Use ListTasks with an AWS SDK or CLI

    /// <summary>
    /// List task ARNs available.
    /// </summary>
    /// <param name="clusterARN">The arn of the ECS cluster.</param>
    /// <returns>The ARN list of tasks in given cluster.</returns>
    public async Task<List<string>> GetTaskARNsAsync(string clusterARN)
    {
        // Set up the request to describe the tasks in the service
        var listTasksRequest = new ListTasksRequest
        {
            Cluster = clusterARN
        };
        List<string> taskArns = new List<string>();

        // Call the ListTasks API operation and get the list of task ARNs
        var tasks = _ecsClient.Paginators.ListTasks(listTasksRequest);

        await foreach (var task in tasks.TaskArns)
        {
            if (task is null)
                continue;


            taskArns.Add(task);
        }

        if (taskArns.Count == 0)
        {
            _logger.LogWarning("No tasks found in cluster: " + clusterARN);
        }

        return taskArns;
    }

Example 1: To list the tasks in a cluster

The following list-tasks example lists all of the tasks in a cluster.

aws ecs list-tasks --cluster default

Output:

{
    "taskArns": [
        "arn:aws:ecs:us-west-2:123456789012:task/a1b2c3d4-5678-90ab-cdef-11111EXAMPLE",
        "arn:aws:ecs:us-west-2:123456789012:task/a1b2c3d4-5678-90ab-cdef-22222EXAMPLE"
    ]
}

Example 2: To list the tasks on a particular container instance

The following list-tasks example lists the tasks on a container instance, using the container instance UUID as a filter.

aws ecs list-tasks --cluster default --container-instance a1b2c3d4-5678-90ab-cdef-33333EXAMPLE

Output:

{
    "taskArns": [
        "arn:aws:ecs:us-west-2:123456789012:task/a1b2c3d4-5678-90ab-cdef-44444EXAMPLE"
    ]
}

For more information, see Amazon ECS Task Definitions in the Amazon ECS Developer Guide.

class EcsWrapper:
    """Encapsulates Amazon ECS operations."""

    def __init__(self, ecs_client: BaseClient):
        """
        Initializes the EcsWrapper with an ECS client.

        :param ecs_client: A Boto3 Amazon ECS client. Boto3 clients are created
            by the ``boto3.client`` factory function and are instances of
            ``botocore.client.BaseClient``, which is the correct type to
            annotate here (``boto3.client`` itself is a function, not a type).
        """
        self.ecs_client = ecs_client

    @classmethod
    def from_client(cls) -> "EcsWrapper":
        """Creates an EcsWrapper using a default Boto3 ECS client."""
        ecs_client = boto3.client("ecs")
        return cls(ecs_client)


    def list_tasks(
        self,
        cluster: str,
        service_name: Optional[str] = None,
    ) -> List[str]:
        """
        Lists task ARNs for a cluster, optionally filtered by service.
        Uses paginator to handle large result sets.

        :param cluster: The cluster name or ARN.
        :param service_name: The service name to filter by (optional).
        :return: A list of task ARN strings.
        :raises ClientError: If the request fails (e.g., InvalidParameterException).
        """
        try:
            task_arns = list()
            paginator = self.ecs_client.get_paginator("list_tasks")
            params = dict()
            params["cluster"] = cluster
            if service_name is not None:
                params["serviceName"] = service_name
            for page in paginator.paginate(**params):
                task_arns.extend(page.get("taskArns", list()))
            logger.info(
                "Listed %d tasks for cluster '%s'%s",
                len(task_arns),
                cluster,
                f" (service='{service_name}')" if service_name else "",
            )
            return task_arns
        except ClientError as err:
            if err.response["Error"]["Code"] == "InvalidParameterException":
                logger.error(
                    "Invalid parameter when listing tasks: %s",
                    err.response["Error"]["Message"],
                )
            raise