Added support to build and publish GCR image

cmd/kaniko-docker/main.go

@@ -120,13 +120,13 @@ func run(c *cli.Context) error {
 // Create the docker config file for authentication
 func createDockerCfgFile(username, password, registry string) error {
 	if username == "" {
-		return fmt.Errorf("Username is not set")
+		return fmt.Errorf("Username must be specified")
 	}
 	if password == "" {
-		return fmt.Errorf("Password is not set")
+		return fmt.Errorf("Password must be specified")
 	}
 	if registry == "" {
-		return fmt.Errorf("Registry is not set")
+		return fmt.Errorf("Registry must be specified")
 	}
 
 	authBytes := []byte(fmt.Sprintf("%s:%s", username, password))

cmd/kaniko-gcr/main.go

@@ -0,0 +1,131 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+
+	"github.com/joho/godotenv"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+	"github.com/urfave/cli"
+
+	kaniko "github.com/drone/drone-kaniko"
+)
+
+const (
+	// GCR JSON key file path
+	gcrKeyPath string = "/kaniko/gcr.json"
+)
+
+var (
+	version = "unknown"
+)
+
+func main() {
+	// Load env-file if it exists first
+	if env := os.Getenv("PLUGIN_ENV_FILE"); env != "" {
+		godotenv.Load(env)
+	}
+
+	app := cli.NewApp()
+	app.Name = "kaniko gcr plugin"
+	app.Usage = "kaniko gcr plugin"
+	app.Action = run
+	app.Version = version
+	app.Flags = []cli.Flag{
+		cli.StringFlag{
+			Name:   "dockerfile",
+			Usage:  "build dockerfile",
+			Value:  "Dockerfile",
+			EnvVar: "PLUGIN_DOCKERFILE",
+		},
+		cli.StringFlag{
+			Name:   "context",
+			Usage:  "build context",
+			Value:  ".",
+			EnvVar: "PLUGIN_CONTEXT",
+		},
+		cli.StringSliceFlag{
+			Name:     "tags",
+			Usage:    "build tags",
+			Value:    &cli.StringSlice{"latest"},
+			EnvVar:   "PLUGIN_TAGS",
+			FilePath: ".tags",
+		},
+		cli.StringSliceFlag{
+			Name:   "args",
+			Usage:  "build args",
+			EnvVar: "PLUGIN_BUILD_ARGS",
+		},
+		cli.StringFlag{
+			Name:   "target",
+			Usage:  "build target",
+			EnvVar: "PLUGIN_TARGET",
+		},
+		cli.StringFlag{
+			Name:   "repo",
+			Usage:  "gcr repository",
+			EnvVar: "PLUGIN_REPO",
+		},
+		cli.StringSliceFlag{
+			Name:   "custom-labels",
+			Usage:  "additional k=v labels",
+			EnvVar: "PLUGIN_CUSTOM_LABELS",
+		},
+		cli.StringFlag{
+			Name:   "registry",
+			Usage:  "gcr registry",
+			Value:  "gcr.io",
+			EnvVar: "PLUGIN_REGISTRY",
+		},
+		cli.StringFlag{
+			Name:   "json-key",
+			Usage:  "docker username",
+			EnvVar: "PLUGIN_JSON_KEY",
+		},
+	}
+
+	if err := app.Run(os.Args); err != nil {
+		logrus.Fatal(err)
+	}
+}
+
+func run(c *cli.Context) error {
+	err := setupGCRAuth(c.String("json-key"))
+	if err != nil {
+		return err
+	}
+
+	if c.String("repo") == "" {
+		return fmt.Errorf("repo must be specified")
+	}
+
+	plugin := kaniko.Plugin{
+		Build: kaniko.Build{
+			Dockerfile: c.String("dockerfile"),
+			Context:    c.String("context"),
+			Tags:       c.StringSlice("tags"),
+			Args:       c.StringSlice("args"),
+			Target:     c.String("target"),
+			Repo:       fmt.Sprintf("%s/%s", c.String("registry"), c.String("repo")),
+			Labels:     c.StringSlice("custom-labels"),
+		},
+	}
+	return plugin.Exec()
+}
+
+// Create the docker config file for authentication
+func setupGCRAuth(jsonKey string) error {
+	if jsonKey == "" {
+		return fmt.Errorf("GCR JSON key must be specified")
+	}
+
+	err := ioutil.WriteFile(gcrKeyPath, []byte(jsonKey), 0644)
+	if err != nil {
+		return errors.Wrap(err, "failed to write GCR JSON key")
+	}
+
+	os.Setenv("GOOGLE_APPLICATION_CREDENTIALS", gcrKeyPath)
+	return nil
+}