I'm having a tough day trying to get my ECS setup to work. I've created a container definition inside a task definition and set up a service within an ECS cluster. My VPC is configured with three subnets across different availability zones, and there's a private endpoint connected to ECR. I also have a security group in place that should permit all of these components to communicate. Additionally, I've assigned a task execution role that has permissions for ECR and CloudWatch Logs.
However, I'm encountering an issue where ECS is failing to pull the necessary task from ECR, and I'm not sure why. The SSM runbook "TroubleshootECSTaskFailedToStart" completes a few steps before reporting success, but it doesn't provide any helpful output. I'm looking for examples of a complete Terraform stack for creating an ECS service if anyone has one. More importantly, does anyone have insights on why ECS might be struggling to pull from RDS?
As an update, I finally got the following error:
Task stopped at: 2026-02-08T00:42:44.811Z
`ResourceInitializationError: unable to pull secrets or registry auth: The task cannot pull registry auth from Amazon ECR: There is a connection issue between the task and Amazon ECR. Check your task network configuration. operation error ECR: GetAuthorizationToken, exceeded maximum number of attempts, 3, https response error StatusCode: 0, RequestID: , request send failed, Post "https://api.ecr.us-west-2.amazonaws.com/": dial tcp 34.223.24.13:443: i/o timeout`
I suspect my ECR interface endpoint might be configured incorrectly as it points to com.amazonaws.us-west-2.ecr.dkr with a private IP of 10.0.x.y. Did I set up the endpoint for the wrong service?
5 Answers
It sounds like your private endpoint to ECR could be causing this issue. If you're operating in a private subnet without a NAT gateway, you might need separate endpoints for different services. Double-check your configuration and make sure you've got the right endpoints set to allow ECS to pull the images properly.
I can relate to your struggles. When I set up ECS in a private subnet, it took time to get the configurations right. Make sure you have both the `com.amazonaws.region.ecr.api` and the `com.amazonaws.region.ecr.dkr` configured. Also, double-check the security group rules to ensure that 443 is open for all the endpoints.
Don't forget to verify the permissions! ECS needs certain permissions to retrieve images from ECR. Ensure the task execution role includes permissions like `ecr:GetAuthorizationToken`. Also, check that you've set up the VPC Gateway endpoint for S3, as that can often be overlooked.
You definitely need to look closely at your endpoint configurations. The errors suggest that requests are hitting public IPs instead of going through private IPs as needed with a properly configured interface endpoint for ECR. Make sure you've set up all required endpoints for a successful image pull.
Have you shared your Terraform code? Seeing the whole stack could help pinpoint where things might be going wrong. Sometimes, a small detail gets overlooked in the code that can cause these timeouts.
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