Cloud-init runs on every boot and resets your hostname to the value provided by the server's metadata. This is expected behavior, but it means any hostname you set manually will be overwritten on the next reboot.

There are two ways to make your hostname persistent.

Option 1: Prevent cloud-init from changing the hostname

Add preserve_hostname: true to your cloud-init configuration. This tells cloud-init to leave the hostname alone after the first boot.

Step 1: Edit the cloud-init config file on your server:

sudo nano /etc/cloud/cloud.cfg

Step 2: Find the line preserve_hostname and set it to true (or add it if it's missing):

preserve_hostname: true

Step 3: Set your desired hostname:

sudo hostnamectl set-hostname your-desired-hostname

Step 4: Verify it survives a reboot:

sudo reboot # After reconnecting: hostname

Option 2: Set the hostname via cloud-init user data

If you want cloud-init to actively set a specific hostname on every boot, define it in your user data. This is useful if you are provisioning new servers and want the hostname baked into the configuration.

Add the following to your cloud-config user data:

#cloud-config hostname: your-desired-hostname fqdn: your-desired-hostname.example.com preserve_hostname: true

The hostname key sets the short hostname, fqdn sets the fully qualified domain name, and preserve_hostname: true ensures subsequent boots do not override your setting with metadata from the datasource.

Which option should I use?

Still seeing the hostname reset?

Check whether your datasource is overriding the hostname at the network stage. You can inspect what cloud-init did on the last boot with:

sudo cat /var/log/cloud-init.log | grep -i hostname

If you see entries showing the hostname being set from metadata after your change, confirm that preserve_hostname: true is present and correctly indented in /etc/cloud/cloud.cfg.