ECS container Instances

Question

While deploy my CDK I  get an error:
```
service my-app was unable to place a task because no container instance met all of its requirements. 
Reason: No Container Instances were found in your cluster. 
For more information, see the Troubleshooting section of the Amazon ECS Developer Guide.
```
I re-checked everything. I have a autoscaling group in my code added and add it to the ECS cluster:

```
	const cluster = new Cluster(this, 'MyCluster', { vpc: this.mainVpc });

const ec2AutoScalingGroup = new AutoScalingGroup(this, 'todo-app-asg', {
			vpc: this.mainVpc,
			instanceType: new InstanceType('m6a.2xlarge'), 
			machineImage: EcsOptimizedImage.amazonLinux2(AmiHardwareType.STANDARD),
			desiredCapacity: 1,
			minCapacity: 1,
			maxCapacity: 10,
		  });

const capacityProvider = new AsgCapacityProvider(this, 'todo-app-capacity-provider', {
			autoScalingGroup: ec2AutoScalingGroup,
		  });
	  		  
		  cluster.addAsgCapacityProvider(capacityProvider);
```
While deploy the m6a.2xlarge Ec2 is available.

For my add Container I use a memory limit reservation:
memoryReservationMiB: 4096

I use Ec2TaskDefinition and Ec2Service, not Fargate

Why I get the Task deployment error?

re:Post Agent · Answer

The error you're encountering suggests that there are no container instances available in your ECS cluster to run your task. This can happen for several reasons, even if you've set up an Auto Scaling group and added it to the cluster. Here are some potential causes and solutions to consider:

1. IAM Role: Ensure that the EC2 instances in your Auto Scaling group have the correct IAM role attached. The instances need an IAM role that allows them to register with the ECS cluster. Check if you've defined and attached the appropriate IAM role to your EC2 instances.

2. ECS Agent: Verify that the ECS agent is running on your EC2 instances. The ECS-optimized AMI should have this pre-installed, but it's worth confirming that it's running and properly configured.

3. Networking: Make sure your EC2 instances are launching in the correct VPC and subnets, and that they have the necessary network access to communicate with the ECS service.

4. Instance Health: Check if your EC2 instances are launching successfully and passing health checks. Look in the EC2 console or CloudWatch logs for any issues with instance launch or initialization.

5. Capacity: Verify that your Auto Scaling group is actually launching instances. Sometimes, service quotas or other constraints can prevent instances from launching.

6. Task Definition Compatibility: Ensure that your task definition is compatible with EC2 launch type and that the resource requirements (CPU, memory) can be met by the instance type you've specified.

7. Cluster Recognition: Confirm that the EC2 instances are successfully joining the ECS cluster. You can check this in the ECS console under the "Container Instances" tab of your cluster.

8. Launch Template or User Data: If you're using a launch template or user data script, make sure it's correctly configured to join the ECS cluster.

To troubleshoot, you can:
- Check the Auto Scaling group in the EC2 console to see if instances are launching.
- Look at CloudWatch logs for the EC2 instances and ECS agent logs for any error messages.
- Verify in the ECS console that container instances are registered to your cluster.
- Temporarily increase the desired capacity of your Auto Scaling group to ensure new instances are being launched.

If none of these solve the issue, you may need to review your CDK code to ensure all components are correctly defined and linked, especially the connection between the Auto Scaling group, capacity provider, and the ECS cluster.  
**Sources**  
[Amazon ECS service event messages - Amazon Elastic Container Service](https://docs.aws.amazon.com/AmazonECS/latest/developerguide/service-event-messages-list.html)  
[Deploying Containers on AWS: A Guide to ECS and EKS | AWS re:Post](https://repost.aws/articles/ARMYRTVoV1RKSs-0Zy1S2LgA/deploying-containers-on-aws-a-guide-to-ecs-and-eks)

ECS container Instances

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