Support setting shell via defaults.run (#343)

Note that we don't support the more general use of defaults, just its
run key for setting shell and working directory.

The documentation for defaults.run is here:
  https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#defaultsrun

Fixes #214.

Co-authored-by: Casey Lee <cplee@nektos.com>

pkg/model/workflow.go

@@ -17,6 +17,7 @@ type Workflow struct {
 	RawOn    yaml.Node         `yaml:"on"`
 	Env      map[string]string `yaml:"env"`
 	Jobs     map[string]*Job   `yaml:"jobs"`
+	Defaults Defaults          `yaml:"defaults"`
 }
 
 // On events for the workflow
@@ -64,6 +65,7 @@ type Job struct {
 	Services       map[string]*ContainerSpec `yaml:"services"`
 	Strategy       *Strategy                 `yaml:"strategy"`
 	RawContainer   yaml.Node                 `yaml:"container"`
+	Defaults       Defaults                  `yaml:"defaults"`
 }
 
 // Strategy for the job
@@ -73,6 +75,17 @@ type Strategy struct {
 	Matrix      map[string][]interface{} `yaml:"matrix"`
 }
 
+// Default settings that will apply to all steps in the job or workflow
+type Defaults struct {
+	Run RunDefaults `yaml:"run"`
+}
+
+// Defaults for all run steps in the job or workflow
+type RunDefaults struct {
+	Shell            string `yaml:"shell"`
+	WorkingDirectory string `yaml:"working-directory"`
+}
+
 // Container details for the job
 func (j *Job) Container() *ContainerSpec {
 	var val *ContainerSpec

pkg/runner/runner_test.go

@@ -55,6 +55,7 @@ func TestRunEvent(t *testing.T) {
 		{"commands", "push", ""},
 		{"workdir", "push", ""},
 		{"issue-228", "push", ""}, // TODO [igni]: Remove this once everything passes
+		{"defaults-run", "push", ""},
 	}
 	log.SetLevel(log.DebugLevel)
 

pkg/runner/step_context.go

@@ -111,6 +111,12 @@ func (sc *StepContext) setupShellCommand() common.Executor {
 			return err
 		}
 
+		if step.WorkingDirectory == "" {
+			step.WorkingDirectory = rc.Run.Job().Defaults.Run.WorkingDirectory
+		}
+		if step.WorkingDirectory == "" {
+			step.WorkingDirectory = rc.Run.Workflow.Defaults.Run.WorkingDirectory
+		}
 		if step.WorkingDirectory != "" {
 			_, err = script.WriteString(fmt.Sprintf("cd %s\n", step.WorkingDirectory))
 			if err != nil {
@@ -126,6 +132,13 @@ func (sc *StepContext) setupShellCommand() common.Executor {
 		scriptName := fmt.Sprintf("workflow/%s", step.ID)
 		log.Debugf("Wrote command '%s' to '%s'", run, scriptName)
 		containerPath := fmt.Sprintf("/github/%s", scriptName)
+
+		if step.Shell == "" {
+			step.Shell = rc.Run.Job().Defaults.Run.Shell
+		}
+		if step.Shell == "" {
+			step.Shell = rc.Run.Workflow.Defaults.Run.Shell
+		}
 		sc.Cmd = strings.Fields(strings.Replace(step.ShellCommand(), "{0}", containerPath, 1))
 		return rc.JobContainer.Copy("/github/", &container.FileEntry{
 			Name: scriptName,

pkg/runner/testdata/defaults-run/main.yaml

@@ -0,0 +1,29 @@
+name: defaults-run
+on:
+  - push
+defaults:
+  run:
+    shell: sh
+jobs:
+  without-defaults:
+    runs-on: ubuntu-latest
+    steps:
+    - run: echo $SHELL | grep -v bash || exit 1
+  with-defaults:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        shell: bash
+        working-directory: /tmp
+    steps:
+    - run: |
+        echo $SHELL | grep bash || exit 1
+        [ $(pwd) = /tmp ] || exit 2
+  override-in-step:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        shell: bash
+    steps:
+    - run: echo $SHELL | grep -v bash || exit 1
+      shell: sh