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Configuring Synapse to authenticate against an OpenID Connect provider

Synapse can be configured to use an OpenID Connect Provider (OP) for authentication, instead of its own local password database.

Any OP should work with Synapse, as long as it supports the authorization code flow. There are a few options for that:

  • start a local OP. Synapse has been tested with Hydra and Dex. Note that for an OP to work, it should be served under a secure (HTTPS) origin. A certificate signed with a self-signed, locally trusted CA should work. In that case, start Synapse with a SSL_CERT_FILE environment variable set to the path of the CA.

  • set up a SaaS OP, like Google, Auth0 or Okta. Synapse has been tested with Auth0 and Google.

It may also be possible to use other OAuth2 providers which provide the authorization code grant type, such as Github.

Preparing Synapse

The OpenID integration in Synapse uses the authlib library, which must be installed as follows:

  • The relevant libraries are included in the Docker images and Debian packages provided by matrix.org so no further action is needed.

  • If you installed Synapse into a virtualenv, run /path/to/env/bin/pip install matrix-synapse[oidc] to install the necessary dependencies.

  • For other installation mechanisms, see the documentation provided by the maintainer.

To enable the OpenID integration, you should then add a section to the oidc_providers setting in your configuration file (or uncomment one of the existing examples). See sample_config.yaml for some sample settings, as well as the text below for example configurations for specific providers.

Sample configs

Here are a few configs for providers that should work with Synapse.

Microsoft Azure Active Directory

Azure AD can act as an OpenID Connect Provider. Register a new application under App registrations in the Azure AD management console. The RedirectURI for your application should point to your matrix server: [synapse public baseurl]/_synapse/oidc/callback

Go to Certificates & secrets and register a new client secret. Make note of your Directory (tenant) ID as it will be used in the Azure links. Edit your Synapse config file and change the oidc_config section:

oidc_providers:
  - idp_id: microsoft
    idp_name: Microsoft
    issuer: "https://login.microsoftonline.com/<tenant id>/v2.0"
    client_id: "<client id>"
    client_secret: "<client secret>"
    scopes: ["openid", "profile"]
    authorization_endpoint: "https://login.microsoftonline.com/<tenant id>/oauth2/v2.0/authorize"
    token_endpoint: "https://login.microsoftonline.com/<tenant id>/oauth2/v2.0/token"
    userinfo_endpoint: "https://graph.microsoft.com/oidc/userinfo"

    user_mapping_provider:
      config:
        localpart_template: "{{ user.preferred_username.split('@')[0] }}"
        display_name_template: "{{ user.name }}"

Dex

Dex is a simple, open-source, certified OpenID Connect Provider. Although it is designed to help building a full-blown provider with an external database, it can be configured with static passwords in a config file.

Follow the Getting Started guide to install Dex.

Edit examples/config-dev.yaml config file from the Dex repo to add a client:

staticClients:
- id: synapse
  secret: secret
  redirectURIs:
  - '[synapse public baseurl]/_synapse/oidc/callback'
  name: 'Synapse'

Run with dex serve examples/config-dev.yaml.

Synapse config:

oidc_providers:
  - idp_id: dex
    idp_name: "My Dex server"
    skip_verification: true # This is needed as Dex is served on an insecure endpoint
    issuer: "http://127.0.0.1:5556/dex"
    client_id: "synapse"
    client_secret: "secret"
    scopes: ["openid", "profile"]
    user_mapping_provider:
      config:
        localpart_template: "{{ user.name }}"
        display_name_template: "{{ user.name|capitalize }}"

Keycloak

Keycloak is an opensource IdP maintained by Red Hat.

Follow the Getting Started Guide to install Keycloak and set up a realm.

  1. Click Clients in the sidebar and click Create

  2. Fill in the fields as below:

Field Value
Client ID synapse
Client Protocol openid-connect
  1. Click Save
  2. Fill in the fields as below:
Field Value
Client ID synapse
Enabled On
Client Protocol openid-connect
Access Type confidential
Valid Redirect URIs [synapse public baseurl]/_synapse/oidc/callback
  1. Click Save
  2. On the Credentials tab, update the fields:
Field Value
Client Authenticator Client ID and Secret
  1. Click Regenerate Secret
  2. Copy Secret
oidc_providers:
  - idp_id: keycloak
    idp_name: "My KeyCloak server"
    issuer: "https://127.0.0.1:8443/auth/realms/{realm_name}"
    client_id: "synapse"
    client_secret: "copy secret generated from above"
    scopes: ["openid", "profile"]
    user_mapping_provider:
      config:
        localpart_template: "{{ user.preferred_username }}"
        display_name_template: "{{ user.name }}"

Auth0

  1. Create a regular web application for Synapse

  2. Set the Allowed Callback URLs to [synapse public baseurl]/_synapse/oidc/callback

  3. Add a rule to add the preferred_username claim.

    Code sample 
    function addPersistenceAttribute(user, context, callback) {
  user.user_metadata = user.user_metadata || {};
  user.user_metadata.preferred_username = user.user_metadata.preferred_username || user.user_id;
  context.idToken.preferred_username = user.user_metadata.preferred_username;

  auth0.users.updateUserMetadata(user.user_id, user.user_metadata)
    .then(function(){
        callback(null, user, context);
    })
    .catch(function(err){
        callback(err);
    });
}

Synapse config:

oidc_providers:
  - idp_id: auth0
    idp_name: Auth0
    issuer: "https://your-tier.eu.auth0.com/" # TO BE FILLED
    client_id: "your-client-id" # TO BE FILLED
    client_secret: "your-client-secret" # TO BE FILLED
    scopes: ["openid", "profile"]
    user_mapping_provider:
      config:
        localpart_template: "{{ user.preferred_username }}"
        display_name_template: "{{ user.name }}"

GitHub

GitHub is a bit special as it is not an OpenID Connect compliant provider, but just a regular OAuth2 provider.

