Migrate to Cilium CNI

Prerequisites

cluster-admin privileges
kubectl
jq
curl
Working commodore command

Prepare for migration

Make sure that your $KUBECONFIG points to the cluster you want to migrate before starting.

Create alertmanager silence

silence_id=$(
    kubectl --as=cluster-admin -n openshift-monitoring exec \
    sts/alertmanager-main -- amtool --alertmanager.url=http://localhost:9093 \
    silence add alertname!=Watchdog --duration="3h" -c "cilium migration"
)
echo $silence_id

Select cluster

export CLUSTER_ID=c-cluster-id-1234 (1)
export COMMODORE_API_URL=https://api.syn.vshn.net (2)
export TENANT_ID=$(curl -sH "Authorization: Bearer $(commodore fetch-token)" \
  "${COMMODORE_API_URL}/clusters/${CLUSTER_ID}" | jq -r '.tenant')

1	Replace with the Project Syn cluster ID of the cluster to migrate
2	Replace with the Lieutenant API on which the cluster is registered

Disable ArgoCD auto sync for components openshift4-nodes and openshift-upgrade-controller

kubectl --as=cluster-admin -n syn patch apps root --type=json \
  -p '[{"op":"replace", "path":"/spec/syncPolicy", "value": {}}]'
kubectl --as=cluster-admin -n syn patch apps openshift4-nodes --type=json \
  -p '[{"op":"replace", "path":"/spec/syncPolicy", "value": {}}]'
kubectl --as=cluster-admin -n syn patch apps openshift-upgrade-controller --type=json \
  -p '[{"op":"replace", "path":"/spec/syncPolicy", "value": {}}]'

Disable the cluster-network-operator. This is necessary to ensure that we can migrate to Cilium without the cluster-network-operator trying to interfere. We also need to scale down the upgrade controller, so that we can patch the ClusterVersion object.

kubectl --as=cluster-admin -n appuio-openshift-upgrade-controller \
  scale deployment openshift-upgrade-controller-controller-manager --replicas=0

kubectl --as=cluster-admin patch clusterversion version \
  --type=merge \
  -p '
  {"spec":{"overrides":[
    {
      "kind": "Deployment",
      "group": "apps",
      "name": "network-operator",
      "namespace": "openshift-network-operator",
      "unmanaged": true
    }
  ]}}'

kubectl --as=cluster-admin -n openshift-network-operator \
  scale deploy network-operator --replicas=0

Verify that the network operator has been scaled down.

kubectl -n openshift-network-operator get pods (1)

1	This should return `No resources found in openshift-network-operator namespace`.

If the operator is still running, check the following conditions:

The APPUiO OpenShift upgrade controller must be scaled down.
The ClusterVersion object must have an override to make the network operator deployment unmanaged.

Remove network operator applied state

kubectl --as=cluster-admin -n openshift-network-operator \
  delete configmap applied-cluster

Pause all machine config pools

for mcp in $(kubectl get mcp -o name); do
kubectl --as=cluster-admin patch $mcp --type=merge -p '{"spec": {"paused": true}}'
done

Migrate to Cilium

Get local cluster working directory
```
commodore catalog compile "$CLUSTER_ID" (1)
```
1 We recommend switching to an empty directory to run this command. Alternatively, switch to your existing directory for the cluster.

Enable component cilium

pushd inventory/classes/"${TENANT_ID}"
yq -i '.applications += "cilium"' "${CLUSTER_ID}.yml"

Update upstreamRules for monitoring

yq -i ".parameters.openshift4_monitoring.upstreamRules.networkPlugin = \"cilium\"" \
  "${CLUSTER_ID}.yml"

Update component networkpolicy config

yq eval -i '.parameters.networkpolicy.networkPlugin = "cilium"' \
  "${CLUSTER_ID}.yml"
yq eval -i '.parameters.networkpolicy.ignoredNamespaces = ["openshift-oauth-apiserver"]' \
  "${CLUSTER_ID}.yml"

Verify that the cluster’s api-int DNS record exists

export CLUSTER_DOMAIN=$(kubectl get dns cluster -ojsonpath='{.spec.baseDomain}')
kubectl --as=cluster-admin -n openshift-dns exec ds/node-resolver -- nslookup api-int.${CLUSTER_DOMAIN}

If the command doesn’t return a valid record for api-int, the Cilium config needs to be adjusted to use the api record to ensure that the Kubernetes API can be accessed.

yq -i '.parameters.cilium.cilium_helm_values.k8sServiceHost="api.${openshift:baseDomain}"' \
  "${CLUSTER_ID}.yml"

Configure component cilium.

