Google Compute Engine: how to set hostname permanently?

Question

How do I set the hostname of an instance in GCE permanently? I can set it via hostname,but after reboot it is gone again.

I tried to feed in metadata (hostname:f.q.d

Answer 1

Tested on Debian.

The dhclient sets the hostname using DHCP

You can override this by creating a custom hook script in /etc/dhcp/dhclient-exit-hooks.d/custom_set_hostname that would read the hostname from /etc/hostname:

if [ -f "/etc/hostname" ]; then
    new_host_name=$(cat /etc/hostname)
fi

The script must have the execute permission.

It's important to set the new_host_name variable and not calling the hostname command directly as any call to the hostname command will be overriden by another hook or the dhclient-script which uses this variable