code: func makeMountPaths(opts *types.DeployOptions) ([]string, map[string]struct{}) {
  	binds := []string{}
  	volumes := make(map[string]struct{})
  
  	var expandENV = func(env string) string {
  		envMap := map[string]string{}
  		for _, env := range opts.Env {
  			parts := strings.Split(env, "=")
  			envMap[parts[0]] = parts[1]
  		}
  		return envMap[env]
  	}
  
  	for _, path := range opts.Volumes {
  		expanded := os.Expand(path, expandENV)
  		parts := strings.Split(expanded, ":")
  		if len(parts) == 2 {
  			binds = append(binds, fmt.Sprintf("%s:%s:rw", parts[0], parts[1]))
  			volumes[parts[1]] = struct{}{}
  		} else if len(parts) == 3 {
  			binds = append(binds, fmt.Sprintf("%s:%s:%s", parts[0], parts[1], parts[2]))
  			volumes[parts[1]] = struct{}{}
  		}
  	}
  
  	return binds, volumes
  }
docs: // make mount paths
  // volumes:
  //     - "/foo-data:$SOMEENV/foodata:rw"