Question: Running one-off tasks

[shinzui]

How do you run one-off tasks, such as running a script or a database migration against a container/task definition?

I currently have a very similar terraform setup but I run one-off tasks through the aws cli.

[achille-roussel]

Do you mean something that is repeated daily or just ad-hoc operations?

Cron jobs work well for the former, you could bake it into the AMI. Depending on your use case you can also have a "worker" in the form of an ECS task that just sleeps and runs at regular intervals or a "service" that executes your commands.

It's hard to tell what would be the best approach as this seems very use-case specific to me, if you wanna share more about what your needs are maybe we can come up with something interesting that could be added to stack.

[shinzui]

I was asking about ad-hoc operations such as running a script to fix some data, or running database migrations.... Currently, I duplicate my service task definition in terraform and omit the port mappings, then run aws ecs run-task against it with a command override to run a specific command.

[gregwebs]

That's a good solution I want to start using: seems like you just need to automate it (use terraform outputs plus the aws cli). I sometimes end up doing ssh + docker run/exec

[shinzui]

I use terraform's null_resource to generate the required ecs task cli input.

resource "null_resource" "batch_task_cli_input" {
  triggers {
    variables = "${data.template_file.batch_task_cli_input.rendered}"
  }

  provisioner "local-exec" {
    command = "echo '${data.template_file.batch_task_cli_input.rendered}' > ../../tmp/ecs-task-cli-input.json"
  }
}

[gregwebs]

I created a script for this. You will need to tweak it if you run multiple services in an ECS cluster: https://github.com/KariusDx/aws-scripts/blob/master/ecs-one-off