experimental symlink support

daemon/config.go

@@ -67,6 +67,7 @@ type Config struct {
 		EnvFile  string            `envconfig:"DRONE_RUNNER_ENVFILE"`
 		Path     string            `envconfig:"DRONE_RUNNER_PATH"`
 		Root     string            `envconfig:"DRONE_RUNNER_ROOT"`
+		Symlinks map[string]string `envconfig:"DRONE_RUNNER_SYMLINKS"`
 	}
 
 	Limit struct {

daemon/daemon.go

@@ -62,6 +62,7 @@ func Run(ctx context.Context, config Config) error {
 			Environ:  config.Runner.Environ,
 			Machine:  config.Runner.Name,
 			Root:     config.Runner.Root,
+			Symlinks: config.Runner.Symlinks,
 			Reporter: tracer,
 			Match: match.Func(
 				config.Limit.Repos,

engine/compiler/compiler.go

@@ -76,8 +76,13 @@ type Compiler struct {
 	// into the pipeline step.
 	Secret secret.Provider
 
-	// Root defines the option build root path, defaults to temp directory.
+	// Root defines the optional build root path, defaults to
+	// temp directory.
 	Root string
+
+	// Symlinks provides an optional list of symlinks that are
+	// created and linked to the pipeline workspace.
+	Symlinks map[string]string
 }
 
 // Compile compiles the configuration file.
@@ -140,6 +145,14 @@ func (c *Compiler) Compile(ctx context.Context) *engine.Spec {
 		})
 	}
 
+	// create symbolic links
+	for source, target := range c.Symlinks {
+		spec.Links = append(spec.Links, &engine.Link{
+			Source: source,
+			Target: filepath.Join(spec.Root, target),
+		})
+	}
+
 	// create the default environment variables.
 	envs := environ.Combine(
 		hostEnviron(),

engine/exec.go

@@ -58,6 +58,18 @@ func (e *engine) Setup(ctx context.Context, spec *Spec) error {
 		}
 	}
 
+	// create symlinks
+	for _, link := range spec.Links {
+		if err := os.Symlink(link.Source, link.Target); err != nil {
+			logger.FromContext(ctx).
+				WithError(err).
+				WithField("source", link.Source).
+				WithField("target", link.Target).
+				Error("cannot create symlink")
+			return err
+		}
+	}
+
 	// creates step files
 	for _, step := range spec.Steps {
 		for _, file := range step.Files {

engine/spec.go

@@ -13,6 +13,7 @@ type (
 		Platform Platform `json:"platform,omitempty"`
 		Root     string   `json:"root,omitempty"`
 		Files    []*File  `json:"files,omitempty"`
+		Links    []*Link  `json:"links,omitempty"`
 		Steps    []*Step  `json:"steps,omitempty"`
 	}
 
@@ -43,6 +44,12 @@ type (
 		IsDir bool   `json:"is_dir,omitempty"`
 	}
 
+	// Link defines a symbolic link.
+	Link struct {
+		Source string `json:"source,omitempty"`
+		Target string `json:"target,omitempty"`
+	}
+
 	// Platform defines the target platform.
 	Platform struct {
 		OS      string `json:"os,omitempty"`