also supporting latest docker tag

config/config.go

@@ -167,6 +167,7 @@ type Docker struct {
 	Goarm      string `yaml:",omitempty"`
 	Image      string `yaml:",omitempty"`
 	Dockerfile string `yaml:",omitempty"`
+	Latest     bool   `yaml:",omitempty"`
 
 	// Capture all undefined fields and should be empty after loading
 	XXX map[string]interface{} `yaml:",inline"`

docs/130-docker.md

@@ -50,6 +50,8 @@ dockers:
     image: myuser/myimage
     # Path to the Dockerfile (from the project root)
     dockerfile: Dockerfile
+    # Also tag and push myuser/myimage:latest
+    latest: true
 ```
 
 These settings should allow you to generate multiple docker images, using

pipeline/docker/docker.go

@@ -62,6 +62,7 @@ func doRun(ctx *context.Context, folder string, docker config.Docker, binary con
 	var root = filepath.Join(ctx.Config.Dist, folder)
 	var dockerfile = filepath.Join(root, filepath.Base(docker.Dockerfile))
 	var image = fmt.Sprintf("%s:%s", docker.Image, ctx.Version)
+	var latest = fmt.Sprintf("%s:latest", docker.Image)
 
 	if err := os.Link(docker.Dockerfile, dockerfile); err != nil {
 		return errors.Wrap(err, "failed to link dockerfile")
@@ -69,6 +70,11 @@ func doRun(ctx *context.Context, folder string, docker config.Docker, binary con
 	if err := dockerBuild(root, dockerfile, image); err != nil {
 		return err
 	}
+	if docker.Latest {
+		if err := dockerTag(image, latest); err != nil {
+			return err
+		}
+	}
 
 	// TODO: improve this so it can log into to stdout
 	if !ctx.Publish {
@@ -80,6 +86,11 @@ func doRun(ctx *context.Context, folder string, docker config.Docker, binary con
 	if err := dockerPush(image); err != nil {
 		return err
 	}
+	if docker.Latest {
+		if err := dockerTag(image, latest); err != nil {
+			return err
+		}
+	}
 	return nil
 }
 
@@ -95,6 +106,18 @@ func dockerBuild(root, dockerfile, image string) error {
 	return nil
 }
 
+func dockerTag(image, tag string) error {
+	log.WithField("image", image).WithField("tag", tag).Info("building docker image")
+	var cmd = exec.Command("docker", "tag", image, tag)
+	log.WithField("cmd", cmd).Debug("executing")
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return errors.Wrapf(err, "failed to tag docker image: \n%s", string(out))
+	}
+	log.Debugf("docker tag output: \n%s", string(out))
+	return nil
+}
+
 func dockerPush(image string) error {
 	log.WithField("image", image).Info("pushing docker image")
 	var cmd = exec.Command("docker", "push", image)

pipeline/docker/docker_test.go

@@ -24,8 +24,14 @@ func TestRunPipe(t *testing.T) {
 	var binPath = filepath.Join(dist, "mybin", "mybin")
 	_, err = os.Create(binPath)
 	assert.NoError(err)
+	var images = []string{
+		"goreleaser/test_run_pipe:1.0.0",
+		"goreleaser/test_run_pipe:latest",
+	}
 	// this might fail as the image doesnt exist yet, so lets ignore the error
-	_ = exec.Command("docker", "rmi", "goreleaser/test_run_pipe:v1.0.0").Run()
+	for _, img := range images {
+		_ = exec.Command("docker", "rmi", img).Run()
+	}
 	var ctx = &context.Context{
 		Version: "1.0.0",
 		Publish: true,
@@ -39,6 +45,7 @@ func TestRunPipe(t *testing.T) {
 					Goarch:     "amd64",
 					Dockerfile: "testdata/Dockerfile",
 					Binary:     "mybin",
+					Latest:     true,
 				},
 				{
 					Image:      "goreleaser/test_run_pipe_nope",
@@ -54,11 +61,13 @@ func TestRunPipe(t *testing.T) {
 		ctx.AddBinary(plat, "mybin", "mybin", binPath)
 	}
 	assert.NoError(Pipe{}.Run(ctx))
+
 	// this might should not fail as the image should have been created when
 	// the step ran
-	assert.NoError(
-		exec.Command("docker", "rmi", "goreleaser/test_run_pipe:1.0.0").Run(),
-	)
+	for _, img := range images {
+		assert.NoError(exec.Command("docker", "rmi", img).Run())
+	}
+
 	// the test_run_pipe_nope image should not have been created, so deleting
 	// it should fail
 	assert.Error(