feat: add email scope to OAuth configuration and update documentation

server/internal/config/member.go

@@ -152,7 +152,7 @@ func (Member) Init(cmd *cobra.Command) error {
 		return err
 	}
 
-	cmd.PersistentFlags().StringSlice("member.oauth.scopes", []string{"openid", "profile"}, "OAuth 2.0 scopes")
+	cmd.PersistentFlags().StringSlice("member.oauth.scopes", []string{"openid", "profile", "email"}, "OAuth 2.0 scopes")
 	if err := viper.BindPFlag("member.oauth.scopes", cmd.PersistentFlags().Lookup("member.oauth.scopes")); err != nil {
 		return err
 	}

server/internal/member/oauth/service.go

@@ -13,6 +13,8 @@ import (
 	"sync"
 	"time"
 
+	"github.com/rs/zerolog/log"
+
 	"github.com/m1k1o/neko/server/pkg/types"
 )
 
@@ -166,6 +168,10 @@ func (service *Service) Complete(ctx context.Context, stateToken, code string) (
 		email = claim(idClaims, "email")
 	}
 
+	if email == "" && (len(config.AdminEmails) > 0 || len(config.UserEmails) > 0) {
+		log.Warn().Msg("OAuth admin_emails/user_emails are configured but the provider did not return an 'email' claim; request the 'email' scope")
+	}
+
 	isAdmin := boolClaim(claims, "isAdmin") || boolClaim(idClaims, "isAdmin")
 	admin := administrator(email, isAdmin, config.AdminEmails)