[Software] It's been a long time coming but AWS has at last enabled an interactive serial console for de-borking VMs.

[S9OUL.]

AWS has introduced the "interactive EC2 Serial Console", enabling troubleshooting of virtual machines when normal SSH access is not working, with one user gushing: "I have been waiting 10 years for this moment."

The purpose of serial console access is to enable troubleshooting when an SSH connection is impossible, for example, because of an out-of-memory condition. "It provides a one-click, text-based access to an instances' serial port as though a monitor and keyboard were attached to it," said the AWS post. Previously, admins could see serial console logs, using the command get-console-output, but not enter any commands.

Back in January 2011, a user reported on the AWS forum (login required) about a case where the console output was "Continue to wait; or Press S to skip mounting or M for manual recovery."

Unfortunately, "there is no way for me to hit 'S'," he said.

Reasons he gave for requiring the interactive console feature included when boot failed and the SSH daemon did not start, errors configuring the firewall or network which blocked all access, broken networking on the instance, or denial-of-service attacks. This person was building a base instance for a system image, which is the kind of case where fatal errors are more likely.

Admins confronted with an inaccessible EC2 (Elastic Compute Cloud) VM may have another option, which is to stop the instance, detach the storage, mount the storage on a working instance, and edit or recover the files from there. This is not always possible, though.

If the VM uses instance type storage, this cannot be detached. It also requires interruption of service. "I had a customer once that erased their SSH keys, and had a running database cluster on EC2 that they couldn't get access to anymore. That was... fun," said a user on Hacker News, looking forward to the new feature.