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Amazon ECS 0.35.14Last updated in version 0.35.3

ECS Deployment Scripts

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This folder contains scripts that help with ECS deployment:

  • run-ecs-task: Run a single ECS Task, wait for it to exit, and return the exit code of the first container in that Task. This is useful for running short-lived ECS Tasks (e.g., an ECS Task that takes a backup of your data or runs a schema migration) and ensuring those ECS Tasks complete successfully. For example, if you had a database that lived in private subnets and you wanted a reliable and repeatable way to apply schema migrations to that database before deploying your apps, you could package the schema migration code in a Docker container and update your automated deployment process to use the run-ecs-task script to run that Docker container in an ECS Cluster that can access the database. If the schema migration completes successfully, the deployment continues; if it fails, run-ecs-task will exit with a non-zero exit code, and the deployment will be halted.

Installing the scripts

You can install the helpers using the Gruntwork Installer:

gruntwork-install --module-name "ecs-deploy" --repo "https://github.com/gruntwork-io/terraform-aws-ecs" --tag "v0.7.0"

Using the run-ecs-task script

The run-ecs-task script assumes you already have the following:

  1. An ECS Cluster deployed. The easiest way to deploy one is with the ecs-cluster module. You'll need to know the name of the cluster and the AWS region in which it is deployed.

  2. An ECS Task Definition defined. The easiest way to create one is with the aws_ecs_task_definition resource. You'll need to know the family name and revision of the ECS Task Definition you want to run.

Check out the deploy-ecs-task example for working sample code of both of the above.

To run the ECS Task Definition db-backup at revision 3 in an ECS Cluster named ecs-stage in us-west-2, use the following command:

run-ecs-task --task db-backup:3 --cluster ecs-stage --region us-west-2 --timeout 600

The command will do the following:

  1. Run db-backup as an ECS Task in the ecs-stage Cluster.
  2. Wait for the db-backup ECS Task to exit up to 600 seconds (exit with an error if the Task takes longer to run).
  3. Read the exit code for the Task and exit with that same code.

If your ECS Task runs successfully and exits with an exit code of 0, run-ecs-task will also exit with a code of 0; if your ECS Task hits an error and exits with a non-zero exit code, run-ecs-task will exit with the same non-zero exit code. This is particularly useful as part of an automated deployment, as it ensures subsequent deployment steps don't run if running the ECS Task failed.

Override the container command

The default operation of run-ecs-task is to run an ECS task using the configurations of the ECS Task Definition, including the container commands to run. However, there are certain use cases where it is desirable to avoid maintaining a separate Task Definition for each one off command you want to run. For example, in a Python Django project, it may be easier to run database migrations using the web application ECS Task Definition and invoking the ./manage.py migrate command.

run-ecs-task allows you to override the container command. To override the container command, provide the container name for which the command is applied to and pass in the command using positional args. For example, to override the command to python manage.py migrate in the django container of the my-app ECS task definition:

run-ecs-task --task my-app:3 --cluster ecs-stage --region us-west-2 --timeout 600 --container django -- python manage.py migrate

This will spin up a new ECS task using the my-app revision 3 ECS Task Definition, and run the python manage.py migrate command in the django container instead of the command configured in the Task Definition.