feat: Add OIDC authentication (#3314)

* feat: Add OIDC authentication

* Extract username into a separate package and add OIDC tests

* Add test case for invalid tokens

* Add test case for username as email

* Add OIDC to the frontend

* Improve comments from self-review

* Add authentication docs

* Add telemetry

* Update docs/install/auth.md

Co-authored-by: Ammar Bandukwala <ammar@ammar.io>

* Update docs/install/auth.md

Co-authored-by: Ammar Bandukwala <ammar@ammar.io>

* Remove username package

Co-authored-by: Ammar Bandukwala <ammar@ammar.io>

coderd/coderd.go

@@ -57,6 +57,7 @@ type Options struct {
 	AzureCertificates    x509.VerifyOptions
 	GoogleTokenValidator *idtoken.Validator
 	GithubOAuth2Config   *GithubOAuth2Config
+	OIDCConfig           *OIDCConfig
 	ICEServers           []webrtc.ICEServer
 	SecureAuthCookie     bool
 	SSHKeygenAlgorithm   gitsshkey.Algorithm
@@ -105,6 +106,7 @@ func New(options *Options) *API {
 	api.workspaceAgentCache = wsconncache.New(api.dialWorkspaceAgent, 0)
 	oauthConfigs := &httpmw.OAuth2Configs{
 		Github: options.GithubOAuth2Config,
+		OIDC:   options.OIDCConfig,
 	}
 	apiKeyMiddleware := httpmw.ExtractAPIKey(options.Database, oauthConfigs, false)
 
@@ -259,6 +261,10 @@ func New(options *Options) *API {
 					r.Get("/callback", api.userOAuth2Github)
 				})
 			})
+			r.Route("/oidc/callback", func(r chi.Router) {
+				r.Use(httpmw.ExtractOAuth2(options.OIDCConfig))
+				r.Get("/", api.userOIDC)
+			})
 			r.Group(func(r chi.Router) {
 				r.Use(
 					apiKeyMiddleware,