Configuring Elastic Beanstalk Docker environments

This chapter explains additional configuration information for all of the supported Docker platform branches, including the ECS managed Docker platform branch. Unless a specific platform branch or platform branch component is identified in a section, it applies to all environments that are running supported Docker and ECS manged Docker platforms.

Note

If your Elastic Beanstalk environment uses an Amazon Linux AMI Docker platform version (preceding Amazon Linux 2), be sure to read the additional information in Docker configuration on Amazon Linux AMI (preceding Amazon Linux 2).

Configuring software in Docker environments

You can use the Elastic Beanstalk console to configure the software running on your environment's instances.

To configure your Docker environment in the Elastic Beanstalk console

1. Open the Elastic Beanstalk console, and in the Regions list, select your AWS Region.

2. In the navigation pane, choose Environments, and then choose the name of your environment from the list.

   Note

   If you have many environments, use the search bar to filter the environment list.

3. In the navigation pane, choose Configuration.

4. In the Updates, monitoring, and logging configuration category, choose Edit.

5. Make necessary configuration changes.

6. To save the changes choose Apply at the bottom of the page.

For information about configuring software settings in any environment, see Environment variables and other software settings. The following sections cover Docker specific information.

Container options

The Container options section has platform-specific options. For Docker environments, it lets you choose whether or not your environment includes the NGINX proxy server.

Environments with Docker Compose

If you manage your Docker environment with Docker Compose, Elastic Beanstalk assumes that you run a proxy server as a container. Therefore it defaults to None for the Proxy server setting, and Elastic Beanstalk does not provide an NGINX configuration.

Note

Even if you select NGINX as a proxy server, this setting is ignored in an environment with Docker Compose. The Proxy server setting still defaults to None.

Since the NGINX web server proxy is disabled for the Docker on Amazon Linux 2 platform with Docker Compose, you must follow the instructions for generating logs for enhanced health reporting. For more information, see Generating logs for enhanced health reporting with Docker Compose.

Environment properties (environment variables)

You can use environment properties, (also known as environment variables), to pass values, such endpoints, debug settings, and other information to your application. The Environment variables section of the console lets you specify environment variables on the EC2 instances that are running your application. Environment variables are passed in as key-value pairs to the application.

Your application code running in a container can refer to an environment variable by name and read its value. The source code that reads these environment variables will vary by programming language. You can find instructions for reading environment variable values in the programming languages that Elastic Beanstalk managed platforms support in the respective platform topic. For a list of links to these topics, see Environment variables and other software settings.

Secrets and parameters in Elastic Beanstalk environment variables

Elastic Beanstalk offers the ability to reference AWS Secrets Manager and AWS Systems Manager Parameter Store data in environment variables. This is a secure option for your application to natively access secrets and parameters stored by these services without having to manage API calls to them. Your Elastic Beanstalk Docker and ECS managed Docker platforms must be a version released on or after March 26, 2025 to support this feature. For more information about using environment variables to reference secrets, see Fetching secrets and parameters to Elastic Beanstalk environment variables.

Environments with Docker Compose

If you manage your Docker environment with Docker Compose, you must make some additional configuration to retrieve the environment variables in the containers. In order for the executables running in your container to access these environment variables, you must reference them in the docker-compose.yml. For more information see Referencing environment variables in containers.

Referencing environment variables in containers

If you are using the Docker Compose tool on the Amazon Linux 2 Docker platform, Elastic Beanstalk generates a Docker Compose environment file called .env in the root directory of your application project. This file stores the environment variables you configured for Elastic Beanstalk.

Note

If you include a .env file in your application bundle, Elastic Beanstalk will not generate an .env file.

In order for a container to reference the environment variables you define in Elastic Beanstalk, you must follow one or both of these configuration approaches.

• Add the .env file generated by Elastic Beanstalk to the env_file configuration option in the docker-compose.yml file.

• Directly define the environment variables in the docker-compose.yml file.

The following files provide an example. The sample docker-compose.yml file demonstrates both approaches.

• If you define environment properties DEBUG_LEVEL=1 and LOG_LEVEL=error, Elastic Beanstalk generates the following .env file for you:

  DEBUG_LEVEL=1
  LOG_LEVEL=error

• In this docker-compose.yml file, the env_file configuration option points to the .env file, and it also defines the environment variable DEBUG=1 directly in the docker-compose.yml file.

  services:
    web:
      build: .
      environment:
        - DEBUG=1
      env_file:
        - .env

Notes

• If you set the same environment variable in both files, the variable defined in the docker-compose.yml file has higher precedence than the variable defined in the .env file.

• Be careful to not leave spaces between the equal sign (=) and the value assigned to your variable in order to prevent spaces from being added to the string.

