CloudWatch Flow Monitors no data from EKS Nodes

It sounds like you've correctly installed the AWS Network Flow Monitor Agent Add-On on your EKS cluster, and the logs you're seeing indicate that the agent is successfully sending data to the Network Flow Monitor ingestion APIs. The HTTP 200 status in the log entry suggests that the requests are being received and processed without errors.

However, there are a few things you can check to troubleshoot the lack of data in CloudWatch Flow Monitors:

1. Wait time: After installing the agents, it typically takes about 20 minutes for data to begin appearing in the Network Flow Monitor backend. If you haven't waited this long, give it some more time.

2. Permissions: Ensure that the IAM role associated with your EKS nodes or the service account (if using IRSA) has the necessary permissions to publish data to CloudWatch and interact with Network Flow Monitor.

3. Version compatibility: Make sure you're using a compatible version of the Network Flow Monitor Agent Add-On with your EKS cluster version.

4. Network connectivity: Verify that your EKS nodes have proper network connectivity to the CloudWatch and Network Flow Monitor endpoints.

5. CloudWatch configuration: Check that you're looking at the correct CloudWatch log group and region where the data should be appearing.

6. Add-On configuration: If you recently upgraded from version 1.0.0 to 1.0.1 of the AWS Network Flow Monitor Agent add-on, ensure that you followed the correct upgrade procedure. There was a known issue with the service account name change that could cause problems if not addressed during the upgrade.

If you've verified all these points and are still not seeing data, it may be worth contacting AWS Support for further assistance, as they can access more detailed information about your specific setup and any potential issues with the underlying infrastructure.
Sources
Install agents for self-managed Kubernetes instances - Amazon CloudWatch
Troubleshoot issues in Network Flow Monitor - Amazon CloudWatch
Initialize Network Flow Monitor - Amazon CloudWatch