Add parent directory for working directory (#154)

Fixes #145

At present, the working directory of a work flow is a path like `/<owner>/<repo>`, so the directory may conflict with system directory like `/usr/bin`. We need to add a parent directory for the working directory.
In this PR, the parent directory is `/workspace` by default and users could configure it by the `workdir_parent` option.

This change doesn't affect the host mode because in host mode the working directory will always be in `$HOME/.cache/act/` directory.

Co-authored-by: Jason Song <i@wolfogre.com>
Reviewed-on: https://gitea.com/gitea/act_runner/pulls/154
Reviewed-by: Jason Song <i@wolfogre.com>
Co-authored-by: Zettat123 <zettat123@gmail.com>
Co-committed-by: Zettat123 <zettat123@gmail.com>

internal/app/run/runner.go

@@ -166,9 +166,9 @@ func (r *Runner) run(ctx context.Context, task *runnerv1.Task, reporter *report.
 	}
 
 	runnerConfig := &runner.Config{
-		// On Linux, Workdir will be like "/<owner>/<repo>"
-		// On Windows, Workdir will be like "\<owner>\<repo>"
-		Workdir:     filepath.FromSlash(string(filepath.Separator) + preset.Repository),
+		// On Linux, Workdir will be like "/<parent_directory>/<owner>/<repo>"
+		// On Windows, Workdir will be like "\<parent_directory>\<owner>\<repo>"
+		Workdir:     filepath.FromSlash(fmt.Sprintf("/%s/%s", r.cfg.Container.WorkdirParent, preset.Repository)),
 		BindWorkdir: false,
 
 		ReuseContainers:       false,

internal/pkg/config/config.example.yaml

@@ -48,3 +48,6 @@ container:
   privileged: false
   # And other options to be used when the container is started (eg, --add-host=my.gitea.url:host-gateway).
   options:
+  # The parent directory of a job's working directory.
+  # If it's empty, /workspace will be used.
+  workdir_parent:

internal/pkg/config/config.go

@@ -34,9 +34,10 @@ type Config struct {
 		Port    uint16 `yaml:"port"`
 	} `yaml:"cache"`
 	Container struct {
-		NetworkMode string `yaml:"network_mode"`
-		Privileged  bool   `yaml:"privileged"`
-		Options     string `yaml:"options"`
+		NetworkMode   string `yaml:"network_mode"`
+		Privileged    bool   `yaml:"privileged"`
+		Options       string `yaml:"options"`
+		WorkdirParent string `yaml:"workdir_parent"`
 	} `yaml:"container"`
 }
 
@@ -94,6 +95,9 @@ func LoadDefault(file string) (*Config, error) {
 	if cfg.Container.NetworkMode == "" {
 		cfg.Container.NetworkMode = "bridge"
 	}
+	if cfg.Container.WorkdirParent == "" {
+		cfg.Container.WorkdirParent = "workspace"
+	}
 	if cfg.Runner.FetchTimeout <= 0 {
 		cfg.Runner.FetchTimeout = 5 * time.Second
 	}