feat: add ability to set watch: true in Taskfile (#1361)

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Add ability to set `watch: true` in a task to automatically run it in watch
+  mode (#231, #1361 by @andreynering).
 - Fixed a nil pointer error when running a Taskfile with no contents (#1341,
   #1342 by @pd93).
 - Added a new [exit code](https://taskfile.dev/api/#exit-codes) (107) for when a

docs/docs/usage.md

@@ -1806,6 +1806,31 @@ The default watch interval is 5 seconds, but it's possible to change it by
 either setting `interval: '500ms'` in the root of the Taskfile passing it as an
 argument like `--interval=500ms`.
 
+Also, it's possible to set `watch: true` in a given task and it'll automatically
+run in watch mode:
+
+```yaml
+version: '3'
+
+interval: 500ms
+
+tasks:
+  build:
+    desc: Builds the Go application
+    sources:
+      - '**/*.go'
+    cmds:
+      - go build  # ...
+```
+
+:::info
+
+Note that when setting `watch: true` to a task, it'll only run in watch mode
+when running from the CLI via `task my-watch-task`, but won't run in watch mode
+if called by another task, either directly or as a dependency.
+
+:::
+
 <!-- prettier-ignore-start -->
 [gotemplate]: https://golang.org/pkg/text/template/
 <!-- prettier-ignore-end -->

docs/static/schema.json

@@ -188,6 +188,11 @@
           "requires": {
             "description": "A list of variables which should be set if this task is to run, if any of these variables are unset the task will error and not run",
             "$ref": "#/definitions/3/requires_obj"
+          },
+          "watch": {
+            "description": "Configures a task to run in watch mode automatically.",
+            "type": "boolean",
+            "default": false
           }
         }
       },

task.go

@@ -123,12 +123,13 @@ func (e *Executor) Run(ctx context.Context, calls ...taskfile.Call) error {
 		return nil
 	}
 
-	if e.Watch {
-		return e.watchTasks(calls...)
+	regularCalls, watchCalls, err := e.splitRegularAndWatchCalls(calls...)
+	if err != nil {
+		return err
 	}
 
 	g, ctx := errgroup.WithContext(ctx)
-	for _, c := range calls {
+	for _, c := range regularCalls {
 		c := c
 		if e.Parallel {
 			g.Go(func() error { return e.RunTask(ctx, c) })
@@ -138,7 +139,31 @@ func (e *Executor) Run(ctx context.Context, calls ...taskfile.Call) error {
 			}
 		}
 	}
-	return g.Wait()
+	if err := g.Wait(); err != nil {
+		return err
+	}
+
+	if len(watchCalls) > 0 {
+		return e.watchTasks(watchCalls...)
+	}
+
+	return nil
+}
+
+func (e *Executor) splitRegularAndWatchCalls(calls ...taskfile.Call) (regularCalls []taskfile.Call, watchCalls []taskfile.Call, err error) {
+	for _, c := range calls {
+		t, err := e.GetTask(c)
+		if err != nil {
+			return nil, nil, err
+		}
+
+		if e.Watch || t.Watch {
+			watchCalls = append(watchCalls, c)
+		} else {
+			regularCalls = append(regularCalls, c)
+		}
+	}
+	return
 }
 
 // RunTask runs a task by its name

taskfile/task.go

@@ -41,6 +41,7 @@ type Task struct {
 	IncludedTaskfile     *IncludedTaskfile
 	Platforms            []*Platform
 	Location             *Location
+	Watch                bool
 }
 
 func (t *Task) Name() string {
@@ -101,6 +102,7 @@ func (t *Task) UnmarshalYAML(node *yaml.Node) error {
 			Run           string
 			Platforms     []*Platform
 			Requires      *Requires
+			Watch         bool
 		}
 		if err := node.Decode(&task); err != nil {
 			return err
@@ -138,6 +140,7 @@ func (t *Task) UnmarshalYAML(node *yaml.Node) error {
 		t.Run = task.Run
 		t.Platforms = task.Platforms
 		t.Requires = task.Requires
+		t.Watch = task.Watch
 		return nil
 	}
 

variables.go

@@ -70,6 +70,7 @@ func (e *Executor) compiledTask(call taskfile.Call, evaluateShVars bool) (*taskf
 		Platforms:            origTask.Platforms,
 		Location:             origTask.Location,
 		Requires:             origTask.Requires,
+		Watch:                origTask.Watch,
 	}
 	new.Dir, err = execext.Expand(new.Dir)
 	if err != nil {