How to rebuild and update a container without down

Question

I enjoy a lot using docker-compose.

Eg. on my server, when I want to update my app with minor changes, I only need to git pull origin master && docker-compose restart, works perfectly.

But sometimes, I need to rebuild (eg. I added an npm dependency, need to run npm install again).

In this case, I do docker-compose build --no-cache && docker-compose restart.

I would expect this to :

• create a new instance of my container
• stop the existing container (after the newer has finished building)
• start the new one
• optionally remove the old one, but this could be done manually

But in practice it seems to restart the former one again.

Is it the expected behavior?

How can I handle a rebuild and start the new one after it is built?

Maybe I missed a specific command? Or would it make sense to have it?

Answer 1

Though the accepted answer shall work to rebuild the container before starting the new one as a replacement, it is ok for simple use case, but the container will still be down during new container initialization process. If this is quite long, it can be an issue.

I managed to achieve rolling updates with docker-compose (along with a nginx reverse proxy), and detailed how I built that in this github issue: https://github.com/docker/compose/issues/1786#issuecomment-579794865

Hope it can help!

Answer 2

Use the --build flag to the up command, along with the -d flag to run your containers in the background:

docker-compose up -d --build

This will rebuild all images defined in your compose file, then restart any containers whose images have changed.

-d assumes that you don't want to keep everything running in your shell foreground. This makes it act more like restart, but it's not required.

Answer 3

Don't manage your application environment directly. Use deployment tool like Rancher / Kubernetes. Using one you will be able to upgrade your dockerized application without any downtime and even downgrade it should you need to.

Running Rancher is as easy as running another docker container as this tool is available in the Docker Hub.

Answer 4

from the manual docker-compose restart

If you make changes to your docker-compose.yml configuration these changes will not be reflected after running this command.

you should be able to do

$docker-compose up -d --no-deps --build <service_name>

The --no-deps will not start linked services.

Answer 5

The problem is that restart will restart your current containers, which is not what you want.

As an example, I just did this

• change the docker file for one of the images
• call docker-compose build to build the images
• call docker-compose down¹ and docker-compose up
  • docker-compose restart will NOT work here
  • using docker-compose start instead also does not work

To be honest, i'm not completly sure you need to do a down first, but that should be easy to check.¹ The bottomline is that you need to call up. You will see the containers of unchanged images restarting, but for the changed image you'll see recreating.

The advantage of this over just calling up --build is that you can see the building-process first before you restart.

1: from the comments; down is not needed, you can just call up --build. Down has some "down"-sides, including possible being destructive to your (volume-)data.

Answer 6

You can use Swarm. Init swarm first by docker swarm init command and use healthcheck in docker-compose.yml.

Then run below command:

docker stack deploy -c docker-compose.yml project_name

instead of

docker-compose up -d.

When docker-compose.yml file is updated only run this command again:

docker stack deploy -c docker-compose.yml project_name

Docker Swarm will create new version of services and stop old version after that.