Discourse OAuth2 Basic Support

:discourse2: Summary Discourse OAuth2 Basic supports basic OAuth2 providers, assuming they have a JSON API endpoint where user details can be retrieved by token.
:hammer_and_wrench: Repository Link https://github.com/discourse/discourse-oauth2-basic
:open_book: Install Guide How to install plugins in Discourse

Features

This plugin allows you to use a basic OAuth2 provider as authentication for Discourse. It should work with many providers, with the caveat that they must provide a JSON endpoint for retrieving information about the user you are logging in.

This is mainly useful for people who are using login providers that aren’t very popular. If you want to use Google, Facebook or Twitter, those are included out of the box and you don’t need this plugin. You can also look for other login providers in our Github Repo.

Configuration

1: Basic Configuration

First, set up your Discourse application remotely on your OAuth2 provider. It will require a Redirect URI which should be:

http://DISCOURSE_HOST/auth/oauth2_basic/callback

Replace DISCOURSE_HOST with the approriate value, and make sure you are using https if enabled. The OAuth2 provider should supply you with a client ID and secret, as well as a couple of URLs.

Visit your AdminSettingsLogin and fill in the basic configuration for the OAuth2 provider:

  • oauth2_enabled - check this off to enable the feature
  • oauth2_client_id - the client ID from your provider
  • oauth2_client_secret - the client secret from your provider
  • oauth2_authorize_url - your provider’s authorization URL
  • oauth2_token_url - your provider’s token URL.

If you can’t figure out the values for the above settings, check the developer documentation from your provider or contact their customer support.

2: Configuring the JSON User Endpoint

Discourse is now capable of receiving an authorization token from your OAuth2 provider. Unfortunately, Discourse requires more information to be able to complete the authentication.

We require an API endpoint that can be contacted to retrieve information about the user based on the token.

For example, the OAuth2 provider SoundCloud provides such a URL. If you have an OAuth2 token for SoundCloud, you can make a GET request to https://api.soundcloud.com/me?oauth_token=A_VALID_TOKEN and will get back a JSON object containing information on the user.

To configure this on Discourse, we need to set the value of the oauth2_user_json_url setting. In this case, we’ll input the value of:

https://api.soundcloud.com/me?oauth_token=:token

The part with :token tells Discourse that it needs to replace that value
with the authorization token it received when the authentication completed.

There is one last step to complete. We need to tell Discourse what
attributes are available in the JSON it received. Here’s a sample
response from SoundCloud:

{
  "id": 3207,
  "permalink": "jwagener",
  "username": "Johannes Wagener",
  "uri": "https://api.soundcloud.com/users/3207",
  "permalink_url": "http://soundcloud.com/jwagener",
  "avatar_url": "http://i1.sndcdn.com/avatars-000001552142-pbw8yd-large.jpg?142a848",
  "country": "Germany",
  "full_name": "Johannes Wagener",
  "city": "Berlin"
}

The oauth2_json_user_id_path, oauth2_json_username_path, oauth2_json_name_path and oauth2_json_email_path variables should be set to point to the appropriate attributes in the JSON.

The only mandatory attribute is id - we need that so when the user logs on in the future that we can pull up the correct account. The others are great if available – they will make the signup process faster for the user as they will be pre-populated in the form.

Here’s how I configured the JSON path settings:

  oauth2_json_user_id_path: 'id'
  oauth2_json_username_path: 'permalink'
  oauth2_json_name_path: 'full_name'

I used permalink because it seems more similar to what Discourse expects for a username than the username in their JSON. Notice I omitted the email path: SoundCloud do not provide an email so the user will have to provide and verify this when they sign up the first time on Discourse.

If the properties you want from your JSON object are nested, you can use periods. So for example if the API returned a different structure like this:

{
  "user": {
    "id": 1234,
    "email": {
      "address": "test@example.com"
    }
  }
}

You could use user.id for the oauth2_json_user_id_path and user.email.address for oauth2_json_email_path.

If the key itself includes periods, you will need to put double quotes around it, or escape the periods with a backslash. For example, given this JSON:

{
  "example.com/uid": "myuid"
}

You would specify the path as example\.com/uid or "example.com/uid"

:warning: Warning - if you set oauth2_json_email_path, the OAuth2 provider must confirm the user owns that email address. Failure to do this can result in account takeover in Discourse!

CHANGELOG

  • 2019-03-01 A new site setting has been added to allow email addresses to be updated on Oauth2 login. The setting is called oauth2_overrides_email .
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Hi Robin, quick question:

The callback URL I have been using is https://1.hosted-by-discourse.com/auth/oauth2_basic/callback - and it doesn’t seem to be working. Does it look like I’m doing anything wrong?

What is supposed to go in “DISCOURSE_HOST”? I am currently using the Discourse hosting free trial so for the “DISCOURSE_HOST” section I am using the Discourse hosting URL - which looks like this 1.hosted-by-discourse.com

Thanks

You need to use your public site URL (whatever appears in the address bar of your browser). The *.hosted-by-discourse.com addresses are our CNAME targets, and cannot be accessed directly.

Ok, thanks David, we’ll try that and let you know how it goes by tomorrow :slight_smile:

The new callback URL worked!

But I do have another question - is it ok to leave these 2 fields (below) empty if the response to my token request doesn’t have any property such as a user id?

As you can see, I am using (or at least trying to) use the “Fetch user JSON for OAuth2” method, so I guess we can fetch the user id from that user info JSON response?

Ty!

1 Like

Yup, you can leave both of those settings blank :+1:

1 Like

Hi everyone, I just setup another topic in which I want to understand, how to setup everything for Auth0 (which already works in vanilla style), but “nicer” according to my needs.

Since I thought it is a separate topic, I created this one here. Would be great, if you could check it out. :slight_smile: