Switch to service account key

Change-Id: I33d0eccb3f9087d339323ca35a425dff2416b9d4

.gitattributes

@@ -1 +1 @@
-groups/client_id.json   filter=git-crypt diff=git-crypt
+groups/*.json   filter=git-crypt diff=git-crypt

groups/reconcile.go

@@ -76,21 +76,24 @@ func saveToken(path string, token *oauth2.Token) {
 }
 
 func main() {
-	b, err := ioutil.ReadFile("client_id.json")
+	jsonCredentials, err := ioutil.ReadFile("k8s-infra-test-project-1896690daeb3.json")
 	if err != nil {
-		log.Fatalf("Unable to read client secret file: %v", err)
+		panic(fmt.Sprintf("error reading credentials from file: %v", err))
 	}
 
-	// If modifying these scopes, delete your previously saved token.json.
-	config, err := google.ConfigFromJSON(b, admin.AdminDirectoryUserReadonlyScope,
+	config, err := google.JWTConfigFromJSON(jsonCredentials, admin.AdminDirectoryUserReadonlyScope,
 		admin.AdminDirectoryGroupScope,
 		admin.AdminDirectoryGroupMemberScope,
 		groupssettings.AppsGroupsSettingsScope)
 	if err != nil {
-		log.Fatalf("Unable to parse client secret file to config: %v", err)
+		panic(fmt.Sprintf("Unable to parse client secret file to config: %v\n. " +
+			"Please run 'git-crypt unlock'", err))
 	}
-	client := getClient(config)
+	config.Subject = "wg-k8s-infra-api-test@kubernetes.io"
 
+	ctx := context.Background()
+
+	client := config.Client(ctx)
 	srv, err := admin.New(client)
 	if err != nil {
 		log.Fatalf("Unable to retrieve directory Client %v", err)