How to make request to nginx server_name in kubernetes

Question

I have deployed nginx in my kubernetes cluster with this configmap:

apiVersion: v1
data:
  json.conf: |-
    server {
      listen 80;
      server_name api.test.com;
      location / {
        proxy_pass https://jsonplaceholder.typicode.com/posts;
        proxy_http_version 1.1;
        proxy_set_header Connection "";
        proxy_buffering off;
        proxy_redirect off;
        proxy_ssl_server_name on;
        proxy_ssl_protocols TLSv1.2 TLSv1.3;
        proxy_ssl_verify off;
      }
    }
kind: ConfigMap
metadata:
  name: json
  namespace: app

My problem is when I want to request this nginx pod from another pod, I have to call the nginx pod's service in Kubernetes but I want to call for example http://api.test.com in my request. How can handle this?

I have tried this in (for example in api-app-chart-f5bbcf55d-fthbz):

curl http://nginx-egress-app-chart-svc-web

But i want to request like this:

curl http://api.test.com

Answer 1

You can implement it with rewrite feature of CoreDNS.

Add this line to CoreDNS config file. (NOTE: replace <namespace>)

rewrite name api.test.com nginx-egress-app-chart-svc-web.<namespace>.svc.cluster.local

.:53 {
    errors
    health  {
        lameduck 5s
    }
    rewrite name api.test.com nginx-egress-app-chart-svc-web.<namespace>.svc.cluster.local
    ready 
    kubernetes   cluster.local  cluster.local in-addr.arpa ip6.arpa {
        pods insecure
        fallthrough in-addr.arpa ip6.arpa
        ttl 30
    }
    prometheus   0.0.0.0:9153
    forward   . /etc/resolv.conf
    cache   30
    loop 
    reload 
    loadbalance 
}

At the end rollout your CoreDNS to apply the changes.