Various Ways of Restarting Docker Containers

When running docker containers, it’s important to be aware that both the container and server can crash at any time. When either of these events occur, containers are not automatically brought back up.

If running Docker on a single host, the –restart flag can be passed in as an option to the docker run command.

docker run --restart=always image

This should cause the container to restart when a crash happens.

If running docker in a swarm cluster, there is a new experimental feature in Docker Swarm 1.1 that will rebalance containers. The current way of doing this is to pass an environment variable to the docker run command.

docker run -e reschedule:on-node-failure image

However, at the time of writing, this is still experimental and so docker swarm must be run in experimental mode.

docker run swarm -experimental manage

docker run swarm -experimental join

Alternatives to using the built in Docker / Swarm restart features include process managers like systemd, upstart, or supervisor. These are useful if non docker processes are dependent on docker containers, and/or you want to take advantage of process manager features that handle dependencies.

The stack uses CoreOS on DigitalOcean and so systemd is used to restart containers. The current systemd file can be found on GitHub

Brandon Chothia

Debonair Developer