AWS EC2 ECS No Container Instances were found in your cluster

Question

I want to deploy a dockerized python app using ECS, I followed this tutorial but ran into problems:

https://www.youtube.com/watch?v=zs3tyVgiBQQ

The cluster is created and an ECS instance appears in the EC2 menu: https://ibb.co/GR1SMDD

But no ECS instances appear in the ECS menu: https://ibb.co/QjwypHt

I created a task and defined a container, similar to what's shown at that point in the video: https://youtu.be/zs3tyVgiBQQ?t=619

When I'm about to run a new task, in the cluster menu, most fields are already filled with what I wrote for the task above, but when I 'run task', this happens: https://ibb.co/BPvG6rh

Unable to run task

No Container Instances were found in your cluster.

I've been looking for solutions for a few days now, but I'm new to AWS, and I'm running out of ideas, so any help on how to solve this, step-by-step, is very appreciated

Answer 1

If you haven't wrote your user-data with your ecs cluster name, then your EC2 instances will not register with the cluster. You have to explicitly register them with the cluster using user-data:

#!/bin/bash
echo "ECS_CLUSTER=MyClusterName" >> /etc/ecs/ecs.config

as explained in Bootstrapping container instances with Amazon EC2 user data .