Configuration Validation Problems

Seemingly valid configuration is rejected

Manually verify your configuration is correct, cross-referencing Istio API reference when necessary.

Invalid configuration is accepted

Verify the istiod-istio-system validationwebhookconfiguration exists and is correct. The apiVersion, apiGroup, and resource of the invalid configuration should be listed in one of the two webhooks entries.

$ kubectl get validatingwebhookconfiguration istiod-istio-system -o yaml
apiVersion: admissionregistration.k8s.io/v1
kind: ValidatingWebhookConfiguration
metadata:
  creationTimestamp: "2020-01-24T19:53:03Z"
  generation: 1
  labels:
    app: istiod
    istio: istiod
    release: istio
  name: istiod-istio-system
  ownerReferences:
  - apiVersion: rbac.authorization.k8s.io/v1
    blockOwnerDeletion: true
    controller: true
    kind: ClusterRole
    name: istiod-istio-system
    uid: c3d24917-c2da-49ad-add3-c91c14608a45
  resourceVersion: "36649"
  selfLink: /apis/admissionregistration.k8s.io/v1/validatingwebhookconfigurations/istiod-istio-system
  uid: 043e39d9-377a-4a67-a7cf-7ae4cb3c562c
webhooks:
- admissionReviewVersions:
  - v1beta1
  clientConfig:
    # caBundle should be non-empty. This is periodically (re)patched
    # every second by the webhook service using the ca-cert
    # from the mounted service account secret.
    caBundle: LS0t...
    service:
      # service corresponds to the Kubernetes service that implements the
      # webhook, e.g. istio-galley.istio-system.svc:443
      name: istiod
      namespace: istio-system
      path: /validate
      port: 443
  failurePolicy: Fail
  matchPolicy: Exact
  name: validation.istio.io
  namespaceSelector: {}
  objectSelector: {}
  rules:
  - apiGroups:
    - config.istio.io
    - rbac.istio.io
    - security.istio.io
    - authentication.istio.io
    - networking.istio.io
    apiVersions:
    - '*'
    operations:
    - CREATE
    - UPDATE
    resources:
    - '*'
    scope: '*'
  sideEffects: None
  timeoutSeconds: 30

If the validatingwebhookconfiguration doesn’t exist, verify the istio-validation configmap exists. Istio uses the data from this configmap to create and update the validatingwebhookconfiguration.

$ kubectl -n istio-system get configmap istio-validation -o jsonpath='{.data}'
map[config:apiVersion: admissionregistration.k8s.io/v1beta1
kind: ValidatingWebhookConfiguration
metadata:
  name: istiod-istio-system
  namespace: istio-system
  labels:
    app: istiod
    release: istio
    istio: istiod
webhooks:
  - name: validation.istio.io
    clientConfig:
      service:
        name: istiod
        namespace: istio-system
        path: "/validate"
        port: 443
      caBundle: ""
    rules:
      - operations:
        - CREATE
        - UPDATE
        apiGroups:
        - config.istio.io
        - rbac.istio.io
        - security.istio.io
        - authentication.istio.io
        - networking.istio.io
        apiVersions:
        - "*"
        resources:
        - "*"
    failurePolicy: Fail
    sideEffects: None]
      (... snip ...)

If the webhook array in istio-validation is empty, verify the global.configValidation installation options are set.

The validation configuration is fail-close. If configuration exists and is scoped properly, the webhook will be invoked. A missing caBundle, bad certificate, or network connectivity problem will produce an error message when the resource is created/updated. If you don’t see any error message and the webhook wasn’t invoked and the webhook configuration is valid, your cluster is misconfigured.

Creating configuration fails with x509 certificate errors

x509: certificate signed by unknown authority related errors are typically caused by an empty caBundle in the webhook configuration. Verify that it is not empty (see verify webhook configuration). Istio consciously reconciles webhook configuration used the istio-validation configmap and root certificate.

1. Verify the istiod pod(s) are running:

   $  kubectl -n istio-system get pod -lapp=istiod
   NAME                            READY     STATUS    RESTARTS   AGE
   istiod-5dbbbdb746-d676g   1/1       Running   0          2d
   

2. Check the pod logs for errors. Failing to patch the caBundle should print an error.

   $ for pod in $(kubectl -n istio-system get pod -lapp=istiod -o jsonpath='{.items[*].metadata.name}'); do \
       kubectl -n istio-system logs ${pod} \
   done
   

3. If the patching failed, verify the RBAC configuration for Istiod:

   $ kubectl get clusterrole istiod-istio-system -o yaml
   apiVersion: rbac.authorization.k8s.io/v1
   kind: ClusterRole
     name: istiod-istio-system
   rules:
   - apiGroups:
     - admissionregistration.k8s.io
     resources:
     - validatingwebhookconfigurations
     verbs:
     - '*'
   

   Istio needs validatingwebhookconfigurations write access to create and update the validatingwebhookconfiguration.

Creating configuration fails with no such hosts or no endpoints available errors

Validation is fail-close. If the istiod pod is not ready, configuration cannot be created and updated. In such cases you’ll see an error about no endpoints available.

Verify the istiod pod(s) are running and endpoints are ready.

$  kubectl -n istio-system get pod -lapp=istiod
NAME                            READY     STATUS    RESTARTS   AGE
istiod-5dbbbdb746-d676g   1/1       Running   0          2d

$ kubectl -n istio-system get endpoints istiod
NAME           ENDPOINTS                          AGE
istiod         10.48.6.108:15014,10.48.6.108:443   3d

If the pods or endpoints aren’t ready, check the pod logs and status for any indication about why the webhook pod is failing to start and serve traffic.

$ for pod in $(kubectl -n istio-system get pod -lapp=istiod -o jsonpath='{.items[*].metadata.name}'); do \
    kubectl -n istio-system logs ${pod} \
done

$ for pod in $(kubectl -n istio-system get pod -lapp=istiod -o name); do \
    kubectl -n istio-system describe ${pod} \
done