Recreate a docker container with the same configuration after an image upgrade

docker-recreate.go

package main

import (
    "fmt"
	"os"
	"strings"

    "github.com/fsouza/go-dockerclient"
	//"github.com/tonnerre/golang-pretty"
)

func check(err error) {
	if err != nil {
		fmt.Println(err)
		os.Exit(0)
	}
}

func main() {
	if len(os.Args) != 2 {
		fmt.Printf("Usage: %s [Container ID]\n", os.Args[0])
		os.Exit(0)
	}

	/*
	
		also have option to build locally, or retirieve docker file and built rather than pull
	
		Steps:
		* Pull new if from remote
		* Save old config
		* Make new container
		* Rename old
		* stop old if started
		* start new if old is running
		* option: delete old if sucsessfull
		* if error rename old to origional name, and put back in origional state

	*/

    endpoint := "unix:///var/run/docker.sock"
    client, _ := docker.NewClient(endpoint)

	// get container info
	old_container, err := client.InspectContainer(os.Args[1])
	check(err)

	//TODO delete _new if an error occores

	// pull new image
	//TODO
	// also need to ensure we use the latest version of the iamge when building?
	// TODO check to make sure rebuilt container is using updated image
	fmt.Printf("Image: %s\n", old_container.Config.Image)
	// get image data

	//TODO handle image tags/labels?

	// naming
	name := old_container.Name
	tmp_name := name+"_new"

	
	// copy container
	var options docker.CreateContainerOptions
	options.Name = tmp_name
	options.Config = old_container.Config
	options.HostConfig = old_container.HostConfig
	// get all vomumes
	//options.HostConfig.VolumesFrom = append(options.HostConfig.VolumesFrom, old_container.ID)
	options.HostConfig.VolumesFrom = []string{old_container.ID}
	
	// get all links
	// this is a hack to fix the way links are returned and sent
	links := old_container.HostConfig.Links
	for i := range links {
		parts := strings.SplitN(links[i], ":", 2)
		if len(parts) != 2 {
			fmt.Println("Unable to parse link ", links[i])
			// TODO make function and add better error return
			return
		}
		container_name := strings.TrimPrefix(parts[0], "/")
		alias_parts := strings.Split(parts[1], "/")
		alias := alias_parts[len(alias_parts)-1]
		links[i] = fmt.Sprintf("%s:%s", container_name, alias)
	}
	options.HostConfig.Links = links


	fmt.Println("Creating...")
	new_container, err := client.CreateContainer(options)
	check(err)

	// rename
	err = client.RenameContainer(docker.RenameContainerOptions{ID:old_container.ID, Name:name+"_old"})
	check(err)
	err = client.RenameContainer(docker.RenameContainerOptions{ID:new_container.ID, Name:name})
	check(err)


	if old_container.State.Running {
		fmt.Printf("Stopping old container\n")
		err = client.StopContainer(old_container.ID, 10)
		check(err)
		fmt.Printf("Starting new container\n")
		err = client.StartContainer(new_container.ID, new_container.HostConfig)
		check(err)
	}

	// add optionn to rm old container on sucsess
	fmt.Printf("Migrated from %s to %s\n", old_container.ID, new_container.ID)

	fmt.Println("Done")

}