How-to: Enable the Placement Operator NetworkPolicy

This guide walks an operator through opting in to the chart-level NetworkPolicy that restricts the placement-operator pod's egress and ingress to the minimum required for correct reconciliation.

Scope. This guide covers the NetworkPolicy that protects the operator pod itself. For the per-CR NetworkPolicy that protects the Placement API pods (spec.networkPolicy on a Placement CR), see the Placement CRD API Reference. That per-CR policy restricts ingress to TCP 8778 from the sources you list (at least one is required, so an empty list is refused) and derives its egress from the CR: DNS, the database, the Keystone endpoint's port, and the cache, with additionalEgress appended after it.

---

Prerequisites

Devstack

This guide is written against the Quick Start (ControlPlane) devstack. Stand it up first:

KIND_HOST_PORT=8443 WITH_CONTROLPLANE=true make deploy-infra

Follow that tutorial through to its final Verify step, so the placement-operator is running (namespace placement-system) alongside the projected controlplane-placement resource-tracking service.

1. A CNI that enforces networking.k8s.io/v1 NetworkPolicy (required for real enforcement). Confirm with your platform team (Calico, Cilium, and Antrea enforce).

   Enforcement cannot be verified on the default devstack CNI

   The ControlPlane Quick Start kind devstack uses the default kindnet CNI, which silently ignores NetworkPolicy objects, and kind fixes the CNI at cluster creation so it cannot be swapped in afterwards. The policy object is still created and the operator keeps reconciling, so Step 2 below confirms only the policy's shape and that enabling it does not break reconciliation. It does not prove that packets outside the allow-list are dropped. Real enforcement requires a cluster whose CNI enforces NetworkPolicy, typically your production platform.

2. A running placement-operator Helm release (namespace placement-system).

3. The ControlPlane declares spec.services.placement. Without it no controlplane-placement child exists and the Step 2 verification has nothing to roll.

Step 1 — Enable the policy

The chart guards networkPolicy.enabled=true with a fail-closed check: networkPolicy.kubeApiServer.cidrs and ports must both be non-empty, or the template refuses to render. Gather the API server CIDRs and ports from the kubernetes Endpoints — the real API server addresses, not the 10.96.0.1 Service VIP that kubectl get service kubernetes reports. An enforcing CNI (Calico, Cilium) DNATs a packet aimed at the VIP to one of those endpoint IPs before it evaluates policy, so a rule naming the VIP never matches:

kubectl get endpoints kubernetes -n default -o json \
  | jq -r '.subsets[] | (.addresses[].ip) as $ip | (.ports[].port) as $p | "\($ip)/32 port=\($p)"'

Record every endpoint IP the command prints, not just the first. A kind devstack reports the one control-plane node's address on the kind bridge (172.18.0.x), but an HA control plane reports one per API server replica:

10.0.0.10/32 port=6443
10.0.0.11/32 port=6443
10.0.0.12/32 port=6443

The rule must cover all of them, or the operator loses its leader-election lease whenever it happens to be talking to an excluded replica.

On the tutorial devstacks the placement-operator release is owned by Flux (a HelmRelease), so set the values by patching its spec.values, not with a raw helm upgrade, which the Flux helm-controller reverts on its next reconcile. Substitute the CIDRs and ports from above. The single-CIDR list below stands in for the kind case — one control-plane node — so replace 172.18.0.2/32 with the address you recorded and extend the list to every IP an HA control plane prints:

kubectl patch helmrelease placement-operator -n placement-system --type=merge \
  -p '{"spec":{"values":{"networkPolicy":{"enabled":true,"kubeApiServer":{"cidrs":["172.18.0.2/32"],"ports":[6443]}}}}}'

kubectl wait helmrelease/placement-operator -n placement-system \
  --for=condition=Ready --timeout=5m

The chart-level policy allows what the operator needs: egress to the kube-apiserver and DNS, ingress to the webhook and metrics ports. The placement-operator's health check reaches the Placement Service on TCP 8778 in the workload namespace; when the workload namespace itself runs a per-CR NetworkPolicy, the operator's namespace is admitted automatically by the sub-reconciler (an operator-namespace ingress peer is appended to every rendered policy).

Metrics ingress is opt-in and separate. networkPolicy.allowMetricsFrom is empty by default, and with the policy on, an empty list means no ingress rule for the metrics port at all, so a Prometheus that scraped the operator before stops reaching it. Name the scraping namespace when you enable both this policy and the ServiceMonitor from Enable the Placement Operator Metrics Endpoint:

kubectl patch helmrelease placement-operator -n placement-system --type=merge \
  -p '{"spec":{"values":{"networkPolicy":{"allowMetricsFrom":[{"namespaceSelector":{"matchLabels":{"kubernetes.io/metadata.name":"monitoring"}}}]}}}}'

Each entry is rendered verbatim as a NetworkPolicyPeer, so a podSelector narrows it further to the Prometheus pods.