To learn more about environment variables in Docker Compose, see Environment variables in Compose

Using interpolate feature for environment variables with Docker Compose

Starting with the July 28, 2023 platform release, the Docker Amazon Linux 2 platform branch offers the Docker Compose interpolation feature. With this feature, values in a Compose file can be set by variables and interpolated at runtime. For more information about this feature, see Interpolation on the Docker documentation website.

Important

If you'd like to use this feature with your applications, be aware that you'll need to implement an approach that uses platform hooks.

This is necessary due a mitigation that we implemented in the platform engine. This mitigation ensures backward compatibility for customers that aren't aware of the new interpolation feature and have existing applications that use environment variables with the $ character. The updated platform engine escapes the interpolation by default by replacing the $ character with $$ characters.

The following is an example of a platform hook script that you can set up to allow use of the interpolation feature.

#!/bin/bash

: '
example data format in .env file
key1=value1
key2=value2
'
envfile="/var/app/staging/.env"
tempfile=$(mktemp)

while IFS= read -r line; do
  # split each env var string at '='
  split_str=(${line//=/ })
  if [ ${#split_str[@]} -eq 2 ]; then
    # replace '$$' with '$'
    replaced_str=${split_str[1]//\$\$/\$}
    # update the value of env var using ${replaced_str}
    line="${split_str[0]}=${replaced_str}"
  fi
  # append the updated env var to the tempfile
  echo "${line}" ≫"${tempfile}"
done < "${envfile}"
# replace the original .env file with the tempfile
mv "${tempfile}" "${envfile}"

Place the platform hooks under both of these directories:

• .platform/confighooks/predeploy/

• .platform/hooks/predeploy/

For more information, see Platform hooks in the Extending Linux platforms topic of this guide.

Generating logs for enhanced health reporting with Docker Compose

The Elastic Beanstalk health agent provides operating system and application health metrics for Elastic Beanstalk environments. It relies on web server log formats that relay information in a specific format.

Elastic Beanstalk assumes that you run a web server proxy as a container. As a result the NGINX web server proxy is disabled for Docker environments running Docker Compose. You must configure your server to write logs in the location and format that the Elastic Beanstalk health agent uses. Doing so allows you to make full use of enhanced health reporting, even if the web server proxy is disabled.

For instructions on how to do this, see Web server log configuration

Docker container customized logging with Docker Compose

In order to efficiently troubleshoot issues and monitor your containerized services, you can request instance logs from Elastic Beanstalk through the environment management console or the EB CLI. Instance logs are comprised of bundle logs and tail logs, combined and packaged to allow you to view logs and recent events in an efficient and straightforward manner.

Elastic Beanstalk creates log directories on the container instance, one for each service defined in the docker-compose.yml file, at /var/log/eb-docker/containers/<service name>. If you are using the Docker Compose feature on the Amazon Linux 2 Docker platform, you can mount these directories to the location within the container file structure where logs are written. When you mount log directories for writing log data, Elastic Beanstalk can gather log data from these directories.

If your applications are on a Docker platform that is not using Docker Compose, you can follow the standard procedure desribed in Docker container customized logging with Docker Compose.

To configure your service's logs files to be retreivable tail files and bundle logs

1. Edit the docker-compose.yml file.

2. Under the volumes key for your service add a bind mount to be the following:

   "${EB_LOG_BASE_DIR}/<service name>:<log directory inside container>

   In the sample docker-compose.yml file below:

   • nginx-proxy is <service name>

   • /var/log/nginx is <log directory inside container>

   services:
     nginx-proxy:
       image: "nginx"
       volumes:
         - "${EB_LOG_BASE_DIR}/nginx-proxy:/var/log/nginx"

• The var/log/nginx directory contains the logs for the nginx-proxy service in the container, and it will be mapped to the /var/log/eb-docker/containers/nginx-proxy directory on the host.

• All of the logs in this directory are now retrievable as bundle and tail logs through Elastic Beanstalk's request instance logs functionality.

Notes

• ${EB_LOG_BASE_DIR} is an environment variable set by Elastic Beanstalk with the value /var/log/eb-docker/containers.

• Elastic Beanstalk automatically creates the /var/log/eb-docker/containers/<service name> directory for each service in the docker-compose.ymlfile.

Docker images

The Docker and ECS managed Docker platform branches for Elastic Beanstalk support the use of Docker images stored in a public or private online image repository.

Specify images by name in Dockerrun.aws.json. Note these conventions:

• Images in official repositories on Docker Hub use a single name (for example, ubuntu or mongo).

• Images in other repositories on Docker Hub are qualified with an organization name (for example, amazon/amazon-ecs-agent).

• Images in other online repositories are qualified further by a domain name (for example, quay.io/assemblyline/ubuntu or account-id.dkr.ecr.us-east-2.amazonaws.com/ubuntu:trusty).

For environments using the Docker platform only, you can also build your own image during environment creation with a Dockerfile. See Building custom images with a Dockerfile for details. The ECS managed Docker platform doesn't support this functionality.

