Docker for AWS swarm auto login to AWS ECR registry

-- Using AWS ECR with a Docker Swarm stack on AWS

When creating a docker swarm stack on AWS, you can want to use the AWS ECR service as your docker images registry.

The problem

The ECR authentication tokens are only valid for 12 hours, so the docker swarm services won't be able to scale on another node after the expire date.

The solution

This docker image renews the ECR token each 4h and update all the services using an ECR image.

Usage as a swarm service (recommended)

docker service create \
    --name aws_ecr_auth \
    --mount type=bind,source=/var/run/docker.sock,destination=/var/run/docker.sock \
    --constraint 'node.role == manager' \
    --restart-condition 'none' \
    --detach=false \
    mroca/swarm-aws-ecr-auth

Usage as a swarm container

docker run --rm -v /var/run/docker.sock:/var/run/docker.sock --name aws_ecr_auth mroca/swarm-aws-ecr-auth

Configuration

By default, this image authenticates the swarm manager onto the AWS ECR for the current region. You can configure the ECR region by setting the AWS_REGION env variable : -e AWS_REGION=eu-west-3, for example.

Requirements

The swarm stack must have been created with the https://docs.docker.com/docker-for-aws/ CloudFormation template.
The swarm managers must have the AmazonEC2ContainerRegistryReadOnly policy.
The services must have been created with --with-registry-auth option.