Automate GCP persistent disk initialization
The marked answer did not work for me as the sudo blkid /dev/sdb
part always returned a value (hence, true) and the script would exit.
I updated the script to check for the entry in fstab
and added safety options to the script.
#!/bin/bash
set -uxo pipefail
MNT_DIR=/mnt/disks/persistent_storage
DISK_NAME=my-disk
# Check if entry exists in fstab
grep -q "$MNT_DIR" /etc/fstab
if [[ $? -eq 0 ]]; then # Entry exists
exit
else
set -e # The grep above returns non-zero for no matches & we don't want to exit then.
# Find persistent disk's drive value, prefixed by `google-`
DEVICE_NAME="/dev/$(basename $(readlink /dev/disk/by-id/google-${DISK_NAME}))"
sudo mkfs.ext4 -m 0 -F -E lazy_itable_init=0,lazy_journal_init=0,discard $DEVICE_NAME
sudo mkdir -p $MOUNT_DIR
sudo mount -o discard,defaults $DEVICE_NAME $MOUNT_DIR
# Add fstab entry
echo UUID=$(sudo blkid -s UUID -o value $DEVICE_NAME) $MNT_DIR ext4 discard,defaults,nofail 0 2 | sudo tee -a /etc/fstab
fi
Here's the gist if you want to download it - https://gist.github.com/raj-saxena/3dcaa5c0ba0be88ed91ef3fb50d3ce85
Have you considered using a startup script on the instance (I presume you can also add a startup-script with Terraform)? You could use an if
loop to discover if the disk is formatted, then if not, you could try running the formatting/mounting commands in the documentation you linked (I realise you have suggested you do not want to follow the manual steps in the documentation, but these can be integrated into the startup script to achieve the desired result).
Running the following outputs and empty string if the disk is not formatted:
sudo blkid /dev/sdb
You could therefore use this in a startup script to discover if the disk is formatted, then perform formatting/mounting if that is not the case. For example, you could use something like this (Note*** If the disk is formatted but not mounted this could be dangerous and should not be used if your use case could involve existing disks which may have already been formatted):
#!/bin/bash
if sudo blkid /dev/sdb;then
exit
else
sudo mkfs.ext4 -m 0 -F -E lazy_itable_init=0,lazy_journal_init=0,discard /dev/sdb; \
sudo mkdir -p /mnt/disks/newdisk
sudo mount -o discard,defaults /dev/sdb /mnt/disks/newdisk
fi