How to Manage External Traffic with Kubernetes Ingress

Introduction

This tutorial provides a comprehensive understanding of Kubernetes Ingress, a powerful feature that simplifies service exposure and management. You will learn how to configure Ingress annotations and settings, as well as apply Ingress in real-world scenarios to optimize your Kubernetes infrastructure.

Skills Graph

Understanding Kubernetes Ingress

Kubernetes Ingress is a powerful feature that provides advanced routing and load balancing capabilities for your Kubernetes services. It acts as a gateway, managing external access to your internal services, and allows you to configure sophisticated routing rules based on various criteria, such as URL paths, hostnames, and HTTP headers.

At its core, the Ingress resource in Kubernetes is responsible for defining the rules that govern how external traffic is routed to your internal services. It works in conjunction with an Ingress controller, which is a specialized Kubernetes component that implements the Ingress rules and manages the underlying load balancing infrastructure.

One of the primary benefits of Kubernetes Ingress is its ability to simplify service exposure and management. Instead of exposing each individual service directly to the internet, you can use Ingress to consolidate and manage all external traffic through a single entry point. This not only reduces the complexity of your infrastructure but also provides additional features, such as SSL/TLS termination, URL-based routing, and load balancing.

Kubernetes Ingress can be particularly useful in scenarios where you have multiple services that need to be exposed to the internet, or when you want to provide a unified entry point for your application. By leveraging Ingress, you can easily manage and configure routing rules, load balancing, and SSL/TLS termination, all from a single resource.

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 the example above, the Ingress resource defines two routing rules: one for the /api path that routes traffic to the api-service, and another for the /web path that routes traffic to the web-service. This allows you to expose multiple services through a single Ingress entry point, simplifying the management and configuration of your Kubernetes application.

Configuring Ingress Annotations and Settings

Kubernetes Ingress provides a wide range of annotations and settings that allow you to customize and fine-tune the behavior of your Ingress resources. These annotations and settings can be used to configure various aspects of the Ingress, such as load balancing, SSL/TLS termination, and routing rules.

One common use case for Ingress annotations is to configure load balancing. For example, you can use the nginx.ingress.kubernetes.io/load-balance annotation to specify the load balancing algorithm, such as round-robin or least-conn:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: example-ingress
  annotations:
    nginx.ingress.kubernetes.io/load-balance: round-robin
spec:
  ## ...

Another useful annotation is nginx.ingress.kubernetes.io/ssl-redirect, which can be used to automatically redirect HTTP traffic to HTTPS:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: example-ingress
  annotations:
    nginx.ingress.kubernetes.io/ssl-redirect: "true"
spec:
  ## ...

Ingress also supports the use of TLS/SSL certificates. You can configure the Ingress to terminate SSL/TLS traffic using the tls field in the Ingress specification:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: example-ingress
spec:
  tls:
  - hosts:
    - example.com
    secretName: tls-secret
  ## ...

In the example above, the Ingress is configured to terminate SSL/TLS traffic for the example.com host, using the TLS secret stored in the tls-secret Kubernetes secret.

Ingress also provides a wide range of other annotations and settings, such as:

By leveraging these annotations and settings, you can create highly customized and sophisticated Ingress configurations to meet the specific requirements of your Kubernetes application.

Applying Ingress in Real-World Scenarios

Kubernetes Ingress can be applied to a wide range of real-world scenarios, helping to simplify service management and improve the overall user experience. Let's explore a few examples of how Ingress can be leveraged in practice.

Multi-Tenant Application Deployment

In a multi-tenant environment, where multiple applications or teams share the same Kubernetes cluster, Ingress can be used to provide a unified entry point and routing mechanism. By configuring Ingress rules based on hostname or URL path, you can route traffic to the appropriate services, ensuring that each tenant's application is isolated and secure.

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: multi-tenant-ingress
spec:
  rules:
  - host: tenant1.example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: tenant1-service
            port:
              number: 80
  - host: tenant2.example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: tenant2-service
            port:
              number: 80

Blue-Green Deployments

Ingress can also be used to facilitate blue-green deployments, a popular strategy for rolling out application updates with minimal downtime. By configuring Ingress to route traffic to different service versions based on specific criteria (e.g., HTTP headers, URL parameters), you can seamlessly switch between the old and new versions of your application without disrupting user access.

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: blue-green-ingress
spec:
  rules:
  - http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: blue-service
            port:
              number: 80
        ## Use a custom header to route traffic to the "green" version
        nginx.ingress.kubernetes.io/service-match: 'green: header("X-Version", "green")'
      - path: /
        pathType: Prefix
        backend:
          service:
            name: green-service
            port:
              number: 80
        nginx.ingress.kubernetes.io/service-match: 'blue: header("X-Version", "blue")'

Canary Deployments

Ingress can also be leveraged for canary deployments, a strategy that allows you to gradually roll out changes to a small subset of users before making the changes available to the entire user base. By configuring Ingress to route a percentage of traffic to the new version of your application, you can monitor its performance and user feedback before fully committing to the update.

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: canary-ingress
spec:
  rules:
  - http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: stable-service
            port:
              number: 80
        ## Route 10% of traffic to the canary version
        nginx.ingress.kubernetes.io/canary: "true"
        nginx.ingress.kubernetes.io/canary-weight: "10"
      - path: /
        pathType: Prefix
        backend:
          service:
            name: canary-service
            port:
              number: 80
        nginx.ingress.kubernetes.io/canary: "true"

These are just a few examples of how Kubernetes Ingress can be applied in real-world scenarios. By leveraging the flexibility and customization options provided by Ingress, you can create sophisticated routing and traffic management solutions to meet the unique requirements of your Kubernetes-based applications.

Summary

Kubernetes Ingress is a crucial component that enables advanced routing and load balancing for your services. By leveraging Ingress, you can consolidate and manage all external traffic through a single entry point, simplifying your infrastructure and providing additional features like SSL/TLS termination, URL-based routing, and load balancing. This tutorial has equipped you with the knowledge to configure Ingress annotations and settings, as well as apply Ingress in various real-world scenarios, empowering you to optimize the performance and security of your Kubernetes applications.