModify = $xmlElement.Plugins
          
          foreach ($element in $xmlElementToModify.Plugin)
          {
            if ($element.name -eq "Ec2HandleUserData") {
              $element.State="Enabled"
            }
          }
          $xml.Save($EC2SettingsFile)
        }
        $some = "PowerShell Script"
      }
    }
  }

Whew, what a block! Well, again, we can split this up into a couple of bits.

In the first few lines, we build a pointer, a note which says “We got up to here on our previous boots”. We then read that into a variable and find that number and execute any steps in the block with that number. That’s this block:

  $path= 'HKLM:\Software\UserData'
  
  if(!(Get-Item $Path -ErrorAction SilentlyContinue)) {
    New-Item $Path
    New-ItemProperty -Path $Path -Name RunCount -Value 0 -PropertyType dword
  }
  
  $runCount = Get-ItemProperty -Path $path -Name Runcount -ErrorAction SilentlyContinue | Select-Object -ExpandProperty RunCount
  
  if($runCount -ge 0) {
    switch($runCount) {

    }
  }

The next part (and you’ll repeat it for each “number” of reboot steps you need to perform) says “increment the number” then “If this is Windows 2012, remind the userdata handler that the script needs to be run again next boot”. That’s this block:

      0 {
        $runCount = 1 + [int]$runCount
        Set-ItemProperty -Path $Path -Name RunCount -Value $runCount
        if ($ver -match 2012) {
          #Enable user data
          $EC2SettingsFile = "$env:ProgramFiles\Amazon\Ec2ConfigService\Settings\Config.xml"
          $xml = [xml](Get-Content $EC2SettingsFile)
          $xmlElement = $xml.get_DocumentElement()
          $xmlElementToModify = $xmlElement.Plugins
          
          foreach ($element in $xmlElementToModify.Plugin)
          {
            if ($element.name -eq "Ec2HandleUserData") {
              $element.State="Enabled"
            }
          }
          $xml.Save($EC2SettingsFile)
        }
        
      }

In fact, it’s fair to say that in my userdata script, this looks like this:

  $path= 'HKLM:\Software\UserData'
  
  if(!(Get-Item $Path -ErrorAction SilentlyContinue)) {
    New-Item $Path
    New-ItemProperty -Path $Path -Name RunCount -Value 0 -PropertyType dword
  }
  
  $runCount = Get-ItemProperty -Path $path -Name Runcount -ErrorAction SilentlyContinue | Select-Object -ExpandProperty RunCount
  
  if($runCount -ge 0) {
    switch($runCount) {
      0 {
        ${file("templates/step.tmpl")}

        ${templatefile(
          "templates/rename_windows.tmpl",
          {
            hostname = "SomeMachine"
          }
        )}
      }
      1 {
        ${file("templates/step.tmpl")}

        ${templatefile(
          "templates/join_ad.tmpl",
          {
            dns_ipv4 = "192.0.2.1",
            domain_suffix = "ad.mycorp",
            join_account = "ad\someuser",
            join_password = "SomePassw0rd!"
          }
        )}
      }
    }
  }

Then, after each reboot, you need a new block. I have a block to change the computer name, a block to join the machine to the domain, and a block to install an software that I need.

Featured image is β€œNew shoes” by β€œMorgaine” on Flickr and is released under a CC-BY-SA license.

"Fishing line and bobbin stuck on tree at Douthat State Park" by "Virginia State Parks" on Flickr

Note to self: Linux shell scripts don’t cope well with combined CRLF + LF files… Especially in User-Data / Custom Data / Cloud-Init scripts

This one is more a nudge to myself. On several occasions when building Infrastructure As Code (IAC), I split out a code sections into one or more files, for readability and reusability purposes. What I tended to do, and this was more apparent with the Linux builds than the Windows builds, was to forget to set the line terminator from CRLF to LF.

While this doesn’t really impact Windows builds too much (they’re kinda designed to support people being idiots with line endings now), Linux still really struggles with CRLF endings, and you’ll only see when you’ve broken this because you’ll completely fail to run any of the user-data script.

