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Build customization of aws-ecs-cloudreactor-deploy

aws-ecs-cloudreactor-deploy is a Docker image that is able to deploy Tasks to AWS ECS and CloudReactor. aws-ecs-cloudreactor-deploy uses Ansible to execute a playbook that includes steps to resolve the configuration properties, before deploying to both AWS and CloudReactor.

Out of the box, it only supports unencrypted secrets, or secrets encrypted with Ansible Vault. It is geared toward code written in dynamic languages that do not require compilation. However, you can customize the image to support other ways of handling secrets and additional build steps such as compilation.

Custom build steps

You can run custom build steps by adding steps to deploy_config/hooks/pre_build.yml and deploy_config/hooks/post_build.yml as necessary.

If you need to use libraries (e.g. compilers) not available in the aws-ecs-cloudreactor-deploy image, your custom build steps can either:

1) Use the docker command to build intermediate files (like JAR files or executables). Use docker build to build images, docker create to create containers, and finally, docker cp to copy files from containers back to the host. When docker runs in the container, it will use the host machine’s docker service.

2) Use build tools installed in the deployer image. In this case, you’ll want to create a new image based on cloudreactor/aws-ecs-cloudreactor-deployer:

FROM cloudreactor/aws-ecs-cloudreactor-deployer:1.1.0

# Example: get the JDK to build JAR files
RUN apt-get update && \
  apt-get -t stretch-backports install openjdk-11-jdk


Then set the DOCKER_IMAGE environment variable to the name of your new image, or change the deployment command in to use your new image instead of cloudreactor/aws-ecs-cloudreactor-deployer. Your ansible tasks can now use javac. If you create a Docker image for a specific language, we’d love to hear from you!

Also, check out multi-stage Dockerfiles as a way to build dependencies in the same Dockerfile that creates the final container. This may complicate the use of the same Dockerfile during development, however. configuration is what you’ll call on your host machine, which will run the Docker image for the deployer. The deployer Docker image has an entrypoint that executes the python script, which in turn, executes ansible-playbook.

The Ansible tasks in ansible/deploy.yml reference files that you can make available with Docker volume mounts. You can either modify to add or modify existing mounts, or configure the files/directories with environment variables. The Ansible tasks also read environment variables which you can set in deploy.env or deploy.<environment>.env.

You can configure some settings in with environment variables if you want to avoid modifying it:

Environment variable name Default value Description
DOCKER_CONTEXT_DIR Current directory The absolute path of the Docker context directory
DOCKERFILE_PATH Dockerfile Path to the Dockerfile, relative to the Docker context
CLOUDREACTOR_TASK_VERSION Empty A version number to report to CloudReactor. If empty, the latest git commit hash will be used.
PER_ENV_SETTINGS_FILE deploy.<environment>.env Path to a dotenv file containing environment-specific settings
EXTRA_DOCKER_RUN_OPTIONS Empty Additional options to pass to docker run
DEPLOY_COMMAND python The command to use when running the image. Can be set to bash for debugging.
DOCKER_IMAGE cloudreactor/aws-ecs-cloudreactor-deployer The Docker image to run. Can be set to another name in case you extend the image to add build tools.
DOCKER_IMAGE_TAG 1 The tag of the Docker image to run.

The behavior of ansible-playbook can be modified with many command-line options. To pass options to ansible-playbook, add --ansible-args to the end of the command-line for Follow that with all the options you want to pass to ansible-playbook. For example, to use secrets encrypted with ansible-vault and get the encryption password from the command-line during deployment:

./ staging --ansible-args --ask-vault-pass

Alternatively, you can use a password file:

./ staging --ansible-args --vault-password-file pw.txt

The password file could be a plaintext file, or a script like this:

echo `aws s3 cp s3://widgets-co/vault_pass.$DEPLOYMENT_ENVIRONMENT.txt -`

If you use a password file, make sure it is available in the Docker context of the container. You can either put it in your Docker context directory or add an additional mount option to the docker command-line.

More customization

You can customize the build even more by overriding any of the files in the ansible directory of aws-ecs-cloudreactor-deployer with you own version, by passing a volume mount option to the Docker command line. For example, to override ansible.cfg and deploy.yml, pass these options to the Docker command line in

-v $PWD/ansible_overrides/ansible.cfg:/work/ansible.cfg
-v $PWD/ansible_overrides/deploy.yml:/work/deploy.yml

aws-ecs-cloudreactor-deploy uses templates contained in /work/templates of its Docker image:

  • The ECS task definition is created with the Jinja2 template deploy/templates/ecs_task_definition.json.j2.
  • The CloudReactor Task is created with the Jinja2 template deploy/templates/cloudreactor_task.yml.j2. which produces a YAML file that is converted to JSON before sending it CloudReactor.

These templates use settings from the files described above. If you need to modify the templates, you can override the default templates similarly:

-v $PWD/ansible_overrides/templates/ecs_task_definition.json.j2:/work/templates/ecs_task_definition.json.j2