<p>I have attempted to follow <a href="https://crondev.com/kubernetes-nginx-ingress-controller/" rel="nofollow noreferrer">this</a> tutorial to play around with an nginx ingress controller. Some details have changed as I was trying to get it to work - only one backend service instead of two, some port numbers and everything runs in the default namespace. I have a kubernetes master and 3 minions on CentOS Linux release 7.4.1708 VMs.</p>

<p>The backend and default backend are both accessible within the cluster through their respective service endpoints.
The nginx status page is available externally (MasterHostIP:32000/nginx_status).
The issue is that http requests to the backend app are refused either through the external path or from within the cluster to the nginx-ingress-controller-service endpoints.
Hopefully someone out there can see something obvious that I'm missing, or has had similar issues and knows how to overcome this.</p>

<pre><code>[root@master1 ~]# kubectl get endpoints
NAME              ENDPOINTS                                         AGE
appsvc1           10.244.1.2:80,10.244.3.4:80                       3h
default-backend   10.244.1.3:8080,10.244.2.3:8080,10.244.3.5:8080   14d
kubernetes        10.134.45.136:6443                                15d
nginx-ingress     10.244.2.5:18080,10.244.2.5:9999                  2h
[root@master1 ~]# wget 10.244.2.5:9999
--2018-01-05 12:10:56--  http://10.244.2.5:9999/
Connecting to 10.244.2.5:9999... failed: Connection refused.
[root@master1 ~]# wget 10.244.2.5:18080
--2018-01-05 12:12:52--  http://10.244.2.5:18080/
Connecting to 10.244.2.5:18080... connected.
HTTP request sent, awaiting response... 404 Not Found
2018-01-05 12:12:52 ERROR 404: Not Found.
</code></pre>

<p>Requests to appsvc1 endpoints behave as expected, returning static html with "Hello app1!".</p>

<p><strong>Backend app deployment:</strong></p>

<pre><code>apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: app1
spec:
  replicas: 2
  template:
    metadata:
      labels:
        app: app1
    spec:
      containers:
      - name: app1
        image: dockersamples/static-site
        env:
        - name: AUTHOR
          value: app1
        ports:
        - containerPort: 80
</code></pre>

<p><strong>Backend Service</strong></p>

<pre><code>apiVersion: v1
kind: Service
metadata:
  name: appsvc1
spec:
  ports:
  - port: 9999
    protocol: TCP
    targetPort: 80
  selector:
    app: app1
</code></pre>

<p><strong>Application Ingress</strong></p>

<pre><code>apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  annotations:
    ingress.kubernetes.io/rewrite-target: /
  name: app-ingress
spec:
  rules:
  - host: test.com
    http:
      paths:
      - backend:
          serviceName: appsvc1
          servicePort: 9999
        path: /app1
</code></pre>

<p><strong>nginx ingress controller deployment</strong></p>

<pre><code>apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: nginx-ingress-controller
  annotations:
    kubernetes.io/ingress.class: "nginx"
spec:
  replicas: 1
  revisionHistoryLimit: 3
  template:
    metadata:
      labels:
        app: nginx-ingress-lb
    spec:
      terminationGracePeriodSeconds: 60
      serviceAccount: nginx
      containers:
      - name: nginx-ingress-controller
        image: quay.io/kubernetes-ingress-controller/nginx-ingress-controller:0.9.0
        imagePullPolicy: Always
        readinessProbe:
          httpGet:
            path: /healthz
            port: 10254
            scheme: HTTP
        livenessProbe:
          httpGet:
            path: /healthz
            port: 10254
            scheme: HTTP
          initialDelaySeconds: 10
          timeoutSeconds: 5
        args:
          - /nginx-ingress-controller
          - '--default-backend-service=$(POD_NAMESPACE)/default-backend'
          - '--configmap=$(POD_NAMESPACE)/nginx-ingress-controller-conf'
          - --v=6
        env:
          - name: POD_NAME
            valueFrom:
              fieldRef:
                fieldPath: metadata.name
          - name: POD_NAMESPACE
            valueFrom:
              fieldRef:
                fieldPath: metadata.namespace
        ports:
          - containerPort: 80
          - containerPort: 9999
          - containerPort: 18080
</code></pre>