How do you determine this is your problem? Well, actually it’s a bit tricky, as neither cat, less, more or nano spot this issue. The only two things I found that identified it were file and vi.

The first part of the combined file with mixed line endings. This part has LF termination.
The second part of the combined file with mixed line endings. This part has CRLF termination.
What happens when we cat these two parts into one file? A file with CRLF, LF line terminators obviously!
What the combined file looks like in Vi. Note the blue ^M at the ends of the lines.

So, how to fix this? Assuming you’re using Visual Studio Code;

A failed line-ending clue in Visual Studio Code

You’ll notice this line showing “CRLF” in the status bar at the bottom of Code. Click on that, which brings up a discrete box near the top, as follows:

Oh no, it’s set to “CRLF”. That’s not what we want!

Selecting LF in that box changes the line feeds into LF for this file, but it’s not saved. Make sure you save this file before you re-run your terraform script!

Notice, we’re now using LF endings, but the file isn’t saved.

Fantastic! It’s all worked!

In Nano, I’ve opened the part with the invalid line endings.

Oh no! We have a “DOS Format” file. Quick, let’s fix it!

To fix this, we need to write the file out. Hit Ctrl+O. This tells us that we’re in DOS Format, and also gives us the keyboard combination to toggle “DOS Format” off – it’s Alt+D (In Unix/Linux world, the Alt key is referred to as the Meta key – hence M not A).

This is how we fix things

So, after hitting Alt+D, the “File Name to write” line changes, see below:

Yey, no pesky “DOS Format” warning here!

Using either editor (or any others, if you know how to solve line ending issues in other editors), you still need to combine your script back together before you can run it, so… do that, and your file will be fine to run! Good luck!

Featured image is β€œFishing line and bobbin stuck on tree at Douthat State Park” by β€œVirginia State Parks” on Flickr and is released under a CC-BY license.

"Root" by "llee_wu" on Flickr

A quick note on using Firefox in Windows in a Corporate or Enterprise environment

I’ve been using Firefox as my “browser of choice” for around 15 years. I tend to prefer to use it for all sorts of reasons, but the main thing I expect is support for extensions. Not many of them, but … well, there’s a few!

There are two stumbling blocks for using Firefox in a corporate or enterprise setting. These are:

  1. NTLM or Kerberos Authentication for resources like Sharepoint and ADFS.
  2. Enterprise TLS certificates (usually deployed via GPO as part of the domain)

These are both trivially fixed in the about:config screen, but first you need to get past a scary looking warning page!

In the address bar, where it probably currently says jon.sprig.gs, click in there and type about:config.

Getting to about:config

This brings you to a scary page!

Proceed with caution! (of course!!)

Click the “Accept the Risk and Continue” (note, this is with Firefox 76. Wording with later or earlier versions may differ).

As if it wasn’t obvious enough from the previous screen, this “may impact performance and security”…

And then you get a search box.

In the “Search preference name” type in ntlm and find the line that says network.automatic-ntlm-auth.trusted-uris.

The “NTLM Options page”

Type in there the suffixes of any TRUSTED domains. For example, if your company uses the domain names of bigcompany.com, bigco.local and big.company then you’d type in:

bigcompany.com,bigco.local,big.company

Any pages that you browse to, where they request NTLM authentication, will receive an NTLM set of credentials if prompted (same as IE, Edge, and Chrome already do!) NTLM is effectively a way to pass a trusted Kerberos ticket (a bit like your domain credentials) into a web page.

Next up, let’s get those pesky certificate errors removed!

This assumes that you have a centrally managed TLS Root Certificate, and the admins in your network haven’t just been dumping self signed certificates everywhere (nothing gets around that… just sayin’).

Still in about:config, clear the search box and type enterprise, like this!

Enterprise Roots are here!

Find the line security.enterprise_roots.enabled and make sure it says true. If it doesn’t double click it, so it does.

Now you can close your preferences page, and you should be fine to visit your internal source code repository, time sheeting system or sharepoint site, with almost no interruptions!

If you’ve been tasked for turning this stuff on in your estate of managed desktop environment machines, then you might find this article (on Autoconfiguration of Firefox) of use (but I’ve not tried it!)

