AWS ECS Error when running task: No Container Instances were found in your cluster

Im trying to deploy a docker container image to AWS using ECS, but the EC2 instance is not being created. I have scoured the internet looking for an explanation as to why I'm receiving the following error:

"A client error (InvalidParameterException) occurred when calling the RunTask operation: No Container Instances were found in your cluster."

Here are my steps:

1. Pushed a docker image FROM Ubuntu to my Amazon ECS repo.

2. Registered an ECS Task Definition:

aws ecs register-task-definition --cli-input-json file://path/to/my-task.json 

3. Ran the task:

aws ecs run-task --task-definition my-task

Yet, it fails.

Here is my task:

{
  "family": "my-task",
  "containerDefinitions": [
    {
        "environment": [],
        "name": "my-container",
        "image": "my-namespace/my-image",
        "cpu": 10,
        "memory": 500,
        "portMappings": [
            {
                "containerPort": 8080,
                "hostPort": 80
            }
        ],
        "entryPoint": [
            "java",
            "-jar",
            "my-jar.jar"
        ],
        "essential": true
    }
  ]
}

I have also tried using the management console to configure a cluster and services, yet I get the same error. How do I configure the cluster to have ec2 instances, and what kind of container instances do I need to use? I thought this whole process was to create the EC2 instances to begin with!!

I figured this out after a few more hours of investigating. Amazon, if you are listening, you should state this somewhere in your management console when creating a cluster or adding instances to the cluster:

"Before you can add ECS instances to a cluster you must first go to the EC2 Management Console and create ecs-optimized instances with an IAM role that has the AmazonEC2ContainerServiceforEC2Role policy attached"

Here is the rigmarole:

1. Go to your EC2 Dashboard, and click the Launch Instance button.

2. Under Community AMIs, Search for ecs-optimized, and select the one that best fits your project needs. Any will work. Click next.

3. When you get to Configure Instance Details, click on the create new IAM role link and create a new role called ecsInstanceRole.

4. Attach the AmazonEC2ContainerServiceforEC2Role policy to that role.

5. Then, finish configuring your ECS Instance.
NOTE: If you are creating a web server you will want to create a securityGroup to allow access to port 80.

After a few minutes, when the instance is initialized and running you can refresh the ECS Instances tab you are trying to add instances too.

Currently, the Amazon AWS web interface can automatically create instances with the correct AMI and the correct name so it'll register to the correct cluster.

Even though all instances were created by Amazon with the correct settings, my instances wouldn't register. On the Amazon AWS forums I found a clue. It turns out that your clusters need internet access and if your private VPC does not have an internet gateway, the clusters won't be able to connect.

The fix

In the VPC dashboard you should create a new Internet Gateway and connect it to the VPC used by the cluster. Once attached you must update (or create) the route table for the VPC and add as last line

0.0.0.0/0 igw-24b16740  

Where igw-24b16740 is the name of your freshly created internet gateway.

I ran into this issue when using Fargate. I fixed it when I explicitly defined launchType="FARGATE" when calling run_task.