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Deployment guide: Guestbook one-off task

In this example, you will learn how to use layer0 to run a one-off task. A task is used to run a single instance of your Task Definition and is typically a short running job that will be stopped once finished.

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Before you start

In order to complete the procedures in this section, you must install and configure Layer0 v0.8.4 or later. If you have not already configured Layer0, see the installation guide. If you are running an older version of Layer0, see the upgrade instructions.

Part 1: Prepare the task definition

1. Download the Guestbook One-off Task Definition and save it to your computer as Dockerrun.aws.json.

Part 2: Create a deploy

Next, you will create a new deploy for the task using the deploy create command. At the command prompt, run the following command:

l0 deploy create Dockerrun.aws.json one-off-task-dpl

You will see the following output:

DEPLOY ID           DEPLOY NAME        VERSION
one-off-task-dpl.1  one-off-task-dpl   1

Part 3: Create the task

At this point, you can use the task create command to run a copy of the task.

To run the task, use the following command:

l0 task create demo-env echo-tsk one-off-task-dpl:latest --wait

You will see the following output:

TASK ID       TASK NAME         ENVIRONMENT  DEPLOY              SCALE
one-off851c9  echo-tsk          demo-env     one-off-task-dpl:1  0/1 (1)

The SCALE column shows the running, desired and pending counts. A value of 0/1 (1) indicates that running = 0, desired = 1 and (1) for 1 pending task that is about to transition to running state. After your task has finished running, note that the desired count will remain 1 and pending value will no longer be shown, so the value will be 0/1 for a finished task.

Part 4: Check the status of the task

To view the logs for this task, and evaluate its progress, you can use the task logs command:

l0 task logs echo-tsk

You will see the following output:

alpine
------
Task finished!

You can also use the following command for more information in the task.

l0 -o json task get echo-tsk

Outputs:

[
    {
        "copies": [
            {
                "details": [],
                "reason": "Waiting for cluster capacity to run",
                "task_copy_id": ""
            }
        ],
        "deploy_id": "one-off-task-dpl.2",
        "deploy_name": "one-off-task-dpl",
        "deploy_version": "2",
        "desired_count": 1,
        "environment_id": "demoenv669e4",
        "environment_name": "demo-env",
        "pending_count": 1,
        "running_count": 0,
        "task_id": "echotsk1facd",
        "task_name": "echo-tsk"
    }
]

After the task has finished, running l0 -o json task get echo-tsk will show a pending_count of 0.

Outputs:

...
"copies": [
    {
        "details": [
            {
                "container_name": "alpine",
                "exit_code": 0,
                "last_status": "STOPPED",
                "reason": ""
            }
        ],
        "reason": "Essential container in task exited",
        "task_copy_id": "arn:aws:ecs:us-west-2:856306994068:task/0e723c3e-9cd1-4914-8393-b59abd40eb89"
    }
],
...
"pending_count": 0,
"running_count": 0,
...