Add keycloak provider

[Ofinka]

Adding integration of keycloak provider based on forgotten PR https://github.com/bitly/oauth2_proxy/pull/366/files

Solves #127

How Has This Been Tested?

Tested manually. I set up keycloak and reference it in configuration of oauth2_proxy using this provider.

• My change requires a change to the documentation or CHANGELOG.
• I have updated the documentation/CHANGELOG accordingly.
• I have created a feature (non-master) branch for my PR.

[mannp]

Excellent, thank you for taking the time to do this :-)

[loshz]

LGTM 👍 - @JoelSpeed do we have any additional processes that need completing when adding a new provider?

[JoelSpeed]

I've typically asked people to become maintainers of the provider and add themselves for the new files to the owners file, though I'm happy to let this one slide as it's pretty simple (and is mainly just the group email fetching code)

Need one small change then we can merge this

[loshz]

LGTM 👍

[steakunderscore]

@Ofinka Do you mind adding yourself to the owners file for future changes? https://github.com/pusher/oauth2_proxy/blob/master/.github/CODEOWNERS#L12

[mannp]

Has this one stalled now, as it seemed to be close to getting merged 😃

[Ofinka]

Hi guys, I'm sorry but I'm afraid I do not have enough time to be part of another project :(

Would definitely appreciate if anyone else could take the responsibility.

[steakunderscore]

Understood. I think we should merge this as is.

[JoelSpeed]

Hi guys, I'm sorry but I'm afraid I do not have enough time to be part of another project :(

I appreciate this...

If you can fix up the extra lines added to the changelog then I'm happy to merge as is, thanks! 🙂

[mleklund]

Would love to see this move along.

[loshz]

If we can fix @JoelSpeed's comment above, then I can get this merged.

[mleklund]

The author of the pull request has not responded since August 19, not sure when or if they will.

[loshz]

I have fixed the CHANGELOG error. Just need to get it re-reviewed by @JoelSpeed or @steakunderscore

[JoelSpeed]

Ok, LGTM

[loshz]

Thank you and congrats on your first contribution! 🎉

[mleklund]

Thanks for your help!!