How to set a persistant FQDN for an Ubuntu 18.04 droplet?

Question

Hi,

I created a new droplet today. Named it ‘fred’. If I query the hostname, it returns ‘fred’. If I ask for the FQDN via hostname --fqdn, I get ‘fred’.

My DNS (external provider) is pointing at ‘fred.example.org’.

Reading various articles here, I’ve tried changing the name of the droplet via the control panel (no change after a reboot), using the hostname command (lasts until the next reboot), using the hostnamectl command, which seems to change the hostname and the FQDN to ‘fred.example.org’.

Normally, I’d change the hostname file and the resolv.conf file. But, both files have comments that they should be changed elsewhere in part of the cloud init system. Which seems to be tied into systemd.

This will be a mail server, eventually, and its really important to get the names set up properly.

I keep looking for a tutorial that would address this with the specifics of the Digital Ocean setup, but I’m not finding it.

What am I missing?

Thanks,

johnbo

Bobby Iliev · Answer

Hello,

I believe that there are 3 things that you need to do:

Change the hostname with the hostnamectl command:

sudo hostnamectl set-hostname fred.example.org

Update your hostname in your hosts file:

vim /etc/hosts

Find the references to the old FQDN and update them to the new one.

Update the cloud.cfg file. Edit the following file:

vim /etc/cloud/cloud.cfg

Find the reference for preserve_hostname and change it from false to true.

That is pretty much it, you can try to reboot your server and then test the change by running only the hostnamectl command.

Hope that this helps! Regards, Bobby

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How to set a persistant FQDN for an Ubuntu 18.04 droplet?

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