Option to change temp dir for local backend (#2702)

---
*Sponsored by Kithara Software GmbH*

docs/docs/30-administration/15-agent-config.md

@@ -188,6 +188,10 @@ See [Docker backend configuration](./22-backends/10-docker.md#configuration)
 
 See [Kubernetes backend configuration](./22-backends/40-kubernetes.md#configuration)
 
+### `WOODPECKER_BACKEND_LOCAL_*`
+
+See [Local backend configuration](./22-backends/20-local.md#further-configuration)
+
 ## Advanced Settings
 
 :::warning

docs/docs/30-administration/22-backends/20-local.md

@@ -123,3 +123,12 @@ labels:
 
 steps: [...]
 ```
+
+### Change temp directory
+
+We use the default temp directory to create folders for workflows.
+This directory can be changed by:
+
+```env
+WOODPECKER_BACKEND_LOCAL_TEMP_DIR=/some/other/dir
+```

pipeline/backend/local/command.go

@@ -22,7 +22,7 @@ import (
 	"github.com/alessio/shellescape"
 )
 
-func genCmdByShell(shell string, cmds []string) (args []string, err error) {
+func (e *local) genCmdByShell(shell string, cmds []string) (args []string, err error) {
 	script := ""
 	for _, cmd := range cmds {
 		script += fmt.Sprintf("echo %s\n%s\n", strings.TrimSpace(shellescape.Quote("+ "+cmd)), cmd)
@@ -37,7 +37,7 @@ func genCmdByShell(shell string, cmds []string) (args []string, err error) {
 			script += fmt.Sprintf("@%s\n", cmd)
 			script += "@IF NOT %ERRORLEVEL% == 0 exit %ERRORLEVEL%\n"
 		}
-		cmd, err := os.CreateTemp(os.TempDir(), "*.cmd")
+		cmd, err := os.CreateTemp(e.tempDir, "*.cmd")
 		if err != nil {
 			return nil, err
 		}

pipeline/backend/local/flags.go

@@ -15,7 +15,16 @@
 package local
 
 import (
+	"os"
+
 	"github.com/urfave/cli/v2"
 )
 
-var Flags = []cli.Flag{}
+var Flags = []cli.Flag{
+	&cli.StringFlag{
+		Name:    "backend-local-temp-dir",
+		EnvVars: []string{"WOODPECKER_BACKEND_LOCAL_TEMP_DIR"},
+		Usage:   "set a different temp dir to clone workflows into",
+		Value:   os.TempDir(),
+	},
+}

pipeline/backend/local/local.go

@@ -27,6 +27,7 @@ import (
 	"sync"
 
 	"github.com/rs/zerolog/log"
+	"github.com/urfave/cli/v2"
 	"golang.org/x/text/encoding/unicode"
 	"golang.org/x/text/transform"
 
@@ -42,6 +43,7 @@ type workflowState struct {
 }
 
 type local struct {
+	tempDir         string
 	workflows       sync.Map
 	output          io.ReadCloser
 	pluginGitBinary string
@@ -64,7 +66,12 @@ func (e *local) IsAvailable(context.Context) bool {
 	return true
 }
 
-func (e *local) Load(context.Context) (*types.EngineInfo, error) {
+func (e *local) Load(ctx context.Context) (*types.EngineInfo, error) {
+	c, ok := ctx.Value(types.CliContext).(*cli.Context)
+	if ok {
+		e.tempDir = c.String("backend-local-temp-dir")
+	}
+
 	e.loadClone()
 
 	return &types.EngineInfo{
@@ -76,7 +83,7 @@ func (e *local) Load(context.Context) (*types.EngineInfo, error) {
 func (e *local) SetupWorkflow(_ context.Context, _ *types.Config, taskUUID string) error {
 	log.Trace().Str("taskUUID", taskUUID).Msg("create workflow environment")
 
-	baseDir, err := os.MkdirTemp("", "woodpecker-local-*")
+	baseDir, err := os.MkdirTemp(e.tempDir, "woodpecker-local-*")
 	if err != nil {
 		return err
 	}
@@ -139,7 +146,7 @@ func (e *local) StartStep(ctx context.Context, step *types.Step, taskUUID string
 // execCommands use step.Image as shell and run the commands in it
 func (e *local) execCommands(ctx context.Context, step *types.Step, state *workflowState, env []string) error {
 	// Prepare commands
-	args, err := genCmdByShell(step.Image, step.Commands)
+	args, err := e.genCmdByShell(step.Image, step.Commands)
 	if err != nil {
 		return fmt.Errorf("could not convert commands into args: %w", err)
 	}