A Rancher-managed Nginx Ingress Controller is your gateway to exposing your Kubernetes services to the outside world, but getting it set up correctly can feel like navigating a maze.
Let’s see it in action. Imagine you have a simple web application running in a Kubernetes cluster managed by Rancher. You want to make it accessible via myapp.example.com.
First, you’ll need to ensure the ingress-nginx chart is deployed in your cluster. This is typically done via Rancher’s UI under the "Apps & Marketplace" section. You’ll select the ingress-nginx chart, choose the namespace where you want it installed (often ingress-nginx or kube-system), and then configure its values.
Here’s a peek at a typical values.yaml for the ingress-nginx chart:
controller:
replicaCount: 2
nodeSelector: {}
resources:
requests:
cpu: 100m
memory: 100Mi
service:
type: LoadBalancer
loadBalancerIP: 192.168.1.100 # This is crucial for static IPs
externalTrafficPolicy: Cluster
The service.type: LoadBalancer tells Kubernetes to provision an external load balancer. If you’re on a cloud provider, this will be a managed load balancer. On-premises, you might use MetalLB or a similar solution. The loadBalancerIP is key for ensuring your Ingress Controller always gets the same external IP address, which you’ll then point your DNS records to.
Once the chart is deployed and the Nginx Ingress Controller pods are running, you’ll create an Ingress resource in Kubernetes. This resource defines the rules for routing external HTTP(S) traffic to your internal services.
Here’s an example Ingress manifest:
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: myapp-ingress
namespace: default
annotations:
nginx.ingress.kubernetes.io/rewrite-target: /
spec:
ingressClassName: nginx # This should match your Ingress Controller's class
rules:
- host: myapp.example.com
http:
paths:
- path: /
pathType: Prefix
backend:
service:
name: myapp-service
port:
number: 80
This Ingress resource tells the Nginx Ingress Controller: "When a request comes in for myapp.example.com and the path starts with /, forward it to the myapp-service on port 80."
The ingressClassName: nginx annotation is vital. It tells Kubernetes which Ingress Controller should handle this Ingress resource. If you have multiple Ingress Controllers, this ensures the traffic goes to the right one.
The nginx.ingress.kubernetes.io/rewrite-target: / annotation is often used to strip a prefix from the URL before forwarding it to the backend service. In this case, if the external request was myapp.example.com/some/path, it would be rewritten to /some/path before being sent to myapp-service. If your service expects the root path, you’d use /.
The Nginx Ingress Controller itself is a highly configurable component. You can tweak its behavior through ConfigMaps, allowing you to set timeouts, buffer sizes, SSL settings, and much more. For example, to increase the client body buffer size, you might add an entry to your ingress-nginx controller’s ConfigMap:
apiVersion: v1
kind: ConfigMap
metadata:
name: ingress-nginx-controller
namespace: ingress-nginx # Or wherever your controller is installed
data:
client-body-buffer-size: "16m"
This allows larger file uploads or requests with bigger payloads to be processed correctly by the Ingress Controller.
The most surprising thing about how the Nginx Ingress Controller handles requests is that it doesn’t directly receive traffic from the internet. Instead, the Kubernetes Service of type LoadBalancer (or NodePort, or whatever you’ve configured) acts as the entry point. This Service then forwards traffic to the Nginx Ingress Controller pods. The Ingress Controller, in turn, watches for Ingress resources and dynamically configures its Nginx proxy based on those rules. It’s a layered approach, with each layer responsible for a specific part of the traffic routing puzzle.
When you’re dealing with SSL/TLS, you’ll typically create a Kubernetes Secret containing your certificate and private key, and then reference that Secret in your Ingress resource’s tls section.
# ... within your Ingress resource ...
spec:
ingressClassName: nginx
tls:
- hosts:
- myapp.example.com
secretName: myapp-tls-secret # This Secret must exist in the same namespace
rules:
- host: myapp.example.com
http:
paths:
# ... your paths ...
This tells the Nginx Ingress Controller to use the certificate from myapp-tls-secret for TLS termination for requests to myapp.example.com.
The next hurdle you’ll often encounter is configuring advanced routing rules, such as path-based routing with different backends or implementing canary deployments using traffic splitting annotations.