sort ecs tasks in a cluster by memory reservation

sort_ecs_tasks_by_mem.py

#!/usr/bin/env python3
import boto3
import json
import sys
import os
import itertools

def chunks(l, n):
    for i in range(0, len(l), n):
        yield l[i:i + n]

def describe_all_tasks(**kwargs):
    ecs = boto3.client('ecs')
    paged_arns = chunks(kwargs['tasks'], 100)

    for arns in paged_arns:
        kwargs['tasks'] = arns
        resp = ecs.describe_tasks(**kwargs)
        yield from resp['tasks']

def base_taskdef_name(arn):
    bits = arn.split('/')
    name_rev = bits[-1]
    bits = name_rev.split(':')
    return bits[0]

if sys.stdout.isatty():
    os.execlp("bash", "bash", "-c", "%s %s %s | jq ." % (sys.executable, __file__, " ".join(sys.argv[1:])))

ecs = boto3.client('ecs')
cluster = sys.argv[1]

paginator = ecs.get_paginator('list_tasks')
it = paginator.paginate(cluster=cluster, desiredStatus='RUNNING')
arns = sum([page['taskArns'] for page in it], [])

tasks = list(describe_all_tasks(cluster=cluster, tasks=arns))
tasks.sort(key=lambda task: task['taskDefinitionArn'])
grouped = [(k, list(g)) for (k, g) in itertools.groupby(tasks, key=lambda task: base_taskdef_name(task['taskDefinitionArn']))]
memSum = [(arn, int(tasks[0]['memory']) * len(tasks)) for (arn, tasks) in grouped]
memSum.sort(key=lambda taskMem: -1 * taskMem[1])
taskmap = dict(memSum)

print(json.dumps(taskmap, default=str))