<p><strong>nginx-ingress-controller-service</strong></p>

<pre><code>apiVersion: v1
kind: Service
metadata:
  name: nginx-ingress
spec:
  type: NodePort
  ports:
    - port: 9999
      nodePort: 30000
      name: http
    - port: 18080
      nodePort: 32000
      name: http-mgmt
  selector:
    app: nginx-ingress-lb
</code></pre>

<p><strong>nginx ingress</strong></p>

<pre><code>apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: nginx-ingress
  annotations:
    ingress.kubernetes.io/rewrite-target: /
spec:
  rules:
  - host: test.com
    http:
      paths:
      - backend:
          serviceName: nginx-ingress
          servicePort: 18080
</code></pre>

<p><strong>Update</strong>
It looks like port 9999 is not open in the ingress controller pod. Can anyone suggest why port 18080 gets opened but not 9999? :</p>

<pre><code>[root@master1 ~]# kubectl get pods
NAME                                       READY     STATUS    RESTARTS   AGE
app1-54cf69ff86-l7kp4                      1/1       Running   0          17d
app1-54cf69ff86-qkksw                      1/1       Running   0          17d
app2-7bc7498cbf-459vd                      1/1       Running   0          2d
app2-7bc7498cbf-8x9st                      1/1       Running   0          2d
default-backend-78484f94cf-fv6v4           1/1       Running   0          17d
default-backend-78484f94cf-vzp8l           1/1       Running   0          17d
default-backend-78484f94cf-wmjqh           1/1       Running   0          17d
nginx-ingress-controller-cfb567f76-wbck5   1/1       Running   0          15h
[root@master1 ~]# kubectl exec  nginx-ingress-controller-cfb567f76-wbck5 -it bash
root@nginx-ingress-controller-cfb567f76-wbck5:/# netstat -tlp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 0.0.0.0:http            0.0.0.0:*               LISTEN      14/nginx: master pr
tcp        0      0 0.0.0.0:http            0.0.0.0:*               LISTEN      14/nginx: master pr
tcp        0      0 0.0.0.0:https           0.0.0.0:*               LISTEN      14/nginx: master pr
tcp        0      0 0.0.0.0:https           0.0.0.0:*               LISTEN      14/nginx: master pr
tcp        0      0 0.0.0.0:18080           0.0.0.0:*               LISTEN      14/nginx: master pr
tcp        0      0 0.0.0.0:18080           0.0.0.0:*               LISTEN      14/nginx: master pr
tcp6       0      0 [::]:http               [::]:*                  LISTEN      14/nginx: master pr
tcp6       0      0 [::]:http               [::]:*                  LISTEN      14/nginx: master pr
tcp6       0      0 [::]:https              [::]:*                  LISTEN      14/nginx: master pr
tcp6       0      0 [::]:https              [::]:*                  LISTEN      14/nginx: master pr
tcp6       0      0 [::]:18080              [::]:*                  LISTEN      14/nginx: master pr
tcp6       0      0 [::]:18080              [::]:*                  LISTEN      14/nginx: master pr
tcp6       0      0 [::]:10254              [::]:*                  LISTEN      5/nginx-ingress-con
</code></pre>

<p>10.x adresses are internal. So the 404s are expected. The ingress controller doesn't make your internal services external all of a sudden. The ingress service is supposed to proxy requests to deployed services via a single address. Since I see you deployed the controller via node port, try making a request to the node's IP port 30000 with Host header test.com you should get your app. Every service you externalize will be available via the ingress IP, host header is set by HTTP clients and ingress controller will fan out requests based on that (as well as path and whatever else you want). So really it only works if you pay for domain names, as I assume you don't own test.com and asking users to fake the request header is not a reasonable interface</p>

<p>Also, since you have minion nodes (plural) you should really change the controller service type from NodePort to LoadBalancer. Node port is used in tutorials so as to be cheaper - LoadBalancer will spin up a cloud load balancer that you would have to pay for. Node port is OK while you're getting situated but certainly not something you can do later on. I really wish people would stop putting it in tutorials without any explanations</p>
