fix(host): correct host workspace cleanup on Windows (#883)

## Summary
- Fix host-mode cleanup to remove the job **workspace** directory after a run (instead of leaving checkouts behind).
- On Windows, track step process PIDs and terminate remaining process trees during teardown before attempting workspace deletion (prevents file-lock failures).
- Skip workspace deletion when `bind_workdir` is enabled to avoid conflicting with runner-level task directory cleanup.

## Implementation details
- `HostEnvironment` now records PIDs for started commands and best-effort terminates them on Windows during `Remove()`.
- Workspace removal uses a small retry loop on Windows to handle transient locks.
- `BindWorkdir` is propagated into `HostEnvironment` so cleanup behavior matches runner configuration.

---------

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: silverwind <2021+silverwind@noreply.gitea.com>
Reviewed-on: https://gitea.com/gitea/runner/pulls/883
Reviewed-by: silverwind <2021+silverwind@noreply.gitea.com>

act/container/host_environment.go

@@ -16,7 +16,9 @@ import (
 	"os/exec"
 	"path/filepath"
 	"runtime"
+	"strconv"
 	"strings"
+	"sync"
 	"time"
 
 	"gitea.com/gitea/runner/act/common"
@@ -34,9 +36,15 @@ type HostEnvironment struct {
 	TmpDir    string
 	ToolCache string
 	Workdir   string
+	// BindWorkdir is true when the app runner mounts the workspace on the host and
+	// deletes the task directory after the job; host teardown must not remove Workdir.
+	BindWorkdir bool
 	ActPath     string
 	CleanUp     func()
 	StdOut      io.Writer
+
+	mu          sync.Mutex
+	runningPIDs map[int]struct{}
 }
 
 func (e *HostEnvironment) Create(_, _ []string) common.Executor {
@@ -344,7 +352,25 @@ func (e *HostEnvironment) exec(ctx context.Context, command []string, cmdline st
 	if ppty != nil {
 		go writeKeepAlive(ppty)
 	}
-	err = cmd.Run()
+	// Split Start/Wait so the PID can be registered before the process can exit;
+	// cmd.Run() would block until exit, by which time the PID may have been reused.
+	if err := cmd.Start(); err != nil {
+		return err
+	}
+	if cmd.Process != nil {
+		e.mu.Lock()
+		if e.runningPIDs == nil {
+			e.runningPIDs = map[int]struct{}{}
+		}
+		e.runningPIDs[cmd.Process.Pid] = struct{}{}
+		e.mu.Unlock()
+		defer func(pid int) {
+			e.mu.Lock()
+			delete(e.runningPIDs, pid)
+			e.mu.Unlock()
+		}(cmd.Process.Pid)
+	}
+	err = cmd.Wait()
 	if err != nil {
 		return err
 	}
@@ -385,12 +411,83 @@ func (e *HostEnvironment) UpdateFromEnv(srcPath string, env *map[string]string)
 	return parseEnvFile(e, srcPath, env)
 }
 
+func removePathWithRetry(ctx context.Context, path string) error {
+	if path == "" {
+		return nil
+	}
+	attempts := 1
+	delay := time.Duration(0)
+	if runtime.GOOS == "windows" {
+		attempts = 5
+		delay = 200 * time.Millisecond
+	}
+	var lastErr error
+	for i := 0; i < attempts; i++ {
+		if i > 0 {
+			select {
+			case <-ctx.Done():
+				return ctx.Err()
+			case <-time.After(delay):
+			}
+		}
+		lastErr = os.RemoveAll(path)
+		if lastErr == nil {
+			return nil
+		}
+	}
+	return lastErr
+}
+
+func (e *HostEnvironment) terminateRunningProcesses(ctx context.Context) {
+	if runtime.GOOS != "windows" {
+		return
+	}
+	e.mu.Lock()
+	pids := make([]int, 0, len(e.runningPIDs))
+	for pid := range e.runningPIDs {
+		pids = append(pids, pid)
+	}
+	e.mu.Unlock()
+
+	if len(pids) == 0 {
+		return
+	}
+
+	logger := common.Logger(ctx)
+	for _, pid := range pids {
+		// Best-effort: forcibly terminate process tree to release file handles
+		// so that workspace cleanup can succeed on Windows.
+		cmd := exec.CommandContext(ctx, "taskkill", "/PID", strconv.Itoa(pid), "/T", "/F")
+		out, err := cmd.CombinedOutput()
+		if err != nil {
+			logger.Debugf("taskkill failed for pid=%d: %v output=%s", pid, err, strings.TrimSpace(string(out)))
+		}
+	}
+}
+
 func (e *HostEnvironment) Remove() common.Executor {
 	return func(ctx context.Context) error {
+		// Ensure any lingering child processes are ended before attempting
+		// to remove the workspace (Windows file locks otherwise prevent cleanup).
+		e.terminateRunningProcesses(ctx)
+
+		// Only removes per-job misc state. Must not remove the cache/toolcache root.
 		if e.CleanUp != nil {
 			e.CleanUp()
 		}
-		return os.RemoveAll(e.Path)
+		logger := common.Logger(ctx)
+		var errs []error
+		if err := removePathWithRetry(ctx, e.Path); err != nil {
+			logger.Warnf("failed to remove host misc state %s: %v", e.Path, err)
+			errs = append(errs, err)
+		}
+		if !e.BindWorkdir && e.Workdir != "" {
+			if err := removePathWithRetry(ctx, e.Workdir); err != nil {
+				logger.Warnf("failed to remove host workspace %s: %v", e.Workdir, err)
+				errs = append(errs, err)
+			}
+		}
+		return errors.Join(errs...)
 	}
 }
 