Featured image is “Root” by “llee_wu” on Flickr and is released under a CC-BY-ND license.

Publishing a “Bio” in Secure Scuttlebutt, using ssb-server

This is one of those “oh, there it is” posts, more for myself than anyone else. Anyway, if you use SSB from a shell (perhaps you run your own SSB Pub, for example), you might want to run this style of command:

ssb-server publish --type about --about "$(ssb-server whoami | jq .id -r)" --name "Some Server" --description "I'm just some server, you know"

As long as you have --name or --description in there, you should be good to go!

"vieux port Marseille" by "Jeanne Menjoulet" on Flickr

Networking tricks with Multipass in Virtualbox on Windows (Bridged interfaces and Port Forwards)

TL;DR? Want to “just” bridge one or more interfaces to a Multipass instance when you’re using Virtualbox? See the Bridging Summary below. Want to do a port forward? See the Port Forward section below. You will need the psexec command and to execute this as an administrator. The use of these two may be considered a security incident on your computing environment, depending on how your security processes and infrastructure are defined and configured.

Ah Multipass. This is a tool created by Canonical to create a “A mini-cloud on your Mac or Windows workstation.” (from their website)…

I’ve often seen this endorsed as the tool of choice from Canonical employees to do “stuff” like run Kubernetes, develop tools for UBPorts (previously Ubuntu Touch) devices, and so on.

So far, it seems interesting. It’s a little bit like Vagrant with an in-built cloud-init Provisioner, and as I want to test out the cloud-init files I’m creating for AWS and Azure, that’d be so much easier than actually building the AWS or Azure machines, or finding a viable cloud-init plugin for Vagrant to test it out.

BUT… Multipass is really designed for Linux systems (running LibVirt), OS X (running HyperKit) and Windows (running Hyper-V). Even if I were using Windows 10 Pro on this machine, I use Virtualbox for “things” on my Windows Machine, and Hyper-V steals the VT-X bit, which means that VirtualBox can’t run x64 code…. Soooo I can’t use the Hyper-V mode.

Now, there is a “fix” for this. You can put Multipass into Virtualbox mode, which lets you run Multipass on Windows or OS X without using their designed-for hypervisor, but this has a downside, you see, VirtualBox doesn’t give MultiPass the same interface to route networking connections to the VM, and there’s currently no CLI or GUI options to say “bridge my network” or “forward a port” (in part because it needs to be portable to the native hypervisor options, apparently). So, I needed to fudge some things so I can get my beloved bridged connections.

I got to the point where I could do this, thanks to the responses to a few issues I raised on the Multipass Github issues, mostly #1333.

The first thing you need to install in Windows is PsExec, because Multipass runs it’s Virtual Machines as the SYSTEM account, and talking to SYSTEM account processes is nominally hard. Get PsExec from the SysInternals website. Some IT Security professionals will note the addition of PsExec as a potential security incident, but then again, they might also see the running of a virtual machine as a security incident too, as these aren’t controlled with a central image. Anyway… Just bear it in mind, and don’t shout at me if you get frogmarched in front of your CISO.

I’m guessing if you’re here, you’ve already installed Multipass, (but if not, and it seems interesting – it’s over at https://multipass.run. Get it and install it, then carry on…) and you’ve probably enabled the VirtualBox mode (if not – open a command prompt as administrator, and run “multipass set local.driver=virtualbox“). Now, you can start sorting out your bridges.

Sorting out bridges

First things first, you need to launch a virtual machine. I did, and it generated a name for my image.

C:\Users\JON>multipass launch
Launched: witty-kelpie

Fab! We have a running virtual machine, and you should be able to get a shell in there by running multipass shell "witty-kelpie" (the name of the machine it launched before). But, uh-oh. We have the “default” NAT interface of this device mapped, not a bridged interface.

C:\Users\JON>multipass shell "witty-kelpie"
Welcome to Ubuntu 18.04.3 LTS (GNU/Linux 4.15.0-76-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

  System information as of Thu Feb  6 10:56:38 GMT 2020

  System load:  0.3               Processes:             82
  Usage of /:   20.9% of 4.67GB   Users logged in:       0
  Memory usage: 11%               IP address for enp0s3: 10.0.2.15
  Swap usage:   0%


0 packages can be updated.
0 updates are security updates.


