docs(oidc): firezone integration (#5125)

This adds a Firezone VPN integration with OpenID Connect 1.0.

docs/content/en/integration/openid-connect/firezone/index.md

@@ -0,0 +1,96 @@
+---
+title: "Firezone"
+description: "Integrating Firezone with the Authelia OpenID Connect Provider."
+lead: ""
+date: 2023-03-25T13:07:02+10:00
+draft: false
+images: []
+menu:
+  integration:
+    parent: "openid-connect"
+weight: 620
+toc: true
+community: true
+---
+
+## Tested Versions
+
+* [Authelia]
+  * [v4.37.5](https://github.com/authelia/authelia/releases/tag/v4.37.5)
+* [Firezone]
+  * [0.7.25](https://github.com/firezone/firezone/releases/tag/0.7.25)
+
+## Before You Begin
+
+{{% oidc-common %}}
+
+### Assumptions
+
+This example makes the following assumptions:
+
+* __Application Root URL:__ `https://firezone.example.com`
+* __Authelia Root URL:__ `https://auth.example.com`
+* __Client ID:__ `firezone`
+* __Client Secret:__ `insecure_secret`
+* __Config ID (Firezone):__ `authelia`:
+    * This option determines the redirect URI in the format of
+      `https://firezone.example.com/auth/oidc/<Config ID>/callback`.
+      This means if you change this value you need to update the redirect URI.
+
+## Configuration
+
+### Application
+
+To configure [Firezone] to utilize Authelia as an [OpenID Connect 1.0] Provider:
+
+1. Visit your [Firezone] site
+2. Sign in as an admin
+3. Visit:
+    1. Settings
+    2. Security
+4. In the `Single Sign-On` section, click on the `Add OpenID Connect Provider` button
+5. Configure:
+   1. Config ID: `authelia`
+   2. Label: `Authelia`
+   3. Scope: `openid email profile`
+   4. Client ID: `firezone`
+   5. Client secret: `insecure_secret`
+   6. Discovery Document URI: `https://auth.example.com/.well-known/openid-configuration`
+   7. Redirect URI (optional): `https://firezone.example.com/auth/oidc/authelia/callback`
+   8. Auto-create users (checkbox): `true`
+
+{{< figure src="firezone.png" alt="Firezone" width="500" >}}
+
+Take a look at the [See Also](#see-also) section for the cheatsheets corresponding to the sections above for their
+descriptions.
+
+### Authelia
+
+The following YAML configuration is an example __Authelia__
+[client configuration](../../../configuration/identity-providers/open-id-connect.md#clients) for use with [Firezone] which
+will operate with the above example:
+
+```yaml
+- id: firezone
+  description: Firezone
+  secret: '$pbkdf2-sha512$310000$c8p78n7pUMln0jzvd4aK4Q$JNRBzwAo0ek5qKn50cFzzvE9RXV88h1wJn5KGiHrD0YKtZaR/nCb2CJPOsKaPK0hjf.9yHxzQGZziziccp6Yng'  # The digest of 'insecure_secret'.
+  public: false
+  authorization_policy: two_factor
+  enforce_pkce: true
+  pkce_challenge_method: S256
+  redirect_uris:
+    - https://firezone.example.com/auth/oidc/authelia/callback
+  scopes:
+    - openid
+    - email
+    - profile
+  userinfo_signing_algorithm: none
+```
+
+## See Also
+
+- [Firezone OIDC documentation](https://www.firezone.dev/docs/authenticate/oidc/)
+
+[Authelia]: https://www.authelia.com
+[Firezone]: https://www.firezone.dev
+[OpenID Connect 1.0]: ../../openid-connect/introduction.md