Preparing your Docker image for deployment to Elastic Beanstalk

This section describes how to prepare your Docker image for deployment to Elastic Beanstalk with either of the Docker running AL2 or AL2023 platform branches. The configuration files that you'll require depend on whether your images are local, remote, and if you're using Docker Compose.

Note

For an example of a procedure that launches a Docker environment see the QuickStart for Docker topic.

Managing your images with Docker Compose in Elastic Beanstalk

You may choose to use Docker Compose to manage various services in one YAML file. To learn more about Docker Compose see Why use Compose? on the Docker website.

• Create a docker-compose.yml. This file is required if you're using Docker Compose to manage your application with Elastic Beanstalk. If all your deployments are sourced from images in public repositories, then no other configuration files are required. If your deployment's source images are in a private repository, you'll need to do some additional configuration. For more information, see Using images from a private repository. For more information about the docker-compose.yml file, see Compose file reference on the Docker website.

• The Dockerfile is optional. Create one if you need Elastic Beanstalk to build and run a local custom image. For more information about the Dockerfile see Dockerfile reference on the Docker website.

• You may need to create a .zip file. If you use only a Dockerfile file to deploy your application, you don't need to create one. If you use additional configuration files the .zip file must include the Dockerfile, the docker-compose.yml file, your application files, and any application file dependencies. The Dockerfile and the docker-compose.yml must be at the root, or top level, of the .zip archive. If you use the EB CLI to deploy your application, it creates a .zip file for you.

To learn more about Docker Compose and how to install it, see the Docker sites Overview of Docker Compose and Install Docker Compose.

Managing images without Docker Compose in Elastic Beanstalk

If you're not using Docker Compose to manage your Docker images, you'll need to configure a Dockerfile, a Dockerrun.aws.json file, or both.

• Create a Dockerfile to have Elastic Beanstalk build and run a custom image locally.

• Create a Dockerrun.aws.json v1 file to deploy a Docker image from a hosted repository to Elastic Beanstalk.

• You may need to create a .zip file. If you use only one of either file, the Dockerfile or the Dockerrun.aws.json, then you don't need to create a .zip file. If you use both files, then you do need a .zip file. The .zip file must include both the Dockerfile and the Dockerrun.aws.json, along with the file containing your application files plus any application file dependencies. If you use the EB CLI to deploy your application, it creates a .zip file for you.

Dockerrun.aws.json v1 configuration file

A Dockerrun.aws.json file describes how to deploy a remote Docker image as an Elastic Beanstalk application. This JSON file is specific to Elastic Beanstalk. If your application runs on an image that is available in a hosted repository, you can specify the image in a Dockerrun.aws.json v1 file and omit the Dockerfile.

Dockerrun.aws.json versions

The AWSEBDockerrunVersion parameter indicates the version of the Dockerrun.aws.json file.

• The Docker AL2 and AL2023 platforms use the following versions of the file.

  • Dockerrun.aws.json v3 — environments that use Docker Compose.

  • Dockerrun.aws.json v1 — environments that do not use Docker Compose.

• ECS running on Amazon Linux 2 and ECS running on AL2023 uses the Dockerrun.aws.json v2 file. The retired platform ECS-The Multicontainer Docker Amazon Linux AMI (AL1) also used this same version.

Dockerrun.aws.json v1

Valid keys and values for the Dockerrun.aws.json v1 file include the following operations:

AWSEBDockerrunVersion

(Required) Specify the version number 1 if you're not using Docker Compose to manage your image.

Authentication

(Required only for private repositories) Specifies the Amazon S3 object storing the .dockercfg file.

See Using images from a private repository in Elastic Beanstalk in Using images from a private repository later in this chapter.

Image

Specifies the Docker base image on an existing Docker repository from which you're building a Docker container. Specify the value of the Name key in the format <organization>/<image name> for images on Docker Hub, or <site>/<organization name>/<image name> for other sites.

When you specify an image in the Dockerrun.aws.json file, each instance in your Elastic Beanstalk environment runs docker pull to run the image. Optionally, include the Update key. The default value is true and instructs Elastic Beanstalk to check the repository, pull any updates to the image, and overwrite any cached images.

