As a Linux System admin, we always love to work on CentOS and RHEL. In my case i had to launch a CentOS7 instance from the AWS Marketplace again. When we set the hostname with hostnamectl and reboot, yes the Instance comes with the default hostname again. So i have thought of documenting it here, so that it may be helpful for you as well !!

Issue

You have launched a CentOS 7 Instance from AWS Marketplace.
You have ran hostnamectl and rebooted the instance, but the hostname didnt became persistent.

Solution

Set hostname with hostnamectl command

hostnamectl set-hostname server1.example.com

Assign the hostname in /etc/sysconfig/network file

vim /etc/sysconfig/network
NETWORKING=yes
NOZEROCONF=yes
HOSTNAME=server1.example.com

Update the cloud.cfg file and set preserve_hostname to true
```
vi /etc/cloud/cloud.cfg
preserve_hostname: true
```
Now reboot the server
```
reboot
```
The server will bootup with the new persistent hostname. Please comment, if you have faced any issues with this.