Cloud Platforms- sudo: unable to resolve host [closed]

Question

I use linux for my cloud based servers on Amazon-EC2 and openstack. When trying to run:

sudo chhown ubuntu somepath

I get this error every once in a while:

sudo: unable to resolve host

Most answers to this question on the internet are to edit the /etc/hosts file.

However, I deploy my servers automatically. besides that, I am not logging on using "localhost", but rather my AWS public DNS:

ssh -i mykey.pem [email protected]

So I cannot just trivially insert localhost, not to mention that my IP can change after I reset my machine. (Don't want to "waste" my precious floating IPs for every server)

Also, I deploy tens of servers at a time, so I cannot afford the manual step of editing a text file. Is there an automated fix for this issue? Recently I've started using openstack, and the issue is present there too.

Answer 1

EC2 instances inside VPC will resolve their auto-assigned internal hostnames correctly, only if you configure the VPC correctly. You need:

DNS hostnames: yes
DNS resolution: yes

http://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/vpc-dns.html

Answer 2

To resolve this problem I ran the following commands:

sudo vi /etc/hosts

Then in the hosts file that opens up add:

127.0.0.1     10.0.30.150

Obviously the 10.0.30.150 address would be the IP of the host in the warning message.