The /user API endpoint can be used to retrieve information on the authenticated user. As the Synapse login mechanism needs an attribute to uniquely identify users, and that endpoint does not return a sub property, an alternative subject_claim has to be set.

  1. Create a new OAuth application: https://github.com/settings/applications/new.
  2. Set the callback URL to [synapse public baseurl]/_synapse/oidc/callback.

Synapse config:

oidc_providers:
  - idp_id: github
    idp_name: Github
    discover: false
    issuer: "https://github.com/"
    client_id: "your-client-id" # TO BE FILLED
    client_secret: "your-client-secret" # TO BE FILLED
    authorization_endpoint: "https://github.com/login/oauth/authorize"
    token_endpoint: "https://github.com/login/oauth/access_token"
    userinfo_endpoint: "https://api.github.com/user"
    scopes: ["read:user"]
    user_mapping_provider:
      config:
        subject_claim: "id"
        localpart_template: "{{ user.login }}"
        display_name_template: "{{ user.name }}"

Google

  1. Set up a project in the Google API Console (see https://developers.google.com/identity/protocols/oauth2/openid-connect#appsetup).
  2. add an "OAuth Client ID" for a Web Application under "Credentials".
  3. Copy the Client ID and Client Secret, and add the following to your synapse config: 
    oidc_providers:
  - idp_id: google
    idp_name: Google
    issuer: "https://accounts.google.com/"
    client_id: "your-client-id" # TO BE FILLED
    client_secret: "your-client-secret" # TO BE FILLED
    scopes: ["openid", "profile"]
    user_mapping_provider:
      config:
        localpart_template: "{{ user.given_name|lower }}"
        display_name_template: "{{ user.name }}"
  4. Back in the Google console, add this Authorized redirect URI: [synapse public baseurl]/_synapse/oidc/callback.

Twitch

  1. Setup a developer account on Twitch
  2. Obtain the OAuth 2.0 credentials by creating an app
  3. Add this OAuth Redirect URL: [synapse public baseurl]/_synapse/oidc/callback

Synapse config:

oidc_providers:
  - idp_id: twitch
    idp_name: Twitch
    issuer: "https://id.twitch.tv/oauth2/"
    client_id: "your-client-id" # TO BE FILLED
    client_secret: "your-client-secret" # TO BE FILLED
    client_auth_method: "client_secret_post"
    user_mapping_provider:
      config:
        localpart_template: "{{ user.preferred_username }}"
        display_name_template: "{{ user.name }}"

GitLab

  1. Create a new application.
  2. Add the read_user and openid scopes.
  3. Add this Callback URL: [synapse public baseurl]/_synapse/oidc/callback

Synapse config:

oidc_providers:
  - idp_id: gitlab
    idp_name: Gitlab
    issuer: "https://gitlab.com/"
    client_id: "your-client-id" # TO BE FILLED
    client_secret: "your-client-secret" # TO BE FILLED
    client_auth_method: "client_secret_post"
    scopes: ["openid", "read_user"]
    user_profile_method: "userinfo_endpoint"
    user_mapping_provider:
      config:
        localpart_template: '{{ user.nickname }}'
        display_name_template: '{{ user.name }}'

Facebook

Like Github, Facebook provide a custom OAuth2 API rather than an OIDC-compliant one so requires a little more configuration.

  1. You will need a Facebook developer account. You can register for one here.
  2. On the apps page of the developer console, "Create App", and choose "Build Connected Experiences".
  3. Once the app is created, add "Facebook Login" and choose "Web". You don't need to go through the whole form here.
  4. In the left-hand menu, open "Products"/"Facebook Login"/"Settings".
    • Add [synapse public baseurl]/_synapse/oidc/callback as an OAuth Redirect URL.
  5. In the left-hand menu, open "Settings/Basic". Here you can copy the "App ID" and "App Secret" for use below.

Synapse config:

  - idp_id: facebook
    idp_name: Facebook
    idp_brand: "org.matrix.facebook"  # optional: styling hint for clients
    discover: false
    issuer: "https://facebook.com"
    client_id: "your-client-id" # TO BE FILLED
    client_secret: "your-client-secret" # TO BE FILLED
    scopes: ["openid", "email"]
    authorization_endpoint: https://facebook.com/dialog/oauth
    token_endpoint: https://graph.facebook.com/v9.0/oauth/access_token
    user_profile_method: "userinfo_endpoint"
    userinfo_endpoint: "https://graph.facebook.com/v9.0/me?fields=id,name,email,picture"
    user_mapping_provider:
      config:
        subject_claim: "id"
        display_name_template: "{{ user.name }}"

Relevant documents: