Unexpected Reboot and EFI Shell Issue During the Reboot on AWS Node in a Self-hosted Kubernetes Cluster

the issue might lie with AWS (like a hardware issue or an unlogged AWS action) or with your EBS configuration, particularly since the instance failed to find a bootable device. Investigating along these lines while also considering any Kubernetes-related configurations would be a prudent approach.

The situation you're describing could be due to a few different factors. Let's address each of your questions:

1. Causes of Unexpected Reboot and Boot Device Issues:

   • AWS-initiated Reboot: If CloudTrail logs indicate no manual reboot events and AWS Health Dashboard shows no scheduled maintenance, it's possible that AWS initiated a reboot due to underlying hardware issues or health check failures.
   • Boot Device Issues: The message "No bootable device found" suggests a problem with the boot volume or configuration. This could be due to a corrupted boot volume, misconfiguration, or failure in the boot process.

2. Troubleshooting the EFI Shell Issue:

   • Check Boot Volume Configuration: Ensure that the boot volume is correctly attached to the instance and that the instance is configured to boot from it.
   • Verify Boot Volume Integrity: If possible, check the integrity of the boot volume. You may need to create a new boot volume or restore from a backup if the volume is corrupted.
   • Review EFI Shell Commands: Familiarize yourself with EFI Shell commands for diagnosing boot issues. You may need to use commands like map, fsX:, or ls to identify and access the boot volume.
   • Check Instance Logs: Review instance logs and system logs to see if there are any error messages or clues about what caused the boot failure.
   • AWS Support: If you're unable to resolve the issue, consider reaching out to AWS Support for assistance. They can help investigate potential underlying hardware issues or provide guidance on troubleshooting steps.

3. Issues with Kubernetes Clusters Deployed via Kops:

   • EBS Volume Configurations: While Kubernetes clusters deployed via Kops are generally reliable, there could be issues with EBS volume configurations or instance settings that impact the boot process. Ensure that your EBS volumes are correctly attached and configured within your Kubernetes cluster.
   • Instance Boot Settings: Double-check the instance boot settings to ensure they are configured correctly, especially if you're using custom AMIs or have made modifications to the instance configuration.

In summary, troubleshooting unexpected reboots and boot device issues on AWS EC2 instances requires a systematic approach, including verifying instance configurations, reviewing logs, and potentially reaching out to AWS Support for assistance. Pay special attention to the EFI Shell messages and instance boot settings to identify and resolve the underlying issue.