HealthCheck on ECS task without an ELB

Solution 1:

The answer by raja and edite by Andrew are slightly off for ECS/FARGATE. It's without the brackets and without the quotes:

CMD-SHELL, curl -f http://localhost/ || exit 1

That is the correct format if entering Health check information inside Task Definitions of ECS.

VALID DOCUMENTATION https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task_definition_parameters.html#container_definition_healthcheck

NOT VALID DOCUMENTATION for ECS/FARGATE https://docs.aws.amazon.com/AmazonECS/latest/APIReference/API_HealthCheck.html

Solution 2:

The Given command is syntatically invalid.

it should be

[ "CMD-SHELL", "curl -f http://localhost/ || exit 1" ]

• CMD or CMD-SHELL - to run the command with the container's default shell
• curl -f http://localhost/ - actual command that need to be executed inside the container to validate the health check.
• exit 1 - if the curl command fail then it will exit the shell

so you should change your command like below.

[ "CMD-SHELL", "echo hi || exit 1" ]

echo hi is the helath check command in my example you can execute any command instead of "echo hi " whihc should return exit status 0 if that runs successfully in your container.

Solution 3:

If you use ecs-cli to deploy your fargate services, I found that you must upgrade to something that supports the healthcheck in the task definition. I also found that using CMD-SHELL is not required -- in fact, it breaks when you add it, wrapping your CMD-SHELL with another CMD-SHELL in the resulting json of the generated task definition (as seen in the aws console).

So what worked for me was upgrading from 1.4.0 to 1.7.0 of ecs-cli and then adding healthcheck in the ecs-params.yml file under the service:

task_definition:
  ecs_network_mode: awsvpc
  task_role_arn: arn:aws:iam::........
  task_execution_role: arn:aws:iam::........
  task_size:
    cpu_limit: 2048
    mem_limit: 4GB
  services:
    foo:
      healthcheck:
        command: ps cax | grep "[p]ython"
        interval: 30s
        timeout: 10s
        retries: 2
      essential: true

Solution 4:

For example, if your "Port mappings" is 8000:8000 for "ECS EC2" or 8000 tcp for "ECS Fargate", the "Command" of "HEALTHCHECK" is:

CMD-SHELL, curl -f http://localhost:8000/ || exit 1

Don't forget 8000 after http://localhost: in this case.