Troubleshooting FortiGate API issues with the CLI?

One of my colleagues has asked me for some help with an Ansible script he’s writing to push some policy to a cloud hosted FortiGate appliance. Unfortunately, he kept getting some very weird error messages, like this one:

fatal: [localhost]: FAILED! => {"changed": false, "meta": {"build": 200, "error": -651, "http_method": "PUT", "http_status": 500, "mkey": "vip8080", "name": "vip", "path": "firewall", "revision": "36.0.0.10745196634707694665.1544442857", "serial": "CENSORED", "status": "error", "vdom": "root", "version": "v6.0.3"}, "msg": "Error in repo"}

This is using Fortinet’s own Ansible Modules, which, in turn use the fortiosapi python module.

This same colleague came across a post on the Fortinet Developer Network site (access to the site requires vendor approval), which said “this might be an internal bug, but to debug it, use the following”

fgt # diagnose debug enable

fgt # diagnose debug cli 8
Debug messages will be on for 30 minutes.

And then run your API commands. Your error message will be surfaced there… so here’s mine! (Mapped port doesn’t match extport in a vip).

0: config firewall vip
0: edit "vip8080"
0: unset src-filter
0: unset service
0: set extintf "port1"
0: set portforward enable
0: unset srcintf-filter
0: set mappedip "192.0.2.1-192.0.2.1"
0: unset extport
0: set extport 8080-8081
0: unset mappedport
0: set mappedport 8080
-651: end

Late edit 2020-03-27: I spotted a bug in the Ansible issues tracker today, and I added a note to the end of that bug mentioning that as well as diagnose debug cli 8, if that doesn’t give you enough logs to figure out what’s up, you can also try diagnose debug application httpsd -1 but this enables LOTS AND LOTS of logs, so really think twice before turning that one on!

Oh, and if 30 minutes isn’t enough, try diagnose debug duration 480 or however many minutes you think you need. Beware that it will write event logs out to the serial console even when you’ve logged out.