Set a Hostname for Each Instance

*Execute the following commands for each Node.

Once the instances are created, set a hostname for each node and then add an entry to /etc/hosts file so that the nodes can locate each other. You can also use DNS if it’s available in your environment.

1. use hostnamectl command to set a hostname:

$ sudo su -
# hostname 
ip-10-20-1-10.us-west-2.compute.internal 
# hostnamectl set-hostname node-a

2. If a DNS server is available, register your hostname(s) using the server. If there is not a DNS server available, using /etc/hosts is recommended to resolve the hostnames.

# cat /etc/hosts 
127.0.0.1	localhost localhost.localdomain localhost4 localhost4.localdomain4 
::1 		localhost localhost.localdomain localhost4 localhost4.localdomain4 

3. Add the following lines to the /etc/hosts file so that node-a and node-b can be resolved to an IP address(es).

10.20.1.10	node-a
10.20.2.10 	node-b 
10.20.3.10 	node-c 

4. Create a backup of /etc/hosts, edit the file and confirm the changes.

# cp -p /etc/hosts /etc/hosts.org 
# vi /etc/hosts 
# cat /etc/hosts 
127.0.0.1	localhost localhost.localdomain localhost4 localhost4.localdomain4 
::1 		localhost localhost.localdomain localhost4 localhost4.localdomain4 
10.20.1.10 node-a
10.20.2.10 node-b 
10.20.3.10 node-c

5. Make sure you can ping these nodes by name.

# ping node-b 
PING node-b (10.20.2.10) 56(84) bytes of data. 
64 bytes from node-b (10.20.2.10): icmp_seq=1 ttl=64 time=0.868 ms 
64 bytes from node-b (10.20.2.10): icmp_seq=1 ttl=64 time=0.892 ms 
^C