DNS does not resolve with NGINX in Kubernetes

Question

I have a kubernetes cluster with AWS. 

I'm trying to run a custom NGINX configuration which uses DNS resolutions to proxy_pass. 

location /api/v1/lead {
  resolver 10.3.0.10 ipv6=off;
  set $container lead-api;
  proxy_pass http://$container:3000;
}

I get the following error in the NGINX logs of the Kubernetes cluster

[error] 9#9: *20 lead-api could not be resolved (2: Server failure), client: 10.2.26.0, server: , request: "GET /api/v1/lead/661DF757-722B-41BB-81BD-C7FD398BBC88 HTTP/1.1"

Answer 1

use the Full Qualified Domain name. That is, you should use:

lead-api.<namespace>.svc.cluster.local

not just

lead-api

Answer 2

adding to @kalgi's answer

Using just the hostname will usually work because in kubernetes the resolv.conf is configured with search domains so that you don't usually need to provide a service's FQDN. e.g:

search default.svc.cluster.local svc.cluster.local cluster.local
nameserver 10.3.240.10
options ndots:5