Getting list of running containers from a cluster

Question

I am running docker containers on an AWS via ECS. I have setup a cluster with some basic configuration.

Now I am looking forward to get no. of all running containers on this cluster (spread across 2-3 EC2 instances)? Does AWS / Docker provide any API for this?

I know on a container instance, doing docker ps -a will return me list of all running / stopped containers, while docker ps will return running containers on one system. But I want an API (which can be called from outside) or command (which I can run on any of the instance part of the cluster) and it shows me total number of running containers across cluster?

Answer 1

In ECS you're looking at tasks. You can list all running tasks with the ECS API. With the aws cli, for example, you can do:

aws ecs list-tasks --cluster <cluster_name>

If you use one of the SDKs, for example boto3, you can obtain the count easily:

import boto3

client = boto3.client('ecs')

tasks = client.list_tasks(cluster='YouCluster')

print(len(tasks['taskArns'])