When using a Dockerfile, do not specify the Image key in the Dockerrun.aws.json file. Elastic Beanstalk always builds and uses the image described in the Dockerfile when one is present.

Ports

(Required when you specify the Image key) Lists the ports to expose on the Docker container. Elastic Beanstalk uses the ContainerPort value to connect the Docker container to the reverse proxy running on the host.

You can specify multiple container ports, but Elastic Beanstalk uses only the first port. It uses this port to connect your container to the host's reverse proxy and route requests from the public internet. If you're using a Dockerfile, the first ContainerPort value should match the first entry in the Dockerfile's EXPOSE list.

Optionally, you can specify a list of ports in HostPort. HostPort entries specify the host ports that ContainerPort values are mapped to. If you don't specify a HostPort value, it defaults to the ContainerPort value.

{
  "Image": {
    "Name": "image-name"
  },
  "Ports": [
    {
      "ContainerPort": 8080,
      "HostPort": 8000
    }
  ]
}
          

Volumes

Map volumes from an EC2 instance to your Docker container. Specify one or more arrays of volumes to map.

{
  "Volumes": [
    {
      "HostDirectory": "/path/inside/host",
      "ContainerDirectory": "/path/inside/container"
    }
  ]
...

Logging

Specify the directory inside the container to which your application writes logs. Elastic Beanstalk uploads any logs in this directory to Amazon S3 when you request tail or bundle logs. If you rotate logs to a folder named rotated within this directory, you can also configure Elastic Beanstalk to upload rotated logs to Amazon S3 for permanent storage. For more information, see Viewing logs from Amazon EC2 instances in your Elastic Beanstalk environment.

Command

Specify a command to run in the container. If you specify an Entrypoint, then Command is added as an argument to Entrypoint. For more information, see CMD in the Docker documentation.

Entrypoint

Specify a default command to run when the container starts. For more information, see ENTRYPOINT in the Docker documentation.

The following snippet is an example that illustrates the syntax of the Dockerrun.aws.json file for a single container.

{
  "AWSEBDockerrunVersion": "1",
  "Image": {
    "Name": "janedoe/image",
    "Update": "true"
  },
  "Ports": [
    {
      "ContainerPort": "1234"
    }
  ],
  "Volumes": [
    {
      "HostDirectory": "/var/app/mydb",
      "ContainerDirectory": "/etc/mysql"
    }
  ],
  "Logging": "/var/log/nginx",
  "Entrypoint": "/app/bin/myapp",
  "Command": "--argument"
}>

You can provide Elastic Beanstalk with only the Dockerrun.aws.json file, or with a .zip archive containing both the Dockerrun.aws.json and Dockerfile files. When you provide both files, the Dockerfile describes the Docker image and the Dockerrun.aws.json file provides additional information for deployment, as described later in this section.

Note

The two files must be at the root, or top level, of the .zip archive. Don't build the archive from a directory containing the files. Instead, navigate into that directory and build the archive there.

When you provide both files, don't specify an image in the Dockerrun.aws.json file. Elastic Beanstalk builds and uses the image described in the Dockerfile and ignores the image specified in the Dockerrun.aws.json file.

Building custom images with a Dockerfile

You need to create a Dockerfile if you don't already have an existing image hosted in a repository.

The following snippet is an example of the Dockerfile. If you follow the instructions in QuickStart for Docker, you can upload this Dockerfile as written. Elastic Beanstalk runs the game 2048 when you use this Dockerfile.

For more information about instructions you can include in the Dockerfile, see Dockerfile reference on the Docker website.

FROM ubuntu:12.04

RUN apt-get update
RUN apt-get install -y nginx zip curl

RUN echo "daemon off;" >> /etc/nginx/nginx.conf
RUN curl -o /usr/share/nginx/www/master.zip -L https://codeload.github.com/gabrielecirulli/2048/zip/master
RUN cd /usr/share/nginx/www/ && unzip master.zip && mv 2048-master/* . && rm -rf 2048-master master.zip

EXPOSE 80

CMD ["/usr/sbin/nginx", "-c", "/etc/nginx/nginx.conf"]

Note

You can run multi-stage builds from a single Dockerfile to produce smaller-sized images with a significant reduction in complexity. For more information, see Use multi-stage builds on the Docker documentation website.