Add docker container dir to template

builder/docker/config.go

@@ -35,6 +35,7 @@ type Config struct {
 	Author       string
 	Changes      []string
 	Message      string
+	ContainerDir string `mapstructure:"container_dir"`
 
 	// This is used to login to dockerhub to pull a private base container. For
 	// pushing to dockerhub, see the docker post-processors
@@ -112,6 +113,10 @@ func NewConfig(raws ...interface{}) (*Config, []string, error) {
 		}
 	}
 
+	if c.ContainerDir == "" {
+		c.ContainerDir = "/packer-files"
+	}
+
 	if c.EcrLogin && c.LoginServer == "" {
 		errs = packer.MultiErrorAppend(errs, fmt.Errorf("ECR login requires login server to be provided."))
 	}

builder/docker/step_connect_docker.go

@@ -24,7 +24,7 @@ func (s *StepConnectDocker) Run(state multistep.StateBag) multistep.StepAction {
 	comm := &Communicator{
 		ContainerId:  containerId,
 		HostDir:      tempDir,
-		ContainerDir: "/packer-files",
+		ContainerDir: config.ContainerDir,
 		Version:      version,
 		Config:       config,
 	}

builder/docker/step_run.go

@@ -26,7 +26,7 @@ func (s *StepRun) Run(state multistep.StateBag) multistep.StepAction {
 	for host, container := range config.Volumes {
 		runConfig.Volumes[host] = container
 	}
-	runConfig.Volumes[tempDir] = "/packer-files"
+	runConfig.Volumes[tempDir] = config.ContainerDir
 
 	ui.Say("Starting docker container...")
 	containerId, err := driver.StartContainer(&runConfig)