How to route traffic with Ingress

Introduction

This tutorial will guide you through understanding Kubernetes Ingress, configuring Ingress routing and traffic management, and implementing Ingress in your Kubernetes clusters. Kubernetes Ingress is a powerful feature that simplifies the management of external access to services within a Kubernetes cluster, acting as a layer 7 load balancer and providing a unified entry point for inbound traffic.

Skills Graph

Understanding Kubernetes Ingress

Kubernetes Ingress is a powerful feature that simplifies the management of external access to services within a Kubernetes cluster. It acts as a layer 7 load balancer, providing a unified entry point for inbound traffic and handling routing, load balancing, and SSL/TLS termination.

The Ingress resource in Kubernetes defines rules for routing incoming HTTP and HTTPS traffic to different services within the cluster. This allows you to expose multiple services through a single IP address or hostname, without the need to configure a separate load balancer for each service.

The Ingress controller is a Kubernetes component responsible for implementing the Ingress resource. It watches the Kubernetes API for Ingress resource updates and configures the underlying load balancing infrastructure accordingly. There are several Ingress controller implementations available, such as NGINX Ingress Controller, Traefik, and Istio Ingress Gateway.

Using Kubernetes Ingress offers several benefits:

1. Simplified Routing: Ingress provides a unified entry point for managing external access to services within the cluster, reducing the complexity of configuring individual services.
2. Load Balancing: Ingress controllers handle load balancing, distributing incoming traffic across multiple service replicas.
3. SSL/TLS Termination: Ingress can be configured to terminate SSL/TLS connections, offloading the encryption/decryption process from the services.
4. Centralized Access Control: Ingress allows you to apply security policies, such as authentication and authorization, at the entry point, simplifying access management.

To use Kubernetes Ingress, you need to define an Ingress resource that specifies the rules for routing traffic to your services. Here's an example Ingress configuration:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: example-ingress
spec:
  rules:
  - host: example.com
    http:
      paths:
      - path: /api
        pathType: Prefix
        backend:
          service:
            name: api-service
            port:
              number: 80
      - path: /web
        pathType: Prefix
        backend:
          service:
            name: web-service
            port:
              number: 80

In this example, the Ingress resource routes traffic to two different services: api-service and web-service, based on the incoming URL path. Traffic to example.com/api is forwarded to the api-service, while traffic to example.com/web is forwarded to the web-service.

Configuring Ingress Routing and Traffic Management

Kubernetes Ingress provides flexible routing capabilities to manage incoming traffic to your services. Ingress supports two main types of routing: path-based routing and host-based routing.

Path-based Routing:
Path-based routing allows you to route traffic to different services based on the incoming URL path. This is useful when you have multiple services exposed under different URL paths within the same domain. Here's an example Ingress configuration for path-based routing:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: example-ingress
spec:
  rules:
  - http:
      paths:
      - path: /api
        pathType: Prefix
        backend:
          service:
            name: api-service
            port:
              number: 80
      - path: /web
        pathType: Prefix
        backend:
          service:
            name: web-service
            port:
              number: 80

Host-based Routing:
Host-based routing allows you to route traffic to different services based on the incoming hostname. This is useful when you have multiple domains or subdomains pointing to your Kubernetes cluster. Here's an example Ingress configuration for host-based routing:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: example-ingress
spec:
  rules:
  - host: api.example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: api-service
            port:
              number: 80
  - host: web.example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: web-service
            port:
              number: 80

In addition to routing, Ingress can also handle SSL/TLS termination, offloading the encryption/decryption process from your services. This is done by configuring TLS settings in the Ingress resource:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: example-ingress
spec:
  tls:
  - hosts:
    - example.com
    secretName: tls-secret
  rules:
  - host: example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: web-service
            port:
              number: 80

In this example, the Ingress resource is configured to terminate SSL/TLS connections using a TLS secret named tls-secret. The tls-secret should contain the TLS certificate and private key.

By leveraging Ingress routing and traffic management capabilities, you can simplify the exposure of your Kubernetes services and apply advanced routing and security policies at the entry point of your cluster.

Implementing Ingress in Kubernetes Clusters

Implementing Ingress in a Kubernetes cluster involves several steps, including installing an Ingress controller, creating Ingress resources, and configuring related resources.

Installing an Ingress Controller:
Kubernetes does not provide a default Ingress controller. You need to install and configure an Ingress controller implementation, such as NGINX Ingress Controller, Traefik, or Istio Ingress Gateway. The installation process varies depending on the Ingress controller you choose. For example, to install the NGINX Ingress Controller on a Kubernetes cluster running on Ubuntu 22.04, you can use the following commands:

## Add the Ingress controller repository
sudo apt-get update
sudo apt-get install -y apt-transport-https ca-certificates curl
sudo curl -fsSLo /usr/share/keyrings/nginx-ingress-controller.gpg 
echo "deb [signed-by=/usr/share/keyrings/nginx-ingress-controller.gpg]  jammy nginx" | sudo tee /etc/apt/sources.list.d/nginx-ingress-controller.list
sudo apt-get update

## Install the NGINX Ingress Controller
sudo apt-get install -y nginx-ingress-controller

Creating Ingress Resources:
Once the Ingress controller is installed, you can create Ingress resources to define the routing rules for your services. Here's an example Ingress configuration:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: example-ingress
spec:
  rules:
  - host: example.com
    http:
      paths:
      - path: /api
        pathType: Prefix
        backend:
          service:
            name: api-service
            port:
              number: 80
      - path: /web
        pathType: Prefix
        backend:
          service:
            name: web-service
            port:
              number: 80

This Ingress resource routes traffic to the api-service and web-service based on the incoming URL path.

Configuring Related Resources:
In addition to the Ingress resource, you may need to configure other Kubernetes resources, such as Services, Deployments, and Secrets (for SSL/TLS termination), to ensure the proper functioning of your Ingress setup.

Troubleshooting Ingress:
If you encounter issues with your Ingress implementation, you can use the following techniques to troubleshoot:

1. Check the Ingress controller logs for any error messages or warnings.
2. Verify the Ingress resource configuration, ensuring that the paths, service names, and ports are correct.
3. Ensure that the underlying Services and Deployments are correctly configured and accessible.
4. Check the Kubernetes events for any relevant information about the Ingress resource.
5. Use tools like kubectl describe ingress and kubectl get ingress -o yaml to inspect the Ingress resource and its status.

By following best practices and troubleshooting techniques, you can effectively implement Ingress in your Kubernetes clusters to manage external access to your services.

Summary

In this tutorial, you have learned about the key benefits of using Kubernetes Ingress, including simplified routing, load balancing, SSL/TLS termination, and centralized access control. You have also seen how to define an Ingress resource to configure routing rules and manage external access to your services within a Kubernetes cluster. By understanding and leveraging Kubernetes Ingress, you can streamline the management of your application's traffic and improve the overall user experience.