Add api support for external authentication management

[uvulpos]

Summary:

As a DevOps Engineer, I want an automatic infrastructure setup with terraform and therefor have to enhance the gitea external api.

API:

+ GET - /api/v1/admin/identity-auth/oauth/
+ PUT - /api/v1/admin/identity-auth/oauth/
+ PATCH - /api/v1/admin/identity-auth/oauth/{id}
+ DELETE - /api/v1/admin/identity-auth/oauth/{id}

Terraform (later):

resource "gitea_login_source_provider" "oauth_authentik" {
  Name: "Authentik"
  Icon: "..."

  ConfigUrl = "..."
  ClientID = "..."
  ClientSecret = "..."
}

Todos:

• Implement api endpoints
  • Get - Return Login Sources<
  • Put - Create an Oauth2 Source
  • Patch - Update an Oauth2 Source
  • Delete - Remove Oauth2 Source
  • Document API Endpoints inside Swagger
  • PR Feedback
    • Get Configuration by ID
    • Filter OAuth Configurations for type Oauth
    • Implement General Get Auth List for all kind of authentications
    • copyright date in new files should be from this year and I don't think gogs attribution here is needed(?)
    • comments in services/convert/auth_oauth.go don't match the functions
    • Remove Type ID from OAuth Return Struct

Other:

• Existing CLI Implementation of that feature

This is my first contribution to gitea so any help is appreciated

[uvulpos]

parameter via url or url param?

[TheFox0x7]

Unless someone else has different opinion I think it should stay like this.
What about getting the current configuration for an ID?

[uvulpos]

But what's the current configuration? We can have n login sources configured and you can access it via pat so no auth source is getting used at all

Ok, I'll add this feature to get a config by ID

[uvulpos]

Filter and return just type OAuth
[Help appreciated]

[TheFox0x7]

I'm not sure search is needed? Second opinion would be nice this though.

[uvulpos]

The url explicit says oauth, so I'm not sure if I want to receive LDAP connections

[TheFox0x7]

To filter for oauth only you should add LoginType: auth_model.OAuth2 to the struct.

But I was wondering why oauth search specifically instead of more generic one? The struct doesn't really let you filter by much more too.

[TheFox0x7]

I haven't tested the changes yet or looked too deep into it, at a glance it looks like it's a good starting point.
In case you haven't yet seen it: https://github.com/go-gitea/gitea/blob/main/cmd/admin_auth_oauth.go covers cli endpoint for adding oauth, which you might find useful.

Few minor points:

• copyright date in new files should be from this year and I don't think gogs attribution here is needed(?)
• comments in services/convert/auth_oauth.go don't match the functions

[TheFox0x7]

I'm not sure why end user would be interested in numeric type?

[uvulpos]

I was not sure, but I think it's more unique than the name for machine readability. But... I don't know. Opinions are welcome :)

[TheFox0x7]

Unless someone else has different opinion I think it should stay like this.
What about getting the current configuration for an ID?

[TheFox0x7]

I'm not sure search is needed? Second opinion would be nice this though.