Configure the cluster Pod and Service CIDRs

POD_CIDR=$(kubectl get network.config cluster \
  -o jsonpath='{.spec.clusterNetwork[0].cidr}')
HOST_PREFIX=$(kubectl get network.config cluster \
  -o jsonpath='{.spec.clusterNetwork[0].hostPrefix}')

yq -i '.parameters.cilium.cilium_helm_values.ipam.operator.clusterPoolIPv4MaskSize = "'"${HOST_PREFIX}"'"' \
  "${CLUSTER_ID}.yml"
yq -i '.parameters.cilium.cilium_helm_values.ipam.operator.~clusterPoolIPv4PodCIDRList = "'"${POD_CIDR}"'"' \
  "${CLUSTER_ID}.yml"

Commit changes

git commit -am "Migrate ${CLUSTER_ID} to Cilium"
git push origin master
popd

Compile catalog

commodore catalog compile "${CLUSTER_ID}"

Patch cluster network config

Only execute this step after you’ve paused all machine config pools. Otherwise, nodes may reboot into a state where they’re stuck in NotReady.

kubectl --as=cluster-admin patch network.config cluster \
  --type=merge -p '{"spec":{"networkType":"Cilium"},"status":null}'
kubectl --as=cluster-admin patch network.operator cluster \
  --type=merge -p '{"spec":{"defaultNetwork":{"type":"Cilium"}},"status":null}'

Apply Cilium manifests. We need to execute the apply twice, since the first apply will fail to create the CiliumConfig resource.

kubectl --as=cluster-admin apply -n cilium -Rf catalog/manifests/cilium/

kubectl --as=cluster-admin apply -n cilium -Rf catalog/manifests/cilium/

Wait until Cilium CNI is up and running
```
kubectl -n cilium get pods -w
```

Finalize migration

Re-enable cluster network operator

This will remove the previously active CNI plugin and will deploy the kube-proxy daemonset. As soon as you complete this step, existing pods may go into CrashLoopBackOff since they were started with CNI IPs managed by the old network plugin.

kubectl --as=cluster-admin -n openshift-network-operator \
  scale deployment network-operator --replicas=1
kubectl --as=cluster-admin patch clusterversion version \
 --type=merge -p '{"spec":{"overrides":null}}'

Unpause MCPs

for mcp in $(kubectl get mcp -o name); do
kubectl --as=cluster-admin patch $mcp --type=merge -p '{"spec":{"paused":false}}'
done

You may need to grab the cluster-admin credentials to complete this step since the OpenShift OAuth components may be unavailable until they’re restarted with Cilium-managed IPs.

You may want to restart the multus daemonset once the old CNI pods are removed.

kubectl --as=cluster-admin -n openshift-multus rollout restart ds/multus

It may be necessary to force drain nodes manually to allow the machine-config-operator to reboot the nodes. Use kubectl --as=cluster-admin drain --ignore-daemonsets --delete-emptydir-data --force --disable-eviction to circumvent PDB violations if necessary.

Start with a master node, and ensure that the machine-config-operator is running on that master node after it’s been drained and rebooted.

Compile and push catalog

commodore catalog compile "${CLUSTER_ID}" --push

Re-enable ArgoCD auto sync

kubectl --as=cluster-admin -n syn patch apps root --type=json \
  -p '[{
    "op":"replace",
    "path":"/spec/syncPolicy",
    "value": {"automated": {"prune": true, "selfHeal": true}}
  }]'

Cleanup alert silence

Expire alertmanager silence

kubectl --as=cluster-admin -n openshift-monitoring exec sts/alertmanager-main --\
    amtool --alertmanager.url=http://localhost:9093 silence expire $silence_id