Generic OAuth2: decoding the user json

[ccoenen]

I would love to complete my nextcloud login I mentioned in #189, but it turns out that I was missing one part: I am not receiving the X-Forwarded-User header. I believe, traefik-forward-auth currently has no way of configuring where to look for that info, right? I may be missing something, but I did not find a config option for that.

Nextcloud returns this info at the USER_URL (example taken from nextcloud/server#5694 (comment) !)

{
   "ocs":{
      "meta":{
         "status":"ok",
         "statuscode":200,
         "message":"OK"
      },
      "data":{
         "enabled":"true",
         "id":"lukas",
         "quota":{
            "free":3909529214976,
            "used":6657835832,
            "total":3916187050808,
            "relative":0.17,
            "quota":-3
         },
         "email":"lukas@nextcloud.com",
         "phone":"",
         "address":"",
         "website":"",
         "twitter":"",
         "groups":[
            "Engineering",
            "General"
         ],
         "display-name":"Lukas Reschke"
      }
   }
}

So, in other oauth adapters, I configure these things:

username: "ocs.data.id"
displayname: "ocs.data.display-name",
email: "ocs.data.email"
groups: "ocs.data.groups"

and so on.

If I'm reading this correctly, there's no such option (yet) in traefik-forward-auth, it is always parsed into the same User object:

traefik-forward-auth/internal/provider/generic_oauth.go

Line 93 in 04f5499

err = json.NewDecoder(res.Body).Decode(&user)

that object is defined here, but I do not think I can configure it in any way?

traefik-forward-auth/internal/provider/providers.go

Lines 31 to 33 in 04f5499

	type User struct {
	Email string `json:"email"`
	}

I would like to request this as a configurable option, or if it is already, a pointer on how to configure this.

[thomseddon]

We actually have a PR proposed for this currently in #159

I still need to do a little more review on that before it's merged, but I'm guessing that will work for you?