Changing hostname on Ubuntu 18.04

So we have finally started rolling out 18.04 VM’s for corporate use at work (R1soft finally started rolling ‘non-beta’ modules, which was our main blocker), occasionally I’ll go to run up a bunch of VM’s and munge the hostname of one machine.. With cloud-init, it’s not quite a simple as editing /etc/hostname and rebooting anymore.. But it’s not too bad 🙂

First, edit /etc/cloud/cloud.cfg, and look for the preseve_hostname: field – you want this set to true.

#This will cause the set+update hostname module to not operate (if true)
preserve_hostname: true

Once done, run ‘hostnamectl’

root@prod-docker-manager-1:~# hostnamectl
   Static hostname: prod-docker-manager-1
         Icon name: computer-vm
           Chassis: vm
        Machine ID: 71431bc67882462ab8752997212223e8
           Boot ID: 2523f4f9cc3142b5bf56ad73f93da02e
    Virtualization: vmware
  Operating System: Ubuntu 18.04.2 LTS
            Kernel: Linux 4.15.0-45-generic
      Architecture: x86-64

This will show your current hostname. I guess you don’t need to really show this, it’s handy to know that it IS set as static. If it’s not, you’ll want to go google something 😉

You can now just run ‘hostnamectl set-hostname <newhostname>’

root@prod-docker-manager-1:~# hostnamectl set-hostname prod-swarm-manager-1
root@prod-docker-manager-1:~# hostnamectl
   Static hostname: prod-swarm-manager-1
         Icon name: computer-vm
           Chassis: vm
        Machine ID: 71431bc67882462ab8752997212223e8
           Boot ID: 2523f4f9cc3142b5bf56ad73f93da02e
    Virtualization: vmware
  Operating System: Ubuntu 18.04.2 LTS
            Kernel: Linux 4.15.0-45-generic
      Architecture: x86-64

And you’re good to go. Reboot if you have processes running which depend on the hostname. Or not if this is a brand new host (which is my usual case, where I’ve munged something during the VM install, and am now SSH’d in as the temporary local user to do the actual provisioning).

Published by Damien Gardner

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