snapshot-controller

snapshot-controller

Deploys the snapshot-controller and the snapshot-validation-webhook in a cluster. The controller is required for CSI snapshotting to work and is not specific to any CSI driver. The webhook is configured to validate every VolumeSnapshot and VolumeSnapshotContent resource by sending it to the validation webhook.

While many Kubernetes distributions already package this controller, some do not. If your cluster does NOT have the following CRDs, you likely also do not have a snapshot controller deployed:

kubectl get crd volumesnapshotclasses.snapshot.storage.k8s.io
kubectl get crd volumesnapshots.snapshot.storage.k8s.io
kubectl get crd volumesnapshotcontents.snapshot.storage.k8s.io

Usage

The snapshot-controller should be deployed together with the snapshot-validation-webhook which can be done by this simple Helm commands. See below for available configuration options.

helm repo add piraeus-charts https://piraeus.io/helm-charts/
helm install snapshot-controller piraeus-charts/snapshot-controller

Upgrades

Upgrades can be done using the normal Helm upgrade mechanism

helm repo update
helm upgrade snapshot-controller piraeus-charts/snapshot-controller

To enjoy all the latest features of the snapshot controller, you may want to upgrade your CRDs as well:

kubectl replace -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/v5.0.0/client/config/crd/snapshot.storage.k8s.io_volumesnapshotclasses.yaml
kubectl replace -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/v5.0.0/client/config/crd/snapshot.storage.k8s.io_volumesnapshots.yaml
kubectl replace -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/v5.0.0/client/config/crd/snapshot.storage.k8s.io_volumesnapshotcontents.yaml

Upgrade from older CRDs

In an effort to tighten validation, the CSI project started enforcing stricter requirements on VolumeSnapshot and VolumeSnapshotContent resources when switching from v1beta1 to v1 CRDs. This validation webhook is part of enforcing these requirements. When upgrading you have to ensure non of your resources violate the requirements for v1.

The upgrade procedure can be summarized by the following steps:

1. Remove the old snapshot controller, if any (since you are upgrading, you probably already have one deployed manually).

2. Install the snapshot controller and the validation webhook using one of the 3.x.x releases:

   helm install piraeus-charts/snapshot-controller --set controller.image.tag=v3.0.3 --set webhook.image.tag=v3.0.3
   

3. Ensure that none of the resources are labelled as invalid:

   kubectl get volumesnapshots --selector=snapshot.storage.kubernetes.io/invalid-snapshot-resource="" --all-namespaces
   kubectl get volumesnapshotcontents --selector=snapshot.storage.kubernetes.io/invalid-snapshot-resource="" --all-namespaces
   

   If the above commands output any resource, they have to be removed

4. Upgrade the CRDs

   kubectl replace -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/v5.0.0/client/config/crd/snapshot.storage.k8s.io_volumesnapshotclasses.yaml
   kubectl replace -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/v5.0.0/client/config/crd/snapshot.storage.k8s.io_volumesnapshots.yaml
   kubectl replace -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/v5.0.0/client/config/crd/snapshot.storage.k8s.io_volumesnapshotcontents.yaml
   

5. Upgrade to the latest version:

   helm upgrade piraeus-charts/snapshot-controller --set controller.image.tag=v5.0.0 --set webhook.image.tag=v5.0.0
   

Configuration

Snapshot controller

The following options are available:

