ECS Fargate container does not have access to internet

Question

Hi,
I have created an ECS Cluster, with services and tasks attached to it.
The tasks have private and public IPs attached to it.
This is my own test environment, and thus I do not have a load balancer attached to it.
I have ensured that the security group, subnet, nacl have outbound access to port 443. (I used the default security group, nacl, VPC, subnets, but ensured I opened the required outbound and inbound ports).
However, when I run the curl command below in an amazon ecs exec bash prompt, I still get an error. The command hangs with no output :

```
 2025-02-01   17:00.08   /drives/c/Users/aigini.navaneethan  aws ecs execute-command   --cluster dummy_cluster   --task af679dbd69654c96b551b9c53b194a24   --container dummy-container   --interactive   --command "/bin/sh"

The Session Manager plugin was installed successfully. Use the AWS CLI to start a session.

Starting session with SessionId: ecs-execute-command-po3pbs3sal3zslx2b59kbhsiii
sh-4.2# curl -v https://infra-api.newrelic.com

```
I have tried so many things, however, still face this problem, and am not sure what else to do to fix this issue. Please assist me in this so that I can successfully access the internet from my ECS Fargate containers.

re:Post Agent · Answer

Based on the information provided, it appears that your ECS Fargate task is having difficulty accessing the internet despite having both private and public IPs attached. This issue can occur due to several reasons, even when security groups and network ACLs seem to be properly configured. Here are some potential causes and solutions to consider:

1. Subnet Configuration: Ensure that the task is running in a public subnet. If it's in a private subnet, it won't have direct internet access even with a public IP assigned. Public subnets should have a route table with a route to an Internet Gateway.

2. Auto-assign Public IP: For tasks in public subnets, make sure you have enabled "Auto-assign public IP" when launching the task. This is crucial for internet connectivity.

3. NAT Gateway: If your task is in a private subnet, you'll need to set up a NAT Gateway in your VPC and configure the route table of the private subnet to route internet-bound traffic through the NAT Gateway.

4. VPC Endpoints: If you're trying to access AWS services like ECR, consider using VPC endpoints to allow private communication without requiring internet access.

5. DNS Settings: Verify that DNS hostnames and DNS resolution are enabled for your VPC.

6. Container Configuration: Ensure that your container's network mode is set to 'awsvpc' in the task definition.

7. Task Execution Role: Verify that the task execution role has the necessary permissions to pull images and access required AWS services.

8. Firewall or Proxy: If your organization uses a firewall or proxy, ensure it's not blocking outbound connections from your VPC.

To troubleshoot further:
- Check the VPC Flow Logs to see if the traffic is being allowed or denied.
- Verify the route tables associated with your subnets.
- Try running a simple EC2 instance in the same subnet to test internet connectivity.
- Review the ECS task logs for any network-related errors.

If none of these solutions resolve the issue, you may need to review your VPC and ECS cluster configuration in more detail to identify any misconfigurations.  
**Sources**  
[Troubleshooting - Distributed Load Testing on AWS](https://docs.aws.amazon.com/solutions/latest/distributed-load-testing-on-aws/troubleshooting.html)  
[Allocate a network interface for an Amazon ECS task - Amazon Elastic Container Service](https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task-networking-awsvpc.html)  
[CannotPullContainer task errors in Amazon ECS - Amazon Elastic Container Service](https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task_cannot_pull_image.html)

ECS Fargate container does not have access to internet

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