container credentials (#868)

* Chore: add a snapshot target

* Update: support credentials for private containers

Resolves: #788

* fix: rework container credentials

Signed-off-by: hackercat <me@hackerc.at>

* fix: check if Credentials are not nil

* fix: return on missing credentials key

Co-authored-by: hackercat <me@hackerc.at>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

Makefile

@@ -104,3 +104,10 @@ ifneq ($(shell git status -s),)
 endif
 	git tag -a -m "releasing v$(NEW_VERSION)" v$(NEW_VERSION)
 	git push origin v$(NEW_VERSION)
+
+.PHONY: snapshot
+snapshot:
+	goreleaser build \
+		--rm-dist \
+		--single-target \
+		--snapshot

pkg/model/workflow.go

@@ -295,15 +295,16 @@ func commonKeysMatch(a map[string]interface{}, b map[string]interface{}) bool {
 
 // ContainerSpec is the specification of the container to use for the job
 type ContainerSpec struct {
-	Image      string            `yaml:"image"`
-	Env        map[string]string `yaml:"env"`
-	Ports      []string          `yaml:"ports"`
-	Volumes    []string          `yaml:"volumes"`
-	Options    string            `yaml:"options"`
-	Entrypoint string
-	Args       string
-	Name       string
-	Reuse      bool
+	Image       string            `yaml:"image"`
+	Env         map[string]string `yaml:"env"`
+	Ports       []string          `yaml:"ports"`
+	Volumes     []string          `yaml:"volumes"`
+	Options     string            `yaml:"options"`
+	Credentials map[string]string `yaml:"credentials"`
+	Entrypoint  string
+	Args        string
+	Name        string
+	Reuse       bool
 }
 
 // Step is the structure of one step in a job

pkg/model/workflow_test.go

@@ -99,6 +99,36 @@ jobs:
 	assert.Contains(t, workflow.Jobs["test2"].Container().Env["foo"], "bar")
 }
 
+func TestReadWorkflow_ObjectContainer(t *testing.T) {
+	yaml := `
+name: local-action-docker-url
+
+jobs:
+  test:
+    container:
+      image: r.example.org/something:latest
+      credentials:
+        username: registry-username
+        password: registry-password
+      env:
+        HOME: /home/user
+    runs-on: ubuntu-latest
+    steps:
+    - uses: ./actions/docker-url
+`
+
+	workflow, err := ReadWorkflow(strings.NewReader(yaml))
+	assert.NoError(t, err, "read workflow should succeed")
+	assert.Len(t, workflow.Jobs, 1)
+
+	container := workflow.GetJob("test").Container()
+
+	assert.Contains(t, container.Image, "r.example.org/something:latest")
+	assert.Contains(t, container.Env["HOME"], "/home/user")
+	assert.Contains(t, container.Credentials["username"], "registry-username")
+	assert.Contains(t, container.Credentials["password"], "registry-password")
+}
+
 func TestReadWorkflow_StepsTypes(t *testing.T) {
 	yaml := `
 name: invalid step definition

pkg/runner/run_context.go

@@ -153,6 +153,11 @@ func (rc *RunContext) startJobContainer() common.Executor {
 			return true
 		})
 
+		username, password, err := rc.handleCredentials()
+		if err != nil {
+			return fmt.Errorf("failed to handle credentials: %s", err)
+		}
+
 		common.Logger(ctx).Infof("\U0001f680  Start image=%s", image)
 		name := rc.jobContainerName()
 
@@ -169,8 +174,8 @@ func (rc *RunContext) startJobContainer() common.Executor {
 			Entrypoint:  []string{"/usr/bin/tail", "-f", "/dev/null"},
 			WorkingDir:  rc.Config.ContainerWorkdir(),
 			Image:       image,
-			Username:    rc.Config.Secrets["DOCKER_USERNAME"],
-			Password:    rc.Config.Secrets["DOCKER_PASSWORD"],
+			Username:    username,
+			Password:    password,
 			Name:        name,
 			Env:         envList,
 			Mounts:      mounts,
@@ -836,3 +841,37 @@ func (rc *RunContext) localCheckoutPath() (string, bool) {
 	}
 	return "", false
 }
+
+func (rc *RunContext) handleCredentials() (username, password string, err error) {
+	// TODO: remove below 2 lines when we can release act with breaking changes
+	username = rc.Config.Secrets["DOCKER_USERNAME"]
+	password = rc.Config.Secrets["DOCKER_PASSWORD"]
+
+	container := rc.Run.Job().Container()
+	if container == nil || container.Credentials == nil {
+		return
+	}
+
+	if container.Credentials != nil && len(container.Credentials) != 2 {
+		err = fmt.Errorf("invalid property count for key 'credentials:'")
+		return
+	}
+
+	ee := rc.NewExpressionEvaluator()
+	var ok bool
+	if username, ok = ee.InterpolateWithStringCheck(container.Credentials["username"]); !ok {
+		err = fmt.Errorf("failed to interpolate container.credentials.username")
+		return
+	}
+	if password, ok = ee.InterpolateWithStringCheck(container.Credentials["password"]); !ok {
+		err = fmt.Errorf("failed to interpolate container.credentials.password")
+		return
+	}
+
+	if container.Credentials["username"] == "" || container.Credentials["password"] == "" {
+		err = fmt.Errorf("container.credentials cannot be empty")
+		return
+	}
+
+	return username, password, err
+}