Add CHANGELOG, documentation and small improvements to #626

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## Unreleased
 
+- It's now possible to schedule cleanup commands to run once a task finishes
+  with the `defer:` keyword
+  ([Documentation](https://taskfile.dev/#/usage?id=doing-task-cleanup-with-defer), [#475](https://github.com/go-task/task/issues/475), [#626](https://github.com/go-task/task/pull/626/files)).
 - Remove long deprecated and undocumented `$` variable prefix and `^` command
   prefix
   ([#642](https://github.com/go-task/task/issues/642), [#644](https://github.com/go-task/task/issues/644), [#645](https://github.com/go-task/task/pull/645)).

docs/usage.md

@@ -608,6 +608,45 @@ tasks:
       - yarn {{.CLI_ARGS}}
 ```
 
+## Doing task cleanup with `defer`
+
+With the `defer` keyword, it's possible to schedule cleanup to be run once
+the task finishes. The difference with just putting it as the last command is
+that this command will run even when the task fails.
+
+In the example below `rm -rf tmpdir/` will run even if the third command fails:
+
+```yaml
+version: '3'
+
+tasks:
+  default:
+    cmds:
+      - mkdir -p tmpdir/
+      - defer: rm -rf tmpdir/
+      - echo 'Do work on tmpdir/'
+```
+
+If you want to move the cleanup command into another task, that's possible as
+well:
+
+```yaml
+version: '3'
+
+tasks:
+  default:
+    cmds:
+      - mkdir -p tmpdir/
+      - defer: { task: cleanup }
+      - echo 'Do work on tmpdir/'
+
+  cleanup: rm -rf tmpdir/
+```
+
+> NOTE: Due to the nature of how the
+[Go's own `defer` work](https://go.dev/tour/flowcontrol/13), the deferred
+commands are executed in the reverse order if you schedule multiple of them.
+
 ## Go's template engine
 
 Task parse commands as [Go's template engine][gotemplate] before executing

task.go

@@ -8,7 +8,6 @@ import (
 	"os"
 	"sync"
 	"sync/atomic"
-	"time"
 
 	"github.com/go-task/task/v3/internal/compiler"
 	compilerv2 "github.com/go-task/task/v3/internal/compiler/v2"
@@ -402,8 +401,9 @@ func (e *Executor) runDeps(ctx context.Context, t *taskfile.Task) error {
 }
 
 func (e *Executor) runDeferred(t *taskfile.Task, call taskfile.Call, i int) {
-	ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
+	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
+
 	if err := e.runCommand(ctx, t, call, i); err != nil {
 		e.Logger.VerboseErrf(logger.Yellow, `task: ignored error in deferred cmd: %s`, err.Error())
 	}

taskfile/cmd.go

@@ -43,10 +43,7 @@ func (c *Cmd) UnmarshalYAML(unmarshal func(interface{}) error) error {
 		return nil
 	}
 	var deferredCall struct {
-		Defer struct {
-			Task string
-			Vars *Vars
-		}
+		Defer Call
 	}
 	if err := unmarshal(&deferredCall); err == nil && deferredCall.Defer.Task != "" {
 		c.Defer = true