To run a command as administrator (user "root"), use "sudo <command>".
See "man sudo_root" for details.

ubuntu@witty-kelpie:~$

So, exit the machine, and issue a multipass stop "witty-kelpie" command to ask Virtualbox to shut it down.

So, this is where the fun[1] part begins.
[1] The “Fun” part here depends on how you view this specific set of circumstances πŸ˜‰

We need to get the descriptions of all the interfaces we might want to bridge to this device. I have three interfaces on my machine – a WiFi interface, a Ethernet interface on my laptop, and an Ethernet interface on my USB3 dock. At some point in the past, I renamed these interfaces, so I’d recognise them in the list of interfaces, so they’re not just called “Connection #1”, “Connection #2” and so on… but you should recognise your interfaces.

To get this list of interfaces, open PowerShell (as a “user”), and run this command:

PS C:\Users\JON> Get-NetAdapter -Physical | format-list -property "Name","DriverDescription"

Name              : On-Board Network Connection
DriverDescription : Intel(R) Ethernet Connection I219-LM

Name              : Wi-Fi
DriverDescription : Intel(R) Dual Band Wireless-AC 8260

Name              : Dock Network Connection
DriverDescription : DisplayLink Network Adapter NCM

For reasons best known to the Oracle team, they use the “Driver Description” to identify the interfaces, not the name assigned to the device by the user, so, before we get started, find your interface, and note down the description for later. If you want to bridge “all” of them, make a note of all the interfaces in question, and in the order you want to attach them. Note that Virtualbox doesn’t really like exposing more than 8 NICs without changing the Chipset to ICH9 (but really… 9+ NICs? really??) and the first one is already consumed with the NAT interface you’re using to connect to it… so that gives you 7 bridgeable interfaces. Whee!

So, now you know what interfaces you want to bridge, let’s configure the Virtualbox side. Like I said before you need psexec. I’ve got psexec stored in my Downloads folder. You can only run psexec as administrator, so open up an Administrator command prompt or powershell session, and run your command.

Just for clarity, your commands are likely to have some different paths, so remember that wherever “your” PsExec64.exe command is located, mine is in C:\Users\JON\Downloads\sysinternals\PsExec64.exe, and wherever your vboxmanage.exe is located, mine is in C:\Program Files\Oracle\VirtualBox\vboxmanage.exe.

Here, I’m going to attach my dock port (“DisplayLink Network Adapter NCM”) to the second VirtualBox interface, the Wifi adaptor to the third interface and my locally connected interface to the fourth interface. Your interfaces WILL have different descriptions, and you’re likely not to need quite so many of them!

C:\WINDOWS\system32>C:\Users\JON\Downloads\sysinternals\PsExec64.exe -s "c:\program files\oracle\virtualbox\vboxmanage" modifyvm "witty-kelpie" --nic2 bridged --bridgeadapter2 "DisplayLink Network Adapter NCM" --nic3 bridged --bridgeadapter3 "Intel(R) Dual Band Wireless-AC 8260" --nic4 bridged --bridgeadapter4 "Intel(R) Ethernet Connection I219-LM"

PsExec v2.2 - Execute processes remotely
Copyright (C) 2001-2016 Mark Russinovich
Sysinternals - www.sysinternals.com

c:\program files\oracle\virtualbox\vboxmanage exited on MINILITH with error code 0.

An error code of 0 means that it completed successfuly and with no issues.

If you wanted to use a “Host Only” network (if you’re used to using Vagrant, you might know it as “Private” Networking), then change the NIC you’re interested in from --nicX bridged --bridgeadapterX "Some Description" to --nicX hostonly --hostonlyadapterX "VirtualBox Host-Only Ethernet Adapter" (where X is replaced with the NIC number you want to swap, ranged between 2 and 8, as 1 is the NAT interface you use to SSH into the virtual machine.)

Now we need to check to make sure the machine has it’s requisite number of interfaces. We use the showvminfo flag to the vboxmanage command. It produces a LOT of content, so I’ve manually filtered the lines I want, but you should spot it reasonably quickly.

