Swarm rescheduling

You are viewing docs for legacy standalone Swarm. These topics describe standalone Docker Swarm. In Docker 1.12 and higher, Swarm mode is integrated with Docker Engine. Most users should use integrated Swarm mode — a good place to start is Getting started with swarm mode, Swarm mode CLI commands, and the Get started with Docker walkthrough). Standalone Docker Swarm is not integrated into the Docker Engine API and CLI commands.

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You can set rescheduling policies with Docker Swarm. A rescheduling policy determines what the Swarm scheduler does for containers when the nodes they are running on fail.

Rescheduling policies

You set the reschedule policy when you start a container. You can do this with the reschedule environment variable or the com.docker.swarm.reschedule-policies label. If you don’t specify a policy, the default rescheduling policy is off which means that Swarm does not restart a container when a node fails.

To set the on-node-failure policy with a reschedule environment variable:

$ docker run -d -e "reschedule:on-node-failure" redis

To set the same policy with a com.docker.swarm.reschedule-policies label:

$ docker run -d -l 'com.docker.swarm.reschedule-policies=["on-node-failure"]' redis

Review reschedule logs

You can use the docker logs command to review the rescheduled container actions. To do this, use the following command syntax:

docker logs SWARM_MANAGER_CONTAINER_ID

When a container is successfully rescheduled, it generates a message similar to the following:

Rescheduled container 2536adb23 from node-1 to node-2 as 2362901cb213da321
Container 2536adb23 was running, starting container 2362901cb213da321

If for some reason, the new container fails to start on the new node, the log contains:

Failed to start rescheduled container 2362901cb213da321
docker, swarm, clustering, rescheduling