How to avoid automatic change of Raspberry hostname

Few days ago I had to create several systems from one raspbian image. While trying to change hostname for each, I ran into an issue: although changing the entries in /etc/hostnames and /etc/hosts, the hostname reverted to the initial one after each reboot. I banged my head a bit and I found out that the culprit was a parameter in /etc/cloud/cloud.cfg.

By default, the setting is on false. In order to avoid resetting the hostname, you have to set preserve_hostname: true in your cloud.cfg. This stops the hostname from changing because it explicitly disables the internal cloud-init modules responsible for managing system identification.

Specifically, this setting affects the following:

• Disables Specific Modules: It tells cloud-init to skip the set_hostname and update_hostname modules entirely.
• Ignores Metadata: By default, cloud-init fetches a “local-hostname” from your cloud provider (like AWS or Azure) on every boot and overwrites /etc/hostname to match. With this flag set to true, cloud-init ignores those external metadata instructions.
• Fixes Manual Changes: Without this setting, manual changes made via commands like hostnamectl are often reverted back to the provider’s default name after a restart. Enabling it ensures your manual configuration remains persistent.

For a complete guide on managing these names, you can refer to the official cloud-init documentation on hostname updates.

Hope this helps.
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