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Ingress

What is Ingress ?

Ingress exposes HTTP and HTTPS routes from outside the cluster to services within the cluster.

graph LR
    client[Client] --> lb[Ingress-managed Load Balancer]
    lb --> ingress[Ingress]
    ingress --> service[Service]
    service --> pod1[Pod]
    service --> pod2[Pod]

Prerequisites

You must have an Ingress controller to satisfy an Ingress. Only creating an Ingress resource has no effect.

Ingress Controllers List

  • AKS Application Gateway Ingress Controller
  • Apache APISIX ingress controller
  • Avi Kubernetes Operator
  • NGINX Ingress Controller for Kubernetes
  • And many many more

Hands On: Install Nginx Ingress

kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v1.12.3/deploy/static/provider/aws/deploy.yaml

kubectl get ns
# ingress-nginx    Active    12s

kubectl get all -n ingress-nginx

NAME                                           READY   STATUS      RESTARTS   AGE
pod/ingress-nginx-admission-create-12345       0/1     Completed   0          23s
pod/ingress-nginx-admission-patch-12345        0/1     Completed   1          23s
pod/ingress-nginx-controller-69fbbf9f9c-h67pr  0/1     Running     0          23s
NAME                                        TYPE           CLUSTER-IP       EXTERNAL-IP                                                      PORT(S)                       AGE
service/ingress-nginx-controller            LoadBalancer   100.68.173.127   a07bff36074ee45d6a8ab27eb91b1f83-f.elb.us-west-2.amazonaws.com   80:32718/TCP, 443:32372/TCP   23s
service/ingress-nginx-controller-admission  ClusterIP      100.66.154.8     <none>                                                           443/TCP                       23s

NAME                                        READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/ingress-nginx-controller    1/1     1            1           23s

NAME                                                  DESIRED   CURRENT   READY   AGE
replicaset.apps/ingress-nginx-controller-69fbfbf9f9c  1         1         1    23s

NAME                                           COMPLETIONS   DURATION   AGE
job.batch/ingress-nginx-admission-create       1/1           3s         23s
job.batch/ingress-nginx-admission-patch        1/1           4s         23s

In this example the credentials are:

  • External DNS (Load Balancer):
    • a07bff36074ee45d6a8ab27eb91b1f83-f.elb.us-west-2.amazonaws.com
  • Internal IP (Load Balancer): 100.68.173.127
  • Internal IP (Cluster IP): 100.66.154.8
  • Ingress routing (following your defined rules):
    • pod/ingress-nginx-controller-69fbbf9f9c-h67pr
  • Deployment: deployment.apps/ingress-nginx-controller
  • Replica set: replicaset.apps/ingress-nginx-controller-69fbfbf9f9c
  • Jobs:
    • job.batch/ingress-nginx-admission-create
    • job.batch/ingress-nginx-admission-patch

This commands will create a loadbalancer in ROUTE 53 (AWS Cloud)

vim vprodep.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  selector:
    matchLabels:
      run: my-app
  replicas: 1
  template:
    metadata:
      labels:
        run: my-app
    spec:
      containers:
        - name: my-app
          image: imranvisualpath/vproappfix
          ports:
            - containerPort: 8080


vim vprosvc.yaml

apiVersion: v1
kind: Service
metadata:
  name: my-app
spec:
  ports:
    - port: 8080
      protocol: TCP
      targetPort: 8080
  selector:
    run: my-app
  type: ClusterIP

vim vproingress.yaml

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: vpro-ingress
  annotations:
    nginx.ingress.kubernetes.io/use-regex: "true"
spec:
  ingressClassName: nginx
  rules:
    - host: vprofile.alexanderlindholm.net
      http:
        paths:
          - path: /login
            pathType: Prefix
            backend:
              service:
                name: my-app
                port:
                  number: 8080

replace alexanderlindholm.net with your DNS name

kubectl apply -f vprodep.yaml

kubectl apply -f vprosvc.yaml

Create DNS CNAME before Applying vproingress.yaml

Visit your DNS provider, in my case it will be Namecheap

  1. Go to DNS records section (Advanced DNS for Namecheap)

  2. Apply this credentials:

    • TYPE: CNAME
    • Name: vprofile
    • Value: a07bff36074ee45d6a8ab27eb91b1f83-f.elb.us-west-2.amazonaws.com

Check if my-app service is running:

kubectl get svc
# my-app    ClusterIP    100.69.158.126    <none>    8080/TCP    120s
kubectl describe svc my-app

Keep in mind that we are creating Ingress rule for this ClusterIP Service

  1. Client makes an HTTP request to: http://vprofile.alexanderlindholm.net/login (This DNS name resolves to the External IP/DNS of the Ingress LoadBalancer.)
  2. The request hits the Ingress Controller (NGINX) via the LoadBalancer, which processes the request using the rules defined in your Ingress resource. It then forwards the request to the my-app Service (which is of type ClusterIP).
  3. The ClusterIP Service (my-app) routes the traffic to one of the backing Pods (using label selectors), and the application running in the pod responds.
graph LR
    client["Client (vprofile.alexanderlindholm.net/login)"] --> lb["LoadBalancer (Ingress Controller)"]
    lb --> ingress["Ingress Resource: /login"]
    ingress --> service["ClusterIP Service: my-app"]
    service --> pod["Pod: my-app"]
kubectl apply -f vproingress.yaml

kubectl get ingress
# vpro-ingress   nginx   vprofile.alexanderlindholm.net   a07bff36074ee45d6a8ab27eb91b1f83-f.elb.us-west-2.amazonaws.com

Visit page at: a07bff36074ee45d6a8ab27eb91b1f83-f.elb.us-west-2.amazonaws.com.

This URL would be different for you.

kubectl delete ingress vpro-ingress

Optional: Change app path to fix content rendering on the page

The page is not rendering becouse the routing is happening internally not in the app

vim vproingress.yaml
# change /login to /

kubectl apply -f vproingress.yaml && kubectl get ingress --watch

Delete

kubectl get ns
kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v1.12.3/deploy/static/provider/aws/deploy.yaml