ECS EC2 Instance is not register to target group

Question

I create a ECS service using EC2 instances, then i create an Application Load Balancer and a target group, my docker image the task definition its using follow configuration:
```json
{
  "ipcMode": null,
  "executionRoleArn": null,
  "containerDefinitions": [
    {
      "dnsSearchDomains": null,
      "environmentFiles": null,
      "logConfiguration": {
        "logDriver": "awslogs",
        "secretOptions": null,
        "options": {
          "awslogs-group": "/ecs/onestapp-task-prod",
          "awslogs-region": "us-east-2",
          "awslogs-stream-prefix": "ecs"
        }
      },
      "entryPoint": null,
      "portMappings": [
        {
          "hostPort": 0,
          "protocol": "tcp",
          "containerPort": 80
        }
      ],
      "cpu": 0,
      "resourceRequirements": null,
      "ulimits": null,
      "dnsServers": null,
      "mountPoints": [],
      "workingDirectory": null,
      "secrets": null,
      "dockerSecurityOptions": null,
      "memory": null,
      "memoryReservation": 512,
      "volumesFrom": [],
      "stopTimeout": null,
      "image": "637960118793.dkr.ecr.us-east-2.amazonaws.com/onestapp-repository-prod:5ea9baa2a6165a91c97aee3c037b593f708b33e7",
      "startTimeout": null,
      "firelensConfiguration": null,
      "dependsOn": null,
      "disableNetworking": null,
      "interactive": null,
      "healthCheck": null,
      "essential": true,
      "links": null,
      "hostname": null,
      "extraHosts": null,
      "pseudoTerminal": null,
      "user": null,
      "readonlyRootFilesystem": false,
      "dockerLabels": null,
      "systemControls": null,
      "privileged": null,
      "name": "onestapp-container-prod"
    }
  ],
  "placementConstraints": [],
  "memory": "1024",
  "taskRoleArn": null,
  "compatibilities": [
    "EXTERNAL",
    "EC2"
  ],
  "taskDefinitionArn": "arn:aws:ecs:us-east-2:637960118793:task-definition/onestapp-task-prod:25",
  "networkMode": null,
  "runtimePlatform": null,
  "cpu": "1024",
  "revision": 25,
  "status": "ACTIVE",
  "inferenceAccelerators": null,
  "proxyConfiguration": null,
  "volumes": []
}
```
The service its using ALB and its using same Target Group as ALB, my task its running, and i can access using public ip from instance, but the target group does not have registered my tasks.

Answer

Thank you for reaching out to AWS!

To fix your issue, ensure you currently have your chosen target group.

You will then want to associate your target group with your application load balancer.

In order to register Amazon ECS tasks, you will want to create a Cluster in the ECS console.

* In the configure service section, confirm you have at least one task created
* And to use a load balancer, you must include "containerPort" in your definition
* Then in the Load Balancing Section, select Application Load Balancer and the Listener port used by your application
* Finally, select the existing target group you've created
* After creation, view your tasks and ensure they are RUNNING

These instructions can be found here:
https://aws.amazon.com/premiumsupport/knowledge-center/create-alb-auto-register/

I hope this helps and if you have any more questions, please feel free to reach out!

ECS EC2 Instance is not register to target group

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