chore: instrument external oauth2 requests (#11519)

* chore: instrument external oauth2 requests

External requests made by oauth2 configs are now instrumented into prometheus metrics.

coderd/httpmw/apikey.go

@@ -22,6 +22,7 @@ import (
 	"github.com/coder/coder/v2/coderd/database/dbauthz"
 	"github.com/coder/coder/v2/coderd/database/dbtime"
 	"github.com/coder/coder/v2/coderd/httpapi"
+	"github.com/coder/coder/v2/coderd/promoauth"
 	"github.com/coder/coder/v2/coderd/rbac"
 	"github.com/coder/coder/v2/codersdk"
 )
@@ -74,8 +75,8 @@ func UserAuthorization(r *http.Request) Authorization {
 // OAuth2Configs is a collection of configurations for OAuth-based authentication.
 // This should be extended to support other authentication types in the future.
 type OAuth2Configs struct {
-	Github OAuth2Config
-	OIDC   OAuth2Config
+	Github promoauth.OAuth2Config
+	OIDC   promoauth.OAuth2Config
 }
 
 func (c *OAuth2Configs) IsZero() bool {
@@ -270,7 +271,7 @@ func ExtractAPIKey(rw http.ResponseWriter, r *http.Request, cfg ExtractAPIKeyCon
 				})
 			}
 
-			var oauthConfig OAuth2Config
+			var oauthConfig promoauth.OAuth2Config
 			switch key.LoginType {
 			case database.LoginTypeGithub:
 				oauthConfig = cfg.OAuth2Configs.Github

coderd/httpmw/oauth2.go

@@ -10,6 +10,7 @@ import (
 
 	"github.com/coder/coder/v2/coderd/database"
 	"github.com/coder/coder/v2/coderd/httpapi"
+	"github.com/coder/coder/v2/coderd/promoauth"
 	"github.com/coder/coder/v2/codersdk"
 	"github.com/coder/coder/v2/cryptorand"
 )
@@ -22,14 +23,6 @@ type OAuth2State struct {
 	StateString string
 }
 
-// OAuth2Config exposes a subset of *oauth2.Config functions for easier testing.
-// *oauth2.Config should be used instead of implementing this in production.
-type OAuth2Config interface {
-	AuthCodeURL(state string, opts ...oauth2.AuthCodeOption) string
-	Exchange(ctx context.Context, code string, opts ...oauth2.AuthCodeOption) (*oauth2.Token, error)
-	TokenSource(context.Context, *oauth2.Token) oauth2.TokenSource
-}
-
 // OAuth2 returns the state from an oauth request.
 func OAuth2(r *http.Request) OAuth2State {
 	oauth, ok := r.Context().Value(oauth2StateKey{}).(OAuth2State)
@@ -44,7 +37,7 @@ func OAuth2(r *http.Request) OAuth2State {
 // a "code" URL parameter will be redirected.
 // AuthURLOpts are passed to the AuthCodeURL function. If this is nil,
 // the default option oauth2.AccessTypeOffline will be used.
-func ExtractOAuth2(config OAuth2Config, client *http.Client, authURLOpts map[string]string) func(http.Handler) http.Handler {
+func ExtractOAuth2(config promoauth.OAuth2Config, client *http.Client, authURLOpts map[string]string) func(http.Handler) http.Handler {
 	opts := make([]oauth2.AuthCodeOption, 0, len(authURLOpts)+1)
 	opts = append(opts, oauth2.AccessTypeOffline)
 	for k, v := range authURLOpts {