Request for better feedback around --configmap= option

[toothbrush]

Hi! Thanks for maintaining haproxy-ingress! 👍 I ran into a small annoyance while setting up a new instance, so i thought i'd share.

Description of the problem

Setting up a new instance of haproxy-ingress, things didn't work as expected; it turned out it wasn't reading my configmap. It was difficult to track down the problem – it turned out i was setting --configmap=wrongnamespace/nonexistent-myconfigmap but haproxy-ingress accepted it silently.

Additionally, the --configmap=... option isn't mentioned on https://haproxy-ingress.github.io/docs/configuration/command-line/, adding to my confusion. It is mentioned here though:

https://github.com/jcmoraisjr/haproxy-ingress/blob/42034000bc7e4516696fc7f107b6a2d9b82588a3/examples/custom-configuration/README.md#L29-31

Expected behavior

At least i would expect a log line output, or better yet a fatal crash if the user passes --configmap=... pointing at a ConfigMap that cannot be read. This would've pointed me straight to the issue.

Additionally, it could be nice to output to the console something like "Successfully loaded configuration from ConfigMap your/configmap." so that you know that's working.

Steps to reproduce the problem

1. Call haproxy-ingress with --configmap=nonexistent.

Environment information

HAProxy Ingress version: v0.12.3

[jcmoraisjr]

Hi thanks for reporting this. We really need to spend a few more time with the command-line options doc.

Regarding the configmap reading, this is in fact a historical and annoying misbehavior. I'll add an error log in the maintenance branches so we don't break deployments that uses this as a feature, and will crash the application on new versions.

[jcmoraisjr]

v0.10.9, v0.11.8 and v0.12.6 will now log if the global --configmap cannot be found, and v0.13.0-beta.2 and newer will crash. Closing.