Add Gitlab OAuth

[paddatrapper]

Adds GitLab support to the OAuth authentication structure.

It is discussed here. Currently clicking on the 'Login with GitLab' button results in a 404 error.

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• I have signed the CLA

[paddatrapper]

I have fixed the issues and can now successfully log in using GitLab OAuth as the authentication method

[thebaer]

Some things I'm wondering about:

• Should we simplify configuration so you only need to set the Gitlab instance hostname? Then the application could just append the path to the URL for each endpoint.
• Should we make the "Sign in with Gitlab" button text configurable? I'm thinking users might want to know which Gitlab instance they'd be authenticating with.

Thoughts?

[paddatrapper]

Should we simplify configuration so you only need to set the Gitlab instance hostname? Then the application could just append the path to the URL for each endpoint.

I would prefer this, but I wasn't sure if the API server could be a separate URL to the instance. Does anyone know if that is possible?

Should we make the "Sign in with Gitlab" button text configurable? I'm thinking users might want to know which Gitlab instance they'd be authenticating with.

Good idea. Will do

[thebaer]

I would prefer this, but I wasn't sure if the API server could be a separate URL to the instance. Does anyone know if that is possible?

I'm not sure. But if we don't hear otherwise, I think we can go ahead and implement it that way now. If we pick a good name for the config field, we can always re-add the fields for specific endpoints in the future, if they turn out to be necessary.

Good idea. Will do

Awesome, sounds good. Of course, it'd probably be good to fall back to some kind of default string if there's none configured.

[ngerakines]

There isn't any reason it can't be separate. The only consideration is making sure that we're not hardcoding any gitlab.com URLs so people with private/self-hosted instances can use it.

[paddatrapper]

I'm not sure. But if we don't hear otherwise, I think we can go ahead and implement it that way now. If we pick a good name for the config field, we can always re-add the fields for specific endpoints in the future, if they turn out to be necessary.

Done

Awesome, sounds good. Of course, it'd probably be good to fall back to some kind of default string if there's none configured.

Defaults to GitLab if not configured

[thebaer]

Just a few comments on the field names to keep things tidy. Otherwise this looks good to me!

[paddatrapper]

Fixed

[thebaer]

Thanks @paddatrapper and @ngerakines! Merging now.