Node affinity of IPPool

Spiderpool supports affinity between IP pools and Nodes. It means only Pods running on these Nodes can use the IP pools that have an affinity to these Nodes.

Node affinity should be regarded as a filtering mechanism rather than a pool selection rule.

Set up Spiderpool

If you have not deployed Spiderpool yet, follow the guide installation for instructions on how to deploy and easily configure Spiderpool.

Get started

Since the cluster in this example has only two Nodes (1 master and 1 worker), it is required to remove the relevant taints on the master Node through kubectl taint, so that ordinary Pods can also be scheduled to it. If your cluster has two or more worker Nodes, please ignore the step above.

Create two IPPools with 1 IP address each, one of which will provide IP addresses for all Pods running on the master Node.

kubectl apply -f https://raw.githubusercontent.com/spidernet-io/spiderpool/main/docs/example/ippool-affinity-node/master-ipv4-ippool.yaml

apiVersion: spiderpool.spidernet.io/v2beta1
kind: SpiderIPPool
metadata:
  name: master-ipv4-ippool
spec:
  subnet: 172.18.41.0/24
  ips:
  - 172.18.41.40
  gateway: 172.18.41.1
  nodeAffinity:
    matchExpressions:
    - {key: node-role.kubernetes.io/master, operator: Exists}

The other provides IP addresses for the Pods on the worker Node.

kubectl apply -f https://raw.githubusercontent.com/spidernet-io/spiderpool/main/docs/example/ippool-affinity-node/worker-ipv4-ippool.yaml

apiVersion: spiderpool.spidernet.io/v2beta1
kind: SpiderIPPool
metadata:
  name: worker-ipv4-ippool
spec:
  subnet: 172.18.42.0/24
  ips:
  - 172.18.42.40
  gateway: 172.18.42.1
  nodeAffinity:
    matchExpressions:
    - {key: node-role.kubernetes.io/master, operator: DoesNotExist}

Here, the value of the Node annotation node-role.kubernetes.io/master distinguishes two Nodes with different roles (or different node regions). If there is no annotation node-role.kubernetes.io/master on your Nodes, you can change it to another one or add some annotations you want.

Then, create a Deployment with 2 replicas, and set podAntiAffinity to ensure that the two Pods which select the above IPPools according to the syntax of alternative IP pools can be scheduled to different Nodes.

kubectl apply -f https://raw.githubusercontent.com/spidernet-io/spiderpool/main/docs/example/ippool-affinity-node/node-affinity-deploy.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: node-affinity-deploy
spec:
  replicas: 2
  selector:
    matchLabels:
      app: node-affinity-deploy
  template:
    metadata:
      annotations:
        ipam.spidernet.io/ippool: |-
          {
            "ipv4": ["master-ipv4-ippool", "worker-ipv4-ippool"]
          }
      labels:
        app: node-affinity-deploy
    spec:
      affinity:
        podAntiAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
          - labelSelector:
              matchLabels:
                app: node-affinity-deploy
            topologyKey: kubernetes.io/hostname
      containers:
      - name: node-affinity-deploy
        image: busybox
        imagePullPolicy: IfNotPresent
        command: ["/bin/sh", "-c", "trap : TERM INT; sleep infinity & wait"]

Finally, you will find that Pods on different Nodes will use different IPPools.

kubectl get se
NAME                                    INTERFACE   IPV4POOL             IPV4              IPV6POOL   IPV6   NODE                   CREATETION TIME
node-affinity-deploy-66c9874465-rvdkm   eth0        master-ipv4-ippool   172.18.41.40/24                     spider-control-plane   35s
node-affinity-deploy-66c9874465-wb8ds   eth0        worker-ipv4-ippool   172.18.42.40/24                     spider-worker          35s

Clean up

Clean the relevant resources so that you can run this tutorial again.

kubectl delete \
-f https://raw.githubusercontent.com/spidernet-io/spiderpool/main/docs/example/ippool-affinity-node/master-ipv4-ippool.yaml \
-f https://raw.githubusercontent.com/spidernet-io/spiderpool/main/docs/example/ippool-affinity-node/worker-ipv4-ippool.yaml \
-f https://raw.githubusercontent.com/spidernet-io/spiderpool/main/docs/example/ippool-affinity-node/node-affinity-deploy.yaml \
--ignore-not-found=true