Load balance traffic

The ingress controller load balances traffic across pods by reading Ingress resources, which group pods under Service resources. But, you can customize its behavior, such as to set a different load balancing algorithm.

Change the load balancing algorithm for a specific service Jump to heading #

By default, the ingress controller uses the round-robin algorithm to distribute requests across a service’s pods. To change the algorithm for a specific service:

1. Edit the Ingress resource and set the load-balance annotation to your chosen algorithm. Below, we set the service to use the random algorithm:

   example-ingress.yaml
   yaml
   apiVersion: networking.k8s.io/v1
   kind: Ingress
   metadata:
     name: example-ingress
     annotations:
       load-balance: random
   spec:
     ingressClassName: haproxy
     rules:
     - host: "example.com"
       http:
         paths:
         - path: /
           pathType: Prefix
           backend:
             service:
               name: example-service
               port:
                 number: 8080

   example-ingress.yaml
   yaml
   apiVersion: networking.k8s.io/v1
   kind: Ingress
   metadata:
     name: example-ingress
     annotations:
       load-balance: random
   spec:
     ingressClassName: haproxy
     rules:
     - host: "example.com"
       http:
         paths:
         - path: /
           pathType: Prefix
           backend:
             service:
               name: example-service
               port:
                 number: 8080

2. Apply the change with kubectl apply:

   nix
   kubectl apply -f example-ingress.yaml

   nix
   kubectl apply -f example-ingress.yaml

Enable sticky sessions (session persistence) Jump to heading #

In some cases, you may need to route all of a client’s requests to the same backend pod. For example, if that pod has stored the client’s server-side session, you would want to use that same pod, rather than load balance their requests across multiple pods. This is called sticky sessions. To enable it for a service:

1. In the Ingress resource, set the cookie-persistence annotation to a unique name, which the ingress controller uses when naming the HTTP cookie it stores in the client’s browser. The cookie will contain the selected pod’s IP address, port, and a secret key.

   example-ingress.yaml
   yaml
   apiVersion: networking.k8s.io/v1
   kind: Ingress
   metadata:
     name: example-ingress
     annotations:
       cookie-persistence: "example-session-persistence-cookie"
   spec:
     ingressClassName: haproxy
     rules:
     - host: "example.com"
       http:
         paths:
         - path: /
           pathType: Prefix
           backend:
             service:
               name: example-service
               port:
                 number: 8080

   example-ingress.yaml
   yaml
   apiVersion: networking.k8s.io/v1
   kind: Ingress
   metadata:
     name: example-ingress
     annotations:
       cookie-persistence: "example-session-persistence-cookie"
   spec:
     ingressClassName: haproxy
     rules:
     - host: "example.com"
       http:
         paths:
         - path: /
           pathType: Prefix
           backend:
             service:
               name: example-service
               port:
                 number: 8080

2. Apply the change with kubectl apply:

   nix
   kubectl apply -f example-ingress.yaml

   nix
   kubectl apply -f example-ingress.yaml