What steps should be taken if a Compute Engine instance fails to launch?

When a Compute Engine instance fails to launch, it's essential to perform several checks to identify the underlying issue. The correct step to take involves assessing if the boot disk is completely full. When an instance launches, it requires proper access to the boot disk, which contains the operating system and other essential files required for the instance to operate correctly.

If the boot disk is full, the instance may struggle to read necessary files, write logs, or perform essential background processes, thereby preventing it from launching successfully. Ensuring that there is adequate space on the boot disk can resolve this issue and allow the instance to boot as expected.

While other troubleshooting steps like checking for file system corruption, accessing the instance with different SSH credentials, and examining firewall rules or networking routes are relevant in their contexts, they do not directly address the immediate problem of the instance's inability to launch related specifically to disk space concerns. Hence, verifying the boot disk's capacity is a critical first step in resolving launch failures for Compute Engine instances.