I am deploying a java app on aws ecs fargate in an aws account(aws-dev) and it is working perfectly fine. My app makes call to get the local host and able to resolve it.

InetAddress.getLocalHost()

On app startup, i printed contents of /etc/hosts and it looks like this:

127.0.0.1 localhost
10.111.11.111 ip-10-111-11-111.ec2.internal

Everything works fine till this point.

Now i got another aws account (aws-uat) and deployed the same app(same docker image) to ecs fargate but i am getting unknown host error.

java.net.UnknownHostException: 718ec01ffa6a11dea91ea43ea6d18328-1111111111: 718ec01ffa6a11dea91ea43ea6d18328-1111111111: System error

And reason for this error looks like is, /etc/hosts is different in this account. Here /etc/hosts content are as per mentioned below and hostname mapping is missing:

127.0.0.1 localhost
10.11.11.111

My question why container running from same docker image on aws ecs fargate would have different /etc/hosts and why hostname is not getting mapped to ip in later case ? Is this something related to aws networking between the 2 accounts, if yes what it could be and how to resolve it ? Or something else is wrong here ?

CodePudding user response：

You should check the DNS options in the VPC each of these is running in. I'm guessing you may have DNS Support or DNS Hostnames disabled in the second VPC.