feat: allow to template dockerfile (#2797)

* feat: allow to template dockerfile

Signed-off-by: Carlos A Becker <caarlos0@gmail.com>

* test: added one more test

Signed-off-by: Carlos A Becker <caarlos0@gmail.com>

internal/pipe/docker/docker.go

@@ -143,7 +143,11 @@ func process(ctx *context.Context, docker config.Docker, artifacts []*artifact.A
 	log.Debug("tempdir: " + tmp)
 
 	if docker.Use != useBuildPacks {
-		if err := gio.Copy(docker.Dockerfile, filepath.Join(tmp, "Dockerfile")); err != nil {
+		dockerfile, err := tmpl.New(ctx).Apply(docker.Dockerfile)
+		if err != nil {
+			return err
+		}
+		if err := gio.Copy(dockerfile, filepath.Join(tmp, "Dockerfile")); err != nil {
 			return fmt.Errorf("failed to copy dockerfile: %w", err)
 		}
 	}

internal/pipe/docker/docker_test.go

@@ -439,6 +439,48 @@ func TestRunPipe(t *testing.T) {
 			pubAssertError:      shouldNotErr,
 			manifestAssertError: shouldNotErr,
 		},
+		"templated-dockerfile": {
+			env: map[string]string{
+				"Dockerfile": "testdata/Dockerfile",
+			},
+			dockers: []config.Docker{
+				{
+					ImageTemplates: []string{
+						registry + "goreleaser/templated_dockerfile:v1",
+					},
+					Goos:       "linux",
+					Goarch:     "amd64",
+					Dockerfile: "{{ .Env.Dockerfile }}",
+					Files: []string{
+						"testdata/extra_file.txt",
+					},
+				},
+			},
+			expect: []string{
+				registry + "goreleaser/templated_dockerfile:v1",
+			},
+			assertError:         shouldNotErr,
+			assertImageLabels:   noLabels,
+			pubAssertError:      shouldNotErr,
+			manifestAssertError: shouldNotErr,
+		},
+		"templated-dockerfile-invalid": {
+			dockers: []config.Docker{
+				{
+					ImageTemplates: []string{
+						registry + "goreleaser/invalid-templated-dockerfile:v1",
+					},
+					Goos:       "linux",
+					Goarch:     "amd64",
+					Dockerfile: "{{ .Env.Dockerfile }}",
+				},
+			},
+			expect:              []string{},
+			assertError:         shouldErr(`template: tmpl:1:7: executing "tmpl" at <.Env.Dockerfile>: map has no entry for key "Dockerfile"`),
+			assertImageLabels:   noLabels,
+			pubAssertError:      shouldNotErr,
+			manifestAssertError: shouldNotErr,
+		},
 		"image template with env": {
 			env: map[string]string{
 				"FOO": "test_run_pipe_template",

www/docs/customization/docker.md

@@ -81,7 +81,9 @@ dockers:
     skip_push: false
 
     # Path to the Dockerfile (from the project root).
-    dockerfile: Dockerfile
+    #
+    # Defaults to `Dockerfile`.
+    dockerfile: '{{ .Env.DOCKERFILE }}'
 
     # Set the "backend" for the Docker pipe.
     # Valid options are: docker, buildx, podman, buildpacks