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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][hydra] and
+ [Dex][dex-idp]. 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][google-idp], [Auth0][auth0] or
+ [Okta][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](https://tools.ietf.org/html/rfc6749#section-4.1),
+such as [Github][github-idp].
+
+[google-idp]: https://developers.google.com/identity/protocols/oauth2/openid-connect
+[auth0]: https://auth0.com/
+[okta]: https://www.okta.com/
+[dex-idp]: https://github.com/dexidp/dex
+[hydra]: https://www.ory.sh/docs/hydra/
+[github-idp]: https://developer.github.com/apps/building-oauth-apps/authorizing-oauth-apps
+
+## Preparing Synapse
+
+The OpenID integration in Synapse uses the
+[`authlib`](https://pypi.org/project/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 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 an `oidc_config` section
+to your configuration file (or uncomment the `enabled: true` line in the
+existing section). See [sample_config.yaml](./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.
+
+### [Dex][dex-idp]
+
+[Dex][dex-idp] 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](https://github.com/dexidp/dex/blob/master/Documentation/getting-started.md)
+to install Dex.
+
+Edit `examples/config-dev.yaml` config file from the Dex repo to add a client:
+
+```yaml
+staticClients:
+- id: synapse
+ secret: secret
+ redirectURIs:
+ - '[synapse public baseurl]/_synapse/oidc/callback'
+ name: 'Synapse'
+```
+
+Run with `dex serve examples/config-dex.yaml`.
+
+Synapse config:
+
+```yaml
+oidc_config:
+ enabled: true
+ 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 }}"
+```
+
+### [Auth0][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.
+ <details>
+ <summary>Code sample</summary>
+
+ ```js
+ 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);
+ });
+ }
+ ```
+ </details>
+
+Synapse config:
+
+```yaml
+oidc_config:
+ enabled: true
+ 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](https://developer.github.com/v3/users/#get-the-authenticated-user)
+can be used to retrieve information on the authenticated user. As the Synaspse
+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:
+
+```yaml
+oidc_config:
+ enabled: true
+ 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][google-idp]
+
+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:
+ ```yaml
+ oidc_config:
+ enabled: true
+ 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](https://dev.twitch.tv/)
+2. Obtain the OAuth 2.0 credentials by [creating an app](https://dev.twitch.tv/console/apps/)
+3. Add this OAuth Redirect URL: `[synapse public baseurl]/_synapse/oidc/callback`
+
+Synapse config:
+
+```yaml
+oidc_config:
+ enabled: true
+ 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 }}'
+```
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