Day 33/40

Kubernetes Ingress Tutorial | Ingress Explained by ‪@AbhishekVeeramalla‬

Video Link
@piyushsachdeva
Git Repository
My Git Repo

In this part, we are going to learn about Ingress in Kubernetes cluster.

In Kubernetes, Ingress is a resource type similar to Service, that allows you to easily route HTTP and HTTPS traffic entering the cluster through a single entry point to different services inside the cluster.
Traffic routing is defined by rules specified on the Ingress resource.

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A Kubernetes cluster can have multiple associated Ingress controllers, and each one works similarly to a deployment controller.
It is event-driven and gets triggered when, for example, a user creates, updates or deletes an Ingress.
Once triggered, an Ingress controller tracks a cluster’s Ingress resources and reads the Ingress specifications.
Then, it makes the configuration (in YAML or JSON) intelligible for the reverse proxy so it can provide the cluster with the resources it requires.

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• Benefits of Kubernetes Ingress:
  1. Load Balancing: Ingress can distribute traffic across multiple replicas of a service, ensuring high availability and scalability.
  2. SSL/TLS Termination: Ingress controllers can handle SSL/TLS termination, offloading the encryption/decryption workload from the application services.
  3. Name-based Virtual Hosting: Ingress allows multiple services to be exposed on the same IP address, using different hostnames.
  4. Path-based Routing: Ingress can route traffic to different services based on the URL path, simplifying the management of complex applications.
  5. Canary Deployments: Ingress can be used to implement canary deployments, gradually routing traffic to a new version of a service for testing purposes.

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Why ingress?

Before having ingress service, we review some disadvantages of a Load-Balancer services:
1. It's cloud-provider dependent.
2. It's costly and expensive affair and approach.
3. Security; we don't too much control of Load-Balancer service and we have to use everything the cloud provider decides.
So this is where Ingress comes to picture, when we need a load-balancer, an API, a DDOS protection, some white-listed addresses, a WAF and so on.

• There are some terms we need to understand: > 1. Ingress resource - is a standard configuration object for an ingress controller. > 2. Ingress controller - is a configurable proxy running in the cluster that is typically composed of a control plane and a data plane. > 3. Load balancer - a cloud provider creates a load balancer in front of the nodes. Clients can access applications via the IP of the load balancer.

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Note the Load-Balancing companies such as Nginx, develops a Kubernetes Ingress-Controller that when it would be deployed through Helm-Chart or a manifest, read a yaml file.

Note the Kubernetes Service can provides load-balancing but with basic features such as Round robin load balancing. But we know there are lots of enterprise technologies that we might need.

Note we need to create a ingress-resource that ingress-controller will watch and create and configure load-balancer based on it.

• Some ingress-controller for Kubernetes: > 1. Emissary > 2. Nginx > 3. HAProxy > 4. Enovy > 5. Traefik > 6. F5 Container > 7. Contour

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Demo

1. Clone files from repository

Repository

root@sinaops:/opt/Flask# tree .
.
├── Dockerfile
├── app.py
├── k8s
│   ├── deployment.yaml
│   ├── ingress.yaml
│   └── service.yaml
└── requirements.txt

1 directory, 6 files

2. Build the image and push to my repository

root@sinaops:/opt/Flask# docker build -t sinatavakkol/my-ingress-demo:v1 .

root@sinaops:/opt/Flask# docker images
REPOSITORY                                             TAG           IMAGE ID       CREATED          SIZE
sinatavakkol/my-ingress-demo                           v1            21794fe19661   19 seconds ago   137MB
...

root@sinaops:/opt/Flask# docker push sinatavakkol/my-ingress-demo:v1
The push refers to repository [docker.io/sinatavakkol/my-ingress-demo]
c15e83a40dc3: Pushed
e99cb889ac18: Pushed
34b40c4769c3: Pushed
d56439f47b97: Pushed
b8594deafbe5: Mounted from library/python
8a55150afecc: Mounted from library/python
ad34ffec41dd: Mounted from library/python
f19cb1e4112d: Mounted from library/python
d310e774110a: Mounted from library/python
v1: digest: sha256:e337d05667d7f0370268bff90dea054d49079a02f5be7196a9b74c237fd2e770 size: 2202

3. Replace the right image name for deployment file in k8s directory

root@sinaops:/opt/Flask# vim k8s/deployment.yaml

Line 19

4. Apply the deployment and service manifests

root@sinaops:/opt/Flask# kubectl apply -f k8s/deployment.yaml
deployment.apps/hello-world created
root@sinaops:~# kubectl get deploy -o wide
NAME          READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS    IMAGES                            SELECTOR
hello-world   1/1     1            1           17m   hello-world   sinatavakkol/my-ingress-demo:v1   app=hello-world
root@sinaops:/opt/Flask# kubectl apply -f k8s/service.yaml
service/hello-world created
root@sinaops:/opt/Flask# kubectl get svc
NAME          TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)   AGE
hello-world   ClusterIP   10.110.58.148   <none>        80/TCP    11s
kubernetes    ClusterIP   10.96.0.1       <none>        443/TCP   8d

• Test the service:

root@sinaops:/opt/Flask# curl 10.110.58.148
Hello, World!

5. The ingress resource

Based on the rule on the resource, if someone who go for example.com, followed by /, he reached to hello-world app followed by port: 80.

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: hello-world
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  ingressClassName: nginx
  rules:
  - host: "example.com"
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: hello-world
            port:
              number: 80

root@sinaops:/opt/Flask# kubectl apply -f  k8s/ingress.yaml
ingress.networking.k8s.io/hello-world created
root@sinaops:/opt/Flask# kubectl get ingress
NAME          CLASS   HOSTS         ADDRESS   PORTS   AGE
hello-world   nginx   example.com             80      25s

As we can see, there's not any address assigned because nobody is watching this resource!
So we need an Ingress-Controller.
Let's use nginx ingress controller.

6. Ingress Controller

There are 2 types of nginx ingress controller, one is for Kubernetes community and one is for Nginx developer:

Ingress-NGINX Controller vs NGINX Ingress Controller.

source

It continues on aws cloud ... I have no access to it

Nginx Contoller

(From the video)

• Because the cloud controller manager doesn't exist in this Kubernetes cluster:

• We edit ingress-contoller from loadBalancer type to nodePort so it will work:

• Delete ingress-resource and create it again:

• Because we told the load-balancer just route when domain name won't get ip-address, we should to edit /etc/hosts by nodePort IP address.