dwdraju/swarm-rolling repository overview

⁠Rolling Updates of Docker Services Across Swarm Cluster

Initialize a swarm:

docker swarm init

Create docker service with 3 replica mapping internal port 80 to 8080 on host:

docker service create --name my-app --replicas 3 -p 8080:80 dwdraju/swarm-rolling:v1

Checkout localhost:8080⁠ or curl localhost:8080. You will see version 1 of the app.

Status of the service can be obtained through:

docker service inspect --pretty my-app

Expand the number of replica:

docker service update --replicas=8 my-app

Do rolling update of all of the replicas with each at once and with delay of 15 seconds:

docker service update --update-delay=15s --update-parallelism=1 --image dwdraju/swarm-rolling:v2 my-app

Now, keep on refreshing localhost:8080⁠ or curl localhost:8080 and you will see two versions randomly with later version replacing the first one gradually.

Checkout the rolling update status:

docker service inspect --pretty my-app

Limit the previous container version on history:

docker swarm update --task-history-limit 5

Check docker ps -a and you will see only latest 5 releases.