title: How to update ngnix configuration of ngnix ingress controller
body: <p>I have installed <code>ngnix</code> ingress controller on <code>K8 cluster</code> using helm chart.</p>
  
  <pre><code>helm install --name nginx-ingress stable/nginx-ingress --namespace kube-system
  </code></pre>
  
  <p>I want to update below values in <code>ngnix.conf</code> file of <code>ngnix</code> ingress controller:</p>
  
  <pre><code> 1. proxy-connect-timeout
   2. proxy-read-timeout
   3. location 
  
  {
      add_header "Cache-Control" "max-age=0, no-cache, no-store, must-revalidate";
      add_header "Pragma" "no-cache";
      add_header "Expires" "-1";
  }
  </code></pre>
  
  <p>I have used below ingress.yaml:</p>
  
  <pre><code>apiVersion: extensions/v1beta1
  kind: Ingress
  metadata:
    name: test-iningress
    annotations:
      nginx.ingress.kubernetes.io/rewrite-target: /
      nginx.ingress.kubernetes.io/proxy-connect-timeout: "300s"
      nginx.ingress.kubernetes.io/proxy-read-timeout: "300s"
      nginx.ingress.kubernetes.io/client-max-body-size: "0"
      nginx.ingress.kubernetes.io/server-snippet: |
                    location / {
                       add_header "Cache-Control" "max-age=0, no-cache, no-store, must-revalidate";
                       add_header "Pragma" "no-cache";
                       add_header "Expires" "-1";
                    }
  spec:
    rules:
    - host: {{ .Values.ingress.hosts }}
      http:
        paths:
        - path: /ui
          backend:
            serviceName: sift-ui-service
            servicePort: {{ .Values.service.sift_ui.port }}
  </code></pre>
  
  <p>Then when I check ngnix.conf using</p>
  
  <pre><code>kubectl exec -it nginx-ingress-controller-b4477bdf7-gwt8v -n kube-system -- cat /etc/nginx/nginx.conf
  </code></pre>
  
  <p><code>proxy-connect-timeout</code> and <code>proxy-read-timeout</code> do not get updated.  It shows default values, and server-snippet also not get added.</p>
  
  <p>Can anyone tell me how to <code>update/add</code> configuration of <code>ngnix</code> ingress controller?</p>