Multi-container definition files¶

Previously when we deployed to AWS, we had a single Docker image to be ran. Now we have multiple images and we'll need to specify what exactly we need to do.

We'll need to create a Dockerrun.aws.json file, where we'll make container definitions, which is similar to docker-compose.yml file.

The Elastic Beanstalk doesn't really know on how to run containers itself, whenever it needs to do so, it delegates it to Amazon Elastic Container Service (ECS).

The Parameters on how to create the Dockerrun.aws.json file can be found here https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task_definition_parameters.html.

So, we'll create Dockerrun.aws.json file in the project directory:

{
    "AWSEBDockerrunVersion": 2,
    "containerDefinitions": [
        {
            "name": "client",
            "image": "deiveris/multi-client",
            "hostname": "client",
            "essential": false,
        },
        {
            "name": "server",
            "image": "deiveris/multi-server",
            "hostname": "api",
            "essential": false
        }, 
        {
            "name": "worker",
            "image": "deiveris/multi-worker",
            "hostname": "worker",
            "essential": false
        },
        {
            "name": "nginx",
            "image": "deiveris/multi-nginx",
            "hostname": "nginx",
            "essential": true,
            "portMappings": [
                {
                    "hostPort": 80,
                    "containerPort": 80
                }
            ],
            "links": ["client", "server"]
        }
    ]
}

The essential marks the container to be essential, meaning when it crashes - all other containers are closed down as well. At least 1 container must be marked as essential.