How to get traefik ingress to load balance across several ClusterIP services

Question

I want to be able to load balance several nodes of a backend service represented by ClusterIP services using a traefik.containo.us/v1alpha1 ingress. I know that ClusterIP service can load balance easily with deployments and ReplicaSet but the way this application is designed each node needs to be it's own Deployment as it is a stateful node.

So I either need a way to have the flow be:

Ingress --> [ClusterIP-Node1, ClusterIP-Node2, ClusterIP-Node3, ClusterIP-Node4]

or

Ingress --> ClusterIP-LoadBalancer --> [ClusterIP-Node1, ClusterIP-Node2, ClusterIP-Node3, ClusterIP-Node4]

How can I use traefik.containo.us/v1alpha1 to automatically loadbalance between these ClusterIP services?

For example, if I currently have one Ingress for each `ClusterIP, like this:

...
apiVersion: traefik.containo.us/v1alpha1
kind: IngressRoute
metadata:
  name: my-service-node1-ingress
spec:
  entryPoints:
    - web
    - websecure
  routes:
    - kind: Rule
      match: Host(`myservice-node1.mycompany.example`)
      services:
        - kind: Service
          name: myservice-node1-clusterip
          passHostHeader: true
          port: 80

apiVersion: v1
kind: Service
metadata:
  name: myservice-node1-clusterip
  labels:
    app: myservice
    tier: backend
    name: myservice-node1
spec:
  selector:
    app: myservice
    tier: backend
    name: myservice-node1-deployment
  type: ClusterIP
  ports:
    - name: rpc-listener
      protocol: TCP
      port: 80
      targetPort: 8545
... N+1

And I want to change that to a single Ingress Point similar to this:

apiVersion: traefik.containo.us/v1alpha1
kind: IngressRoute
metadata:
  name: my-service-ingress
spec:
  entryPoints:
    - web
    - websecure
  routes:
    - kind: Rule
      match: Host(`myservice.mycompany.example`)
      services:
        - kind: Service
          name: myservice-node1-clusterip
          passHostHeader: true
          port: 80

Is it possible to have the traefik.containo.us/v1alpha1 load balance across the services similar to this? I saw something that looked promising on this page in the docs that you can have n number of services[n].name for a matching route routes[n].services. Does that mean you can do something similar to the following?

apiVersion: traefik.containo.us/v1alpha1
kind: IngressRoute
metadata:
  name: my-service-ingress
spec:
  entryPoints:
    - web
    - websecure
  routes:
    - kind: Rule
      match: Host(`myservice.mycompany.example`)
      services:
        - kind: Service
          name: myservice-node1-clusterip
          passHostHeader: true
          port: 80
        - kind: Service
          name: myservice-node2-clusterip
          passHostHeader: true
          port: 80
        - kind: Service
          name: myservice-node3-clusterip
          passHostHeader: true
          port: 80
        - kind: Service
          name: myservice-node4-clusterip
          passHostHeader: true
          port: 80

Also, is there a way to pass the sessionAffinity with it like there are in services sessionAffinity: ClientIP?

score 1 · Accepted Answer · answered May 16 '21 at 20:10

The sample I posted initially works as is:

apiVersion: traefik.containo.us/v1alpha1
kind: IngressRoute
metadata:
  name: my-service-ingress
spec:
  entryPoints:
    - web
    - websecure
  routes:
    - kind: Rule
      match: Host(`myservice.mycompany.example`)
      services:
        - kind: Service
          name: myservice-node1-clusterip
          passHostHeader: true
          port: 80
        - kind: Service
          name: myservice-node2-clusterip
          passHostHeader: true
          port: 80
        - kind: Service
          name: myservice-node3-clusterip
          passHostHeader: true
          port: 80
        - kind: Service
          name: myservice-node4-clusterip
          passHostHeader: true
          port: 80

How to get traefik ingress to load balance across several ClusterIP services

1 Answers1