C:\WINDOWS\system32>C:\Users\JON\Downloads\sysinternals\PsExec64.exe -s "c:\program files\oracle\virtualbox\vboxmanage" showvminfo "witty-kelpie"

PsExec v2.2 - Execute processes remotely
Copyright (C) 2001-2016 Mark Russinovich
Sysinternals - www.sysinternals.com


Name:                        witty-kelpie
Groups:                      /Multipass
Guest OS:                    Ubuntu (64-bit)
<SNIP SOME CONTENT>
NIC 1:                       MAC: 0800273CCED0, Attachment: NAT, Cable connected: on, Trace: off (file: none), Type: 82540EM, Reported speed: 0 Mbps, Boot priority: 0, Promisc Policy: deny, Bandwidth group: none
NIC 1 Settings:  MTU: 0, Socket (send: 64, receive: 64), TCP Window (send:64, receive: 64)
NIC 1 Rule(0):   name = ssh, protocol = tcp, host ip = , host port = 53507, guest ip = , guest port = 22
NIC 2:                       MAC: 080027303758, Attachment: Bridged Interface 'DisplayLink Network Adapter NCM', Cable connected: on, Trace: off (file: none), Type: 82540EM, Reported speed: 0 Mbps, Boot priority: 0, Promisc Policy: deny, Bandwidth group: none
NIC 3:                       MAC: 0800276EA174, Attachment: Bridged Interface 'Intel(R) Dual Band Wireless-AC 8260', Cable connected: on, Trace: off (file: none), Type: 82540EM, Reported speed: 0 Mbps, Boot priority: 0, Promisc Policy: deny, Bandwidth group: none
NIC 4:                       MAC: 080027042135, Attachment: Bridged Interface 'Intel(R) Ethernet Connection I219-LM', Cable connected: on, Trace: off (file: none), Type: 82540EM, Reported speed: 0 Mbps, Boot priority: 0, Promisc Policy: deny, Bandwidth group: none
NIC 5:                       disabled
NIC 6:                       disabled
NIC 7:                       disabled
NIC 8:                       disabled
<SNIP SOME CONTENT>

Configured memory balloon size: 0MB

c:\program files\oracle\virtualbox\vboxmanage exited on MINILITH with error code 0.

Fab! We now have working interfaces… But wait, let’s start that VM back up and see what happens.

C:\Users\JON>multipass shell "witty-kelpie"
Welcome to Ubuntu 18.04.3 LTS (GNU/Linux 4.15.0-76-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

  System information as of Thu Feb  6 11:31:08 GMT 2020

  System load:  0.1               Processes:             84
  Usage of /:   21.1% of 4.67GB   Users logged in:       0
  Memory usage: 11%               IP address for enp0s3: 10.0.2.15
  Swap usage:   0%


0 packages can be updated.
0 updates are security updates.


Last login: Thu Feb  6 10:56:45 2020 from 10.0.2.2
To run a command as administrator (user "root"), use "sudo <command>".
See "man sudo_root" for details.

ubuntu@witty-kelpie:~$

Wait, what….. We’ve still only got the one interface up with an IP address… OK, let’s fix this!

As of Ubuntu 18.04, interfaces are managed using Netplan, and, well, when the VM was built, it didn’t know about any interface past the first one, so we need to get Netplan to get them enabled. Let’s check they’re detected by the VM, and see what they’re all called:

ubuntu@witty-kelpie:~$ ip link
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
    link/ether 08:00:27:3c:ce:d0 brd ff:ff:ff:ff:ff:ff
3: enp0s8: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 08:00:27:30:37:58 brd ff:ff:ff:ff:ff:ff
4: enp0s9: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 08:00:27:6e:a1:74 brd ff:ff:ff:ff:ff:ff
5: enp0s10: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 08:00:27:04:21:35 brd ff:ff:ff:ff:ff:ff
ubuntu@witty-kelpie:~$ 

If you compare the link/ether lines to the output from showvminfo we executed before, you’ll see that the MAC address against enp0s3 matches the NAT interface, while enp0s8 matches the DisplayLink adapter, and so on… So we basically want to ask NetPlan to do a DHCP lookup for all the new interfaces we’ve added to it. If you’ve got 1 NAT and 7 physical interfaces (why oh why…) then you’d have enp0s8, 9, 10, 16, 17, 18 and 19 (I’ll come back to the random numbering in a tic)… so we now need to ask Netplan to do DHCP on all of those interfaces (assuming we’ll be asking for them all to come up!)

