Getting Started with Kubernetes Ingress: Rewrite Path

Getting Started with Kubernetes Ingress: Rewrite Path

Kubernetes, the open-source platform for automating deployment, scaling, and management of containerized applications, has become a staple in the world of DevOps and data science. One of its powerful features is the Ingress, which manages external access to services within a cluster. In this blog post, we will delve into the specifics of Kubernetes Ingress and how to rewrite paths.

What is Kubernetes Ingress?

Before we dive into the details, let’s first understand what Kubernetes Ingress is. Ingress, in the Kubernetes ecosystem, is an API object that manages external access to the services in a cluster, typically HTTP. Ingress can provide load balancing, SSL termination, and name-based virtual hosting.

Why Rewrite Path?

Rewriting paths in Ingress allows you to modify the URL path in an HTTP request directed at your service before the request is forwarded to your application. This is particularly useful when you want to make your services available under a specific URL structure.

Prerequisites

Before we start, make sure you have the following:

• A Kubernetes cluster up and running.
• kubectl installed and configured to interact with your cluster.
• Basic understanding of Kubernetes concepts like Pods, Services, and Ingress.

Step 1: Deploy a Sample Application

First, let’s deploy a simple application to your cluster. We’ll use a basic HTTP server that serves a static page. Here’s a simple deployment configuration:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: http-server
spec:
  replicas: 3
  selector:
    matchLabels:
      app: http-server
  template:
    metadata:
      labels:
        app: http-server
    spec:
      containers:
      - name: http-server
        image: hashicorp/http-echo
        args:
        - "-text=Hello, Kubernetes!"
        ports:
        - containerPort: 5678

Apply this configuration using kubectl apply -f http-server.yaml.

Step 2: Create a Service

Next, we need to create a service to expose our application. Here’s a simple service configuration:

apiVersion: v1
kind: Service
metadata:
  name: http-server
spec:
  selector:
    app: http-server
  ports:
    - protocol: TCP
      port: 80
      targetPort: 5678

Apply this configuration using kubectl apply -f http-server-service.yaml.

Step 3: Configure Ingress to Rewrite Path

Now, let’s configure Ingress to rewrite the path. We’ll use the nginx.ingress.kubernetes.io/rewrite-target annotation to rewrite the path:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: http-server
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /$2
spec:
  rules:
  - host: myapp.mydomain.com
    http:
      paths:
      - pathType: Prefix
        path: /myapp(/|$)(.*)
        backend:
          service:
            name: http-server
            port:
              number: 80

In this configuration, any requests to myapp.mydomain.com/myapp will be rewritten to / before they are forwarded to the http-server service.

Apply this configuration using kubectl apply -f http-server-ingress.yaml.

Conclusion

Kubernetes Ingress provides a flexible way to control the traffic routing to your services. By rewriting paths, you can ensure that your services are accessible under the desired URL structure. This is just one of the many powerful features of Kubernetes Ingress, and understanding it can greatly enhance your ability to manage and control service access in a Kubernetes environment.

Remember, the key to mastering Kubernetes is practice and experimentation. So, don’t hesitate to tweak the configurations and see what works best for your specific use case.

Keywords

• Kubernetes
• Ingress
• Rewrite Path
• Load Balancing
• SSL Termination
• Virtual Hosting
• HTTP Server
• Deployment
• Service
• Traffic Routing
• DevOps
• Data Science

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