# How Can a Changed Static Hostname Take Effect Permanently?

#### Symptom

The static hostname of a Linux ECS is user defined and injected using Cloud-Init during the ECS creation. Although the hostname can be changed by running the hostname command, the changed hostname is restored after the ECS is restarted.

#### Changing the Hostname on the ECS

To make the hostname changed by running the hostname command take effect even after the ECS is stopped or restarted, save the changed hostname into configuration files.

The changed hostname is assumed to be new_hostname.

1. Modify the /etc/hostname configuration file.

   1. Run the following command to edit the configuration file:

      sudo vim /etc/hostname

   2. Change the hostname to the new one.
   3. Run the following command to save and exit the configuration file:

      :wq

2. Modify the /etc/sysconfig/network configuration file.

   1. Run the following command to edit the configuration file:

      sudo vim /etc/sysconfig/network

   2. Change the HOSTNAME value to the new hostname.

      HOSTNAME=Changed hostname

      If there is no HOSTNAME in the configuration file, manually add this parameter and set it to the changed hostname.

      An example is provided as follows:

      HOSTNAME=new_hostname

   3. Run the following command to save and exit the configuration file:

      :wq

3. Modify the /etc/cloud/cloud.cfg configuration file.

   1. Run the following command to edit the configuration file:

      sudo vim /etc/cloud/cloud.cfg

   2. Use either of the following methods to modify the configuration file:
      - Method 1: Change the preserve_hostname parameter value or add the preserve_hostname parameter to the configuration file.

        If preserve_hostname: false is already available in the /etc/cloud/cloud.cfg configuration file, change it to preserve_hostname: true. If preserve_hostname is unavailable in the /etc/cloud/cloud.cfg configuration file, add preserve_hostname: true before cloud_init_modules.

        If you use method 1, the changed hostname still takes effect after the ECS is stopped or restarted. However, if the ECS is used to create a private image and the image is used to create a new ECS, the hostname of the new ECS is the hostname (new_hostname) used by the private image, and user-defined hostnames cannot be injected using Cloud-Init.

      - Method 2 (recommended): Delete or comment out - update_hostname.

        If you use method 2, the changed hostname still takes effect after the ECS is stopped or restarted. If the ECS is used to create a private image and the image is used to create a new ECS, the changed hostname permanently takes effect, and user-defined hostnames (such as new_new_hostname) can be injected using Cloud-Init.

4. Run the following command to restart the ECS:

   sudo reboot

5. Run the following command to check whether the hostname has been changed:

   sudo hostname

   If the changed hostname is displayed in the command output, the hostname has been changed and the new name permanently takes effect.

Parent topic: ECS Management