If we want to push that in, then we need to add a new file in /etc/netplan called something like 60-extra-interfaces.yaml, that should contain:

network:
  ethernets:
    enp0s8:
      optional: yes
      dhcp4: yes
      dhcp4-overrides:
        route-metric: 10
    enp0s9:
      optional: yes
      dhcp4: yes
      dhcp4-overrides:
        route-metric: 11
    enp0s10:
      optional: yes
      dhcp4: yes
      dhcp4-overrides:
        route-metric: 12
    enp0s16:
      optional: yes
      dhcp4: yes
      dhcp4-overrides:
        route-metric: 13
    enp0s17:
      optional: yes
      dhcp4: yes
      dhcp4-overrides:
        route-metric: 14
    enp0s18:
      optional: yes
      dhcp4: yes
      dhcp4-overrides:
        route-metric: 15
    enp0s19:
      optional: yes
      dhcp4: yes
      dhcp4-overrides:
        route-metric: 16

Going through this, we basically ask netplan not to assume the interfaces are attached. This stops the boot process for waiting for a timeout to configure each of the interfaces before proceeding, so it means your boot should be reasonably fast, particularly if you don’t always attach a network cable or join a Wifi network on all your interfaces!

We also say to assume we want IPv4 DHCP on each of those interfaces. I’ve done IPv4 only, as most people don’t use IPv6 at home, but if you are doing IPv6 as well, then you’d also need the same lines that start dhcp4 copied to show dhcp6 (like dhcp6: yes and dhcp6-overrides: route-metric: 10)

The eagle eyed of you might notice that the route metric increases for each extra interface. This is because realistically, if you have two interfaces connected (perhaps if you’ve got wifi enabled, and plug a network cable in), then you’re more likely to want to prioritize traffic going over the lower numbered interfaces than the higher number interfaces.

Once you’ve created this file, you need to run netplan apply or reboot your machine.

So, yehr, that gets you sorted on the interface front.

Bridging Summary

To review, you launch your machine with multipass launch, and immediately stop it with multipass stop "vm-name", then, as an admin, run psexec vboxmanage modifyvm "vm-name" --nic2 bridged --bridgedadapter2 "NIC description", and then start the machine with multipass start "vm-name". Lastly, ask the interface to do DHCP by manipulating your Netplan configuration.

Interface Names in VirtualBox

Just a quick note on the fact that the interface names aren’t called things like eth0 any more. A few years back, Ubuntu (amongst pretty much all of the Linux distribution vendors) changed from using eth0 style naming to what they call “Predictable Network Interface Names”. This derives the names from things like, what the BIOS provides for on-board interfaces, slot index numbers for PCI Express ports, and for this case, the “geographic location of the connector”. In Virtualbox, these interfaces are provided as the “Geographically” attached to “port 0” (so enp0 are all on port 0), but for some reason, they broadcast themselves as being attached to the port 0 at “slots” 3, 8, 9, 10, 16, 17, 18 and 19… hence enp0s3 and so on. shrug It just means that if you don’t have the interfaces coming up on the interfaces you’re expecting, you need to run ip link to confirm the MAC addresses match.

Port Forwarding

Unlike with the Bridging, we don’t need to power down the VM to add the extra interfaces, we just need to use psexec (as an admin again) to execute a vboxmanage command – in this case, it’s:

C:\WINDOWS\system32>C:\Users\JON\Downloads\sysinternals\PsExec64.exe -s "c:\program files\oracle\virtualbox\vboxmanage" controlvm "witty-kelpie" --natpf1 "myport,tcp,,1234,,2345"

OK, that’s a bit more obscure. Basically it says “Create a NAT rule on NIC 1 called ‘myport’ to forward TCP connections from port 1234 attached to any IP associated to the host OS to port 2345 attached to the DHCP supplied IP on the guest OS”.

