K
Q

How can I ensure ingress controller pods are running on each of the nodes that contain the pods for it's backend services?

6/9/2021

I've setup the ingress-nginx Helm chart to setup ingress controllers on my cluster, however by default it only runs a single pod instance.

Since we're running on Digital Ocean's k8s cluster, we're running with externalTrafficPolicy: Local to allow cert-manager to access other pods internally, and also so we have less network hops for requests.

For resilience we've configured our backend services to run on at least 2 nodes, so it makes sense that we have ingress controllers on each of the nodes that have a backend pod running on it, to avoid unnecessary inter-node traffic.

How would we go about configuring the ingress controller setup to ensure that we have a controller pod on each of the nodes that the backend pods are running on?

-- TobyG
kubernetes
kubernetes-ingress
nginx-ingress

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1 Answer

6/9/2021

If you want to run the POD on each node you can use the daemonset.

Deamon set : https://github.com/nginxinc/kubernetes-ingress/blob/master/deployments/helm-chart/templates/controller-daemonset.yaml

now if you want to make sure Nginx ingress controller POD only run on Nodes on which your backend service running, you can use affinity and anti-affinity.

Affinity example :

affinity:
    nodeAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
        nodeSelectorTerms:
          - matchExpressions:
            - key: role
              operator: In
              values:
              - app-1
    podAntiAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
        - labelSelector:
            matchExpressions:
              - key: component
                operator: In
                values:
                - nginx-ms
          topologyKey: "kubernetes.io/1-hostname"

You can read more and find example at : https://github.com/infracloudio/kubernetes-scheduling-examples/blob/master/podAffinity/README.md

-- Harsh Manvar
Source: StackOverflow