How do I assign a static hostname to an Amazon EC2 Linux instance?

Resolution

Prerequisite: Create an Amazon Elastic Block Store (Amazon EBS)–backed Amazon Machine Image (AMI) of your EC2 instance.

Check the existing instance hostname

Complete the following steps:

1. Use SSH to connect to your Linux instance.

2. To switch to the root user, run the following command:

   sudo su -

3. To check the instance hostname, run the following command:

   hostnamectl

Configure a static hostname

Configure a static hostname for the operating system (OS) that you run.

AL2 or Al2023

For Amazon Linux 2 (AL2) or Amazon Linux 2023 (AL2023), complete the following steps:

1. To open /etc/cloud/cloud.cfg, run the following command:

   vim /etc/cloud/cloud.cfg

2. Make sure that the value for the preserve_hostname attribute is true.
   Example attribute:

   preserve_hostname: true

   Note: If the file doesn't have the preserve_hostname attribute, then add the attribute to the file.

3. To set the static hostname, run the following command:

   hostnamectl set-hostname persistent-hostname

   Note: Replace persistent-hostname with your hostname.

Ubuntu

Complete the following steps:

1. To set the static hostname, complete the following steps:

   hostnamectl set-hostname --static persistent-hostname

   Note: Replace persistent-hostname with your hostname.

2. To open /etc/hosts, run the following command:

   vim /etc/hosts

3. Enter the following line in the file:

   localhost persistent-hostname

   Note: Replace persistent-hostname with your hostname.

4. If your instance uses IPv6, then also enter the following configuration data:

   ::1 ip6-localhost ip6-loopback
   fe00::0 ip6-localnet
   ff00::0 ip6-mcastprefix
   ff02::1 ip6-allnodes
   ff02::2 ip6-allrouters
   ff02::3 ip6-allhosts

5. To open /etc/cloud/cloud.cfg, run the following command:

   vim /etc/cloud/cloud.cfg

6. Make sure that the value for the preserve_hostname attribute is true.
   Example attribute:

   preserve_hostname: true

RHEL or CentOS 8, 9, and 10

For Red Hat Enterprise Linux (RHEL) or CentOS 8, 9, and 10, complete the following steps:

1. To set the static hostname, run the following command:

   hostnamectl set-hostname --static persistent-hostname

   Note: Replace persistent-hostname with your hostname.

2. Run the following command to open /etc/cloud/cloud.cfg:

   vi /etc/cloud/cloud.cfg

3. Make sure that the value for the preserve_hostname attribute is true.
   Example attribute:

   preserve_hostname: true

SUSE Linux 12,15, and 16

For SUSE Linux Enterprise Server (SLES), complete the following steps:

1. To set the hostname, run the following command:

   hostnamectl set-hostname persistent-hostname

   Note: Replace persistent-hostname with your hostname.

2. To open /etc/hosts, run the following command:

   vim /etc/hosts

3. Enter the following line in the file:

   127.0.0.1 localhost persistent-hostname 

   Note: Replace persistent-hostname with your hostname.

4. To open /etc/cloud/cloud.cfg file, run the following command:

   vim /etc/cloud/cloud.cfg

5. Enter the following line in the file:

   preserve_hostname: true

Reboot the instance

To reboot the instance, run the following command:

reboot

To verify that the instance uses the new hostname after reboot, run the following command:

hostnamectl

Troubleshoot issues

If you still experience unexpected hostname changes after reboot, then take the following actions:

• Check the system logs at /var/log/cloud-init.log and /var/log/syslog for entries about hostname changes.
• If you installed system updates that affect /etc/hosts, the hostname file, or the hostname utility, then complete the resolution steps again.
• Verify that the preserve_hostname setting is true in the /etc/cloud/cloud.cfg file.

Related information

Change the hostname of your AL2 instance