If we wanted to run a DNS server in our VM, we could run multiple NAT rules in the same command, like this:

C:\WINDOWS\system32>C:\Users\JON\Downloads\sysinternals\PsExec64.exe -s "c:\program files\oracle\virtualbox\vboxmanage" controlvm "witty-kelpie" --natpf1 "TCP DNS,tcp,127.0.0.1,53,,53" --natpf1 "UDP DNS,udp,127.0.0.1,53,,53"

If we then decide we don’t need those NAT rules any more, we just (with psexec and appropriate paths) issue: vboxmanage controlvm "vm-name" --natpf1 delete "TCP DNS"

Using ifupdown instead of netplan

Late Edit 2020-04-01: On Github, someone asked me how they could use the same type of config with netplan, but instead on a 16.04 system. Ubuntu 16.04 doesn’t use netplan, but instead uses ifupdown instead. Here’s how to configure the file for ifupdown:

You can either add the following stanzas to /etc/network/interfaces, or create a separate file for each interface in /etc/network/interfaces.d/<number>-<interface>.cfg (e.g. /etc/network/interfaces.d/10-enp0s8.cfg)

allow-hotplug enp0s8
iface enp0s8 inet dhcp
  metric 10

To re-iterate, in the above netplan file, the interfaces we identified were: enp0s8, enp0s9, enp0s10, enp0s16, enp0s17, enp0s18 and enp0s19. Each interface was incrementally assigned a route metric, starting at 10 and ending at 16, so enp0s8 has a metric of 10, while enp0s16 has a metric of 13, and so on. To build these files, I’ve created this brief shell script you could use:

export metric=10
for int in 8 9 10 16 17 18 19
do
  echo -e "allow-hotplug enp0s${int}\niface enp0s${int} inet dhcp\n  metric $metric" > /etc/network/interfaces.d/enp0s${int}.cfg
  ((metric++))
done

As before, you could reboot to make the changes to the interfaces. Bear in mind, however, that unlike Netplan, these interfaces will try and DHCP on boot with this configuration, so boot time will take longer if every interface attached isn’t connected to a network.

Using NAT Network instead of NAT Interface

Late update 2020-05-26: Ruzsinsky contacted me by email to ask how I’d use a “NAT Network” instead of a “NAT interface”. Essentially, it’s the same as the Bridged interface above, with one other tweak first, we need to create the Net Network, with this command (as an Admin)

C:\WINDOWS\system32>C:\Users\JON\Downloads\sysinternals\PsExec64.exe -s "c:\program files\oracle\virtualbox\vboxmanage" natnetwork add --netname MyNet --network 192.0.2.0/24

Next, stop your multipass virtual machine with multipass stop "witty-kelpie", and configure your second interface, like this:

C:\WINDOWS\system32>C:\Users\JON\Downloads\sysinternals\PsExec64.exe -s "c:\program files\oracle\virtualbox\vboxmanage" modifyvm "witty-kelpie" --nic2 natnetwork --nat-network2 "MyNet"

PsExec v2.2 - Execute processes remotely
Copyright (C) 2001-2016 Mark Russinovich
Sysinternals - www.sysinternals.com

c:\program files\oracle\virtualbox\vboxmanage exited on MINILITH with error code 0.

Start the vm with multipass start "witty-kelpie", open a shell with it multipass shell "witty-kelpie", become root sudo -i and then configure the interface in /etc/netplan/60-extra-interfaces.yaml like we did before:

network:
  ethernets:
    enp0s8:
      optional: yes
      dhcp4: yes
      dhcp4-overrides:
        route-metric: 10

And then run netplan apply or reboot.

What I would say, however, is that the first interface seems to be expected to be a NAT interface, at which point, having a NAT network as well seems a bit pointless. You might be better off using a “Host Only” (or “Private”) network for any inter-host communications between nodes at a network level… But you know your environments and requirements better than I do :)

Featured image is “vieux port Marseille” by “Jeanne Menjoulet” on Flickr and is released under a CC-BY-ND license.