title: AWS ECS Error when running task: No Container Instances were found in your cluster
body: <p>Im trying to deploy a <code>docker</code> container image to <code>AWS</code> using <code>ECS</code>, 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: </p>
  
  <blockquote>
    <p>"A client error (InvalidParameterException) occurred when calling the RunTask operation: No Container Instances were found in your cluster."</p>
  </blockquote>
  
  <p><strong>Here are my steps:</strong> </p>
  
  <p>1. Pushed a docker image FROM Ubuntu to my Amazon ECS repo.</p>
  
  <p>2. Registered an ECS Task Definition:</p>
  
  <pre><code>aws ecs register-task-definition --cli-input-json file://path/to/my-task.json 
  </code></pre>
  
  <p>3. Ran the task: </p>
  
  <pre><code>aws ecs run-task --task-definition my-task
  </code></pre>
  
  <p>Yet, it fails.</p>
  
  <p><strong>Here is my task:</strong></p>
  
  <pre><code>{
    "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
      }
    ]
  }
  </code></pre>
  
  <p>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? <em>I thought this whole process was to create the EC2 instances to begin with!!</em></p>