Linux VMs in Azure
Unable to access serial console while booting
In Azure console output is sent to the log diagnostics console rather than the serial console when booting. This can cause issues as you cannot send commands to the console screen to manage any boot options the VM may be requesting.
To fix this you will need to access the GRUB boot menu. Select the recovery option and press "e"
Change the following:
linux /boot/vmlinuz-4.15.0-1023-azure root=UUID=21b294f1-25bd-4265-9c4e-d6e4aeb57e97 ro recovery nomodeset
change to
linux /boot/vmlinuz-4.15.0-1023-azure root=UUID=21b294f1-25bd-4265-9c4e-d6e4aeb57e97 ro recovery console=ttyS0
this will enable the console output to be sent to the serial console rather than the boot diagnostics
The same option can be used on the standard boot option - just remove the "recovery" command before "console=ttyS0"