Feature request: add auth config snippet with new annotation nginx.ingress.kubernetes.io/auth-snippet

[benjamingorman]

Is this a BUG REPORT or FEATURE REQUEST? (choose one): FEATURE REQUEST

This is a request to add a new annotation nginx.ingress.kubernetes.io/auth-snippet. The annotation would function in the same way as the existing snippet annotations:

• nginx.ingress.kubernetes.io/server-snippet and
• nginx.ingress.kubernetes.io/configuration-snippet.

The auth snippet would be inserted into the auth request block in nginx.conf.

It could be used alongside auth-url for example:

annotations:
  nginx.ingress.kubernetes.io/auth-url: http://my-auth-service:8080
  nginx.ingress.kubernetes.io/auth-snippet: |
     proxy-set-header My-Custom-Header 42;

The reason I think this feature would be useful is because I had a use case where I had to add an extra header to the auth subrequest. It seemed like the only way to do this was using a custom template, and modifying the auth request block in the custom template. This feature would remove the need to do that (although please let me know if it's possible already and I've somehow missed that).

Please let me know if this seems sensible - I'm happy to work on a MR if that helps too.

[benjamingorman]

Thanks for adding this! That's great.