act/container/host_environment_test.go

@@ -13,7 +13,11 @@ import (
 	"path/filepath"
 	"testing"
 
+	"gitea.com/gitea/runner/act/common"
+
+	"github.com/sirupsen/logrus"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 // Type assert HostEnvironment implements ExecutionsEnvironment
@@ -69,3 +73,51 @@ func TestGetContainerArchive(t *testing.T) {
 	_, err = reader.Next()
 	assert.ErrorIs(t, err, io.EOF)
 }
+
+func TestHostEnvironmentRemoveCleansWorkdir(t *testing.T) {
+	logger := logrus.New()
+	ctx := common.WithLogger(context.Background(), logrus.NewEntry(logger))
+	base := t.TempDir()
+	miscRoot := filepath.Join(base, "misc")
+	path := filepath.Join(miscRoot, "hostexecutor")
+	require.NoError(t, os.MkdirAll(path, 0o700))
+	workdir := filepath.Join(base, "workspace", "owner", "repo")
+	require.NoError(t, os.MkdirAll(workdir, 0o700))
+
+	e := &HostEnvironment{
+		Path:        path,
+		Workdir:     workdir,
+		BindWorkdir: false,
+		CleanUp: func() {
+			_ = os.RemoveAll(miscRoot)
+		},
+		StdOut: os.Stdout,
+	}
+	require.NoError(t, e.Remove()(ctx))
+	_, err := os.Stat(workdir)
+	assert.ErrorIs(t, err, os.ErrNotExist)
+}
+
+func TestHostEnvironmentRemoveSkipsWorkdirWhenBindWorkdir(t *testing.T) {
+	logger := logrus.New()
+	ctx := common.WithLogger(context.Background(), logrus.NewEntry(logger))
+	base := t.TempDir()
+	miscRoot := filepath.Join(base, "misc")
+	path := filepath.Join(miscRoot, "hostexecutor")
+	require.NoError(t, os.MkdirAll(path, 0o700))
+	workdir := filepath.Join(base, "workspace", "123", "owner", "repo")
+	require.NoError(t, os.MkdirAll(workdir, 0o700))
+
+	e := &HostEnvironment{
+		Path:        path,
+		Workdir:     workdir,
+		BindWorkdir: true,
+		CleanUp: func() {
+			_ = os.RemoveAll(miscRoot)
+		},
+		StdOut: os.Stdout,
+	}
+	require.NoError(t, e.Remove()(ctx))
+	_, err := os.Stat(workdir)
+	require.NoError(t, err)
+}

act/runner/run_context.go

@@ -224,6 +224,7 @@ func (rc *RunContext) startHostEnvironment() common.Executor {
 			TmpDir:      runnerTmp,
 			ToolCache:   toolCache,
 			Workdir:     rc.Config.Workdir,
+			BindWorkdir: rc.Config.BindWorkdir,
 			ActPath:     actPath,
 			CleanUp: func() {
 				os.RemoveAll(miscpath)

internal/app/run/runner.go

@@ -12,6 +12,7 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"runtime"
 	"strings"
 	"sync"
 	"sync/atomic"
@@ -238,6 +239,13 @@ func (r *Runner) run(ctx context.Context, task *runnerv1.Task, reporter *report.
 		workdirParent = fmt.Sprintf("%s/%d", workdirParent, task.Id)
 	}
 	workdir := filepath.FromSlash(fmt.Sprintf("/%s/%s", workdirParent, preset.Repository))
+	if runtime.GOOS == "windows" {
+		if abs, err := filepath.Abs(workdir); err == nil {
+			workdir = abs
+		}
+	}
+	// Without bind_workdir, the workspace path omits the task id; concurrent host-mode jobs
+	// for the same repository would share this directory and can race with per-job cleanup.
 
 	runnerConfig := &runner.Config{
 		// On Linux, Workdir will be like "/<parent_directory>/<owner>/<repo>"