Implement `parallel' (just alias of run_after)

README.md

@@ -94,6 +94,27 @@ The following is the parameter of Shell script stage.
 |:----------------:|:----------:|:--------------------------------------:|
 |   file           | false      | shell script file run in the stage     |
 
+## Parallel stages
+
+ You can set child stages and run these stages in parallel like this.
+
+```yaml
+pipeline:
+  - name: parallel stages
+    parallel:
+      - name: parallel command 1
+        type: command
+        command: parallel command 1
+      - name: parallel command 2
+        type: command
+        command: parallel command 2
+      - name: parallel command 3
+        type: command
+        command: parallel command 3
+```
+
+`parallel command 1`, `parallel command 2` and `parallel command 3` are executed in parallel.
+
 ## Cleanup pipeline
 
 Walter configuraiton can have one **cleanup** block; cleanup is another pipeline which needs to be executed after a pipeline has either failed or passed.

config/parser.go

@@ -219,9 +219,16 @@ func mapStage(stageMap map[interface{}]interface{}, envs *EnvVariables) (stages.
 		}
 	}
 
-	if runAfters := stageMap["run_after"]; runAfters != nil {
-		for _, runAfter := range runAfters.([]interface{}) {
-			childStage, err := mapStage(runAfter.(map[interface{}]interface{}), envs)
+	parallelStages := stageMap["parallel"]
+	if parallelStages == nil {
+		if parallelStages = stageMap["run_after"]; parallelStages != nil {
+			log.Warn("`run_after' will be obsoleted in near future. Use `parallel' instead.")
+		}
+	}
+
+	if parallelStages != nil {
+		for _, parallelStages := range parallelStages.([]interface{}) {
+			childStage, err := mapStage(parallelStages.(map[interface{}]interface{}), envs)
 			if err != nil {
 				return nil, err
 			}

config/parser_test.go

@@ -67,6 +67,24 @@ func TestParseConfWithChildren(t *testing.T) {
 	assert.Equal(t, 2, childStages.Len())
 }
 
+func TestParseConfWithParallel(t *testing.T) {
+	configData := ReadConfigBytes([]byte(`pipeline:
+    - name: parallel stages
+      parallel:
+          -  name: parallel command 1
+             type: command
+             command: echo "hello, world, parallel command 1"
+          -  name: parallel command 2
+             type: command
+             command: echo "hello, world, parallel command 2"`))
+	result, err := Parse(configData)
+	assert.Equal(t, 1, result.Pipeline.Size())
+	assert.Nil(t, err)
+
+	childStages := result.Pipeline.Stages.Front().Value.(stages.Stage).GetChildStages()
+	assert.Equal(t, 2, childStages.Len())
+}
+
 func TestParseConfDefaultStageTypeIsCommand(t *testing.T) {
 	configData := ReadConfigBytes([]byte(`pipeline:
     - name: command_stage_1
@@ -148,6 +166,18 @@ func TestParseConfWithInvalidChildStage(t *testing.T) {
 	assert.NotNil(t, err)
 }
 
+func TestParseConfWithInvalidParallelStage(t *testing.T) {
+	configData := ReadConfigBytes([]byte(`pipeline:
+    - name: parallel stages
+      parallel:
+          -  name: parallel command 1
+             type: xxxxx
+`))
+	result, err := Parse(configData)
+	assert.Nil(t, result)
+	assert.NotNil(t, err)
+}
+
 func TestParseConfWithServiceBlock(t *testing.T) {
 	configData := ReadConfigBytes([]byte(`
     service: