enable fallback secret names [ci skip]

cmd/drone-docker-gcr/main.go

@@ -8,12 +8,19 @@ import (
 	"strings"
 )
 
+// gcr default username
+const username = "_json_key"
+
 func main() {
 	var (
-		username = "_json_key"
-		password = os.Getenv("GCR_TOKEN")
-		registry = os.Getenv("PLUGIN_REGISTRY")
-		repo     = os.Getenv("PLUGIN_REPO")
+		repo     = getenv("PLUGIN_REPO")
+		registry = getenv("PLUGIN_REGISTRY")
+		password = getenv(
+			"PLUGIN_JSON_KEY",
+			"GCR_JSON_KEY",
+			"GOOGLE_CREDENTIALS",
+			"GOOGLE_APPLICATION_CREDENTIALS",
+		)
 	)
 
 	// decode the token if base64 encoded
@@ -32,9 +39,9 @@ func main() {
 	// should prepend.
 	if !strings.HasPrefix(repo, registry) {
 		repo = path.Join(registry, repo)
-		os.Setenv("PLUGIN_REPO", repo)
 	}
 
+	os.Setenv("PLUGIN_REPO", repo)
 	os.Setenv("PLUGIN_REGISTRY", registry)
 	os.Setenv("DOCKER_USERNAME", username)
 	os.Setenv("DOCKER_PASSWORD", password)
@@ -48,3 +55,13 @@ func main() {
 		os.Exit(1)
 	}
 }
+
+func getenv(key ...string) (s string) {
+	for _, k := range key {
+		s = os.Getenv(k)
+		if s != "" {
+			return
+		}
+	}
+	return
+}