Helm-managed installations (non-Flux)

If you installed the operator directly with Helm (not through Flux), set the values with a rolling helm upgrade. The fail-closed guard still requires kubeApiServer.cidrs and ports:

helm upgrade placement-operator oci://ghcr.io/c5c3/charts/placement-operator \
  --namespace placement-system --reuse-values \
  --set networkPolicy.enabled=true \
  --set 'networkPolicy.kubeApiServer.cidrs[0]=172.18.0.2/32' \
  --set 'networkPolicy.kubeApiServer.ports[0]=6443'

Do not run this on the tutorial devstacks: there the release is Flux-owned, and the helm-controller reverts out-of-band revisions on its next reconcile. Use the HelmRelease patch above instead.

Step 2 — Verify

On the kind devstack this verifies the policy's shape and that enabling it does not break reconciliation, not traffic enforcement, which the default kindnet CNI does not apply (see the prerequisite above).

kubectl -n placement-system get networkpolicy
kubectl -n placement-system describe networkpolicy placement-operator

Then confirm reconciliation still works end-to-end by driving a change through the ControlPlane CR and watching the projected resource-tracking service roll out:

kubectl patch controlplane controlplane -n openstack --type merge \
  -p '{"spec":{"services":{"placement":{"replicas":2}}}}'
kubectl rollout status deploy/controlplane-placement -n openstack

# revert
kubectl patch controlplane controlplane -n openstack --type merge \
  -p '{"spec":{"services":{"placement":{"replicas":1}}}}'

Set the replica count on the ControlPlane CR, not on the projected controlplane-placement child: the c5c3-operator re-asserts the child's spec.deployment.replicas on every reconcile, so a direct edit of the child is reverted.

Troubleshooting

Reconcile timeouts / leader-election churn

Symptom: operator logs show Get https://<kube-apiserver>: i/o timeout or leader-election lease renewals fail with context deadline exceeded, and the placement-operator pod restarts.

Diagnosis: the egress allow-list does not match the API server the operator actually dials. Either kubeApiServer.cidrs is missing one or more of the current endpoint IPs — an HA control plane may have added a replica, or a control-plane node may have been replaced with a different IP — or your CNI maps the API server behind a port that is not in kubeApiServer.ports.

Fix: re-run the discovery command from Step 1 and update networkPolicy.kubeApiServer.cidrs to include every IP it returns, plus every port:

kubectl get endpoints kubernetes -n default -o json \
  | jq -r '.subsets[] | (.addresses[].ip) as $ip | (.ports[].port) as $p | "\($ip)/32 port=\($p)"'

Every Placement write is rejected

Symptom: kubectl apply on a Placement CR fails with failed calling webhook plus connection refused or no route to host. The ControlPlane stalls too: the c5c3-operator projects controlplane-placement through the same admission path, so its reconcile fails on the same error.

Diagnosis: webhook ingress (9443) is blocked. Both placement webhooks register failurePolicy=Fail on create and update, so an unreachable operator turns into a cluster-wide rejection of every write to the kind. The usual cause is an API server that calls webhooks from an IP that is not in endpoints/kubernetes, for example because it sits behind a front-end proxy. networkPolicy.webhookClients.cidrs falls back to kubeApiServer.cidrs when empty, which is wrong in that topology.

Fix: discover the actual caller IP (check the API-server audit log or the kube-apiserver Pod's --advertise-address) and set networkPolicy.webhookClients.cidrs explicitly:

kubectl patch helmrelease placement-operator -n placement-system --type=merge \
  -p '{"spec":{"values":{"networkPolicy":{"webhookClients":{"cidrs":["10.1.0.0/24"]}}}}}'

If the wedge blocks you from recovering, set networkPolicy.enabled=false with the same patch shape. The policy object is removed on the next reconcile and the operator reverts to unrestricted pod networking without a pod restart.

Tested by

Every operator chart carries an equivalent chart-level NetworkPolicy template (each chart ships its own copy, not a shared operator-library helper). The keystone chart's copy is exercised end-to-end on the CI e2e kind cluster by the chainsaw suite below; the placement chart's copy is pinned by its helm-unittest (operators/placement/helm/placement-operator/tests/networkpolicy_test.yaml).

chainsaw test --test-dir tests/e2e/keystone-operator/network-policy-egress