Configuring managed updates for Docker environments

With managed platform updates, you can configure your environment to automatically update to the latest version of a platform on a schedule.

In the case of Docker environments, you might want to decide if an automatic platform update should happen across Docker versions—when the new platform version includes a new Docker version. Elastic Beanstalk supports managed platform updates across Docker versions when updating from an environment running a Docker platform version newer than 2.9.0. When a new platform version includes a new version of Docker, Elastic Beanstalk increments the minor update version number. Therefore, to allow managed platform updates across Docker versions, enable managed platform updates for both minor and patch version updates. To prevent managed platform updates across Docker versions, enable managed platform updates to apply patch version updates only.

For example, the following configuration file enables managed platform updates at 9:00 AM UTC each Tuesday for both minor and patch version updates, thereby allowing for managed updates across Docker versions:

Example .ebextensions/managed-platform-update.config

option_settings:
  aws:elasticbeanstalk:managedactions:
    ManagedActionsEnabled: true
    PreferredStartTime: "Tue:09:00"
  aws:elasticbeanstalk:managedactions:platformupdate:
    UpdateLevel: minor

For environments running Docker platform versions 2.9.0 or earlier, Elastic Beanstalk never performs managed platform updates if the new platform version includes a new Docker version.

Docker configuration namespaces

You can use a configuration file to set configuration options and perform other instance configuration tasks during deployments. Configuration options can be platform specific or apply to all platforms in the Elastic Beanstalk service as a whole. Configuration options are organized into namespaces.

Note

This information only applies to Docker environment that are not running Docker Compose. This option has a different behavior with Docker environments that run Docker Compose. For further information on proxy services with Docker Compose see Container options.

The Docker platform supports options in the following namespaces, in addition to the options supported for all Elastic Beanstalk environments:

• aws:elasticbeanstalk:environment:proxy – Choose the proxy server for your environment. Docker supports either running Nginx or no proxy server.

The following example configuration file configures a Docker environment to run no proxy server.

Example .ebextensions/docker-settings.config

option_settings:
  aws:elasticbeanstalk:environment:proxy:
    ProxyServer: none

Docker configuration on Amazon Linux AMI (preceding Amazon Linux 2)

If your Elastic Beanstalk Docker environment uses an Amazon Linux AMI platform version (preceding Amazon Linux 2), read the additional information in this section.

Using an authentication file for a private repository

This information is relevant to you if you are using images from a private repository. Beginning with Docker version 1.7, the docker login command changed the name of the authentication file, and the format of the file. Amazon Linux AMI Docker platform versions (preceding Amazon Linux 2) require the older ~/.dockercfg format configuration file.

With Docker version 1.7 and later, the docker login command creates the authentication file in ~/.docker/config.json in the following format.

{
    "auths":{
      "server":{
        "auth":"key"
      }
    }
  }

With Docker version 1.6.2 and earlier, the docker login command creates the authentication file in ~/.dockercfg in the following format.

{
    "server" :
    {
      "auth" : "auth_token",
      "email" : "email"
    }
  }

To convert a config.json file, remove the outer auths key, add an email key, and flatten the JSON document to match the old format.

On Amazon Linux 2 Docker platform versions, Elastic Beanstalk uses the newer authentication file name and format. If you're using an Amazon Linux 2 Docker platform version, you can use the authentication file that the docker login command creates without any conversion.

Configuring additional storage volumes

For improved performance on Amazon Linux AMI, Elastic Beanstalk configures two Amazon EBS storage volumes for your Docker environment's Amazon EC2 instances. In addition to the root volume provisioned for all Elastic Beanstalk environments, a second 12GB volume named xvdcz is provisioned for image storage on Docker environments.

If you need more storage space or increased IOPS for Docker images, you can customize the image storage volume by using the BlockDeviceMapping configuration option in the aws:autoscaling:launchconfiguration namespace.

For example, the following configuration file increases the storage volume's size to 100 GB with 500 provisioned IOPS:

Example .ebextensions/blockdevice-xvdcz.config

option_settings:
  aws:autoscaling:launchconfiguration:
    BlockDeviceMappings: /dev/xvdcz=:100::io1:500

If you use the BlockDeviceMappings option to configure additional volumes for your application, you should include a mapping for xvdcz to ensure that it is created. The following example configures two volumes, the image storage volume xvdcz with default settings and an additional 24 GB application volume named sdh:

Example .ebextensions/blockdevice-sdh.config

option_settings:
  aws:autoscaling:launchconfiguration:
    BlockDeviceMappings: /dev/xvdcz=:12:true:gp2,/dev/sdh=:24

Note

When you change settings in this namespace, Elastic Beanstalk replaces all instances in your environment with instances running the new configuration. See Configuration changes for details.