Why an Entry Is Automatically Added to /etc/hosts After a Linux ECS Is Restarted?

Symptom

After an ECS is restarted, an entry that maps its host name to 127.0.0.1 is automatically added to /etc/hosts. As a result, the host name fails to be resolved.

Root Cause

/etc/cloud/cloud.cfg affects the following configuration in /etc/hosts:

 manage_etc_hosts: localhost

This configuration automatically translates the host names to the local loopback address, which can speed up startup when the private DNS is not configured.

Solution

1. Open the /etc/cloud/cloud.cfg file.

   Comment out manage_etc_hosts:

   Before:

   manage_etc_hosts:localhost

   After:

   #manage_etc_hosts:localhost

2. Delete 127.0.0.1 hostname hostname from /etc/hosts.