Option	Usage	Default
controller.enabled	Toggle to disable the deployment of the snapshot controller.	true
controller.fullnameOverride	Set the base name of deployed resources. Defaults to snapshot-controller.	""
controller.args	Arguments to pass to the snapshot controller. Note: Keys will be converted to kebab-case, i.e. oneArg -> --one-arg	...
controller.replicaCount	Number of replicas to deploy.	1
controller.revisionHistoryLimit	Number of revisions to keep.	10
controller.image.repository	Repository to pull the image from.	registry.k8s.io/sig-storage/snapshot-controller
controller.image.pullPolicy	Pull policy to use. Possible values: IfNotPresent, Always, Never	IfNotPresent
controller.image.tag	Override the tag to pull. If not given, defaults to charts AppVersion.	""
controller.imagePullSecrets	Image pull secrets to add to the deployment.	[]
controller.podAnnotations	Annotations to add to every pod in the deployment.	{}
controller.podLabels	Labels to add to every pod in the deployment.	{}
controller.podSecurityContext	Security context to set on the webhook pod.	{}
controller.priorityClassName	Priority Class to set on the deployment pods.	""
controller.securityContext	Configure container security context. Defaults to dropping all capabilties and running as user 1000.	{capabilities: {drop: [ALL]}, readOnlyRootFilesystem: true, runAsNonRoot: true, runAsUser: 1000}
controller.resources	Resources to request and limit on the pod.	{}
controller.nodeSelector	Node selector to add to each webhook pod.	{}
controller.tolerations	Tolerations to add to each webhook pod.	[]
controller.topologySpreadConstraints	Topology spread constraints to set on each pod.	[]
controller.affinity	Affinity to set on each webhook pod.	{}
controller.pdb	PodDisruptionBudget to set on the webhook pod.	{}
controller.rbac.create	Create the necessary roles and bindings for the snapshot controller.	true
controller.serviceAccount.create	Create the service account resource	true
controller.serviceAccount.name	Sets the name of the service account. If left empty, will use the release name as default	""
controller.hostNetwork	Change hostNetwork to true when you want the pod to share its host's network namespace.	false
controller.dnsConfig	DNS settings for controller pod.	{}
controller.dnsPolicy	DNS Policy for controller pod. For Pods running with hostNetwork, set to ClusterFirstWithHostNet.	ClusterFirst

Snapshot Validation Webhook

Webhooks in Kubernetes are required to run on HTTPS. To that end, this charts needs to be configured with one of the following options:

• An auto-generated certificate, valid for 10 years. This is the default. If you want to renew the certificate, set webhook.tls.renew to true and run an upgrade.

• A cert-manager.io issuer able to create a certificate for the webhook service.

  To use this method, create an override file like:

  webhook:
    tls:
      certManagerIssuerRef:
        name: internal-issuer
        kind: ClusterIssuer

  To apply the override, use --values <override-file>.

• A pre-existing [kubernetes.io/tls] secret and the certificate of the CA used to sign said tls secret.

  To use this method, set --set webhook.tls.certificateSecret=<secretname>. The secret must be in the same namespace as the deployment and be valid for <release-name>.<namespace>.svc.

NOTE: When using a custom CNI (such as Weave or Calico) on Amazon EKS, the webhook cannot be reached.

Internal error occurred: failed calling webhook "snapshot-validation-webhook.snapshot.storage.k8s.io": failed to call webhook: Post "https://snapshot-validation-webhook.kube-system.svc:443/volumesnapshot?timeout=2s": Address is not allowed

This happens because the control plane cannot be configured to run on a custom CNI on EKS, so the CNIs differ between control plane and worker nodes.

To address this, the webhook can be run in the host network so it can be reached.

webhook:
  hostNetwork: true
  dnsPolicy: ClusterFirstWithHostNet

There are additional options that allow customization outside of HTTPS concerns. This is the full list of options available.

Option	Usage	Default
webhook.enabled	Toggle to disable the deployment of the snapshot validation webhook.	true
webhook.fullnameOverride	Set the base name of deployed resources. Defaults to snapshot-validation-webhook.	""
webhook.args	Arguments to pass to the snapshot controller. Note: Keys will be converted to kebab-case, i.e. oneArg -> --one-arg	...
webhook.replicaCount	Number of replicas to deploy.	1
webhook.revisionHistoryLimit	Number of revisions to keep.	10
webhook.image.repository	Repository to pull the image from.	registry.k8s.io/sig-storage/snapshot-validation-webhook
webhook.image.pullPolicy	Pull policy to use. Possible values: IfNotPresent, Always, Never	IfNotPresent
webhook.image.tag	Override the tag to pull. If not given, defaults to charts AppVersion.	""
webhook.webhook.timeoutSeconds	Timeout to use when contacting webhook server.	2
webhook.webhook.failurePolicy	Policy to apply when webhook is unavailable. Possible values: Fail, Ignore.	Fail
webhook.tls.certificateSecret	Name of the static tls secret to use for serving the HTTPS endpoint.	""
webhook.tls.autogenerate	Automatically generate the TLS secret for serving the HTTPS endpoint.	true
webhook.tls.renew	Force renewal of certificate when auto-generating.	false
webhook.tls.certManagerIssuerRef	Issuer to use for provisioning the TLS certificate. If this is used, tls.certificateSecret can be left empty.	{}
webhook.imagePullSecrets	Image pull secrets to add to the deployment.	[]
webhook.podAnnotations	Annotations to add to every pod in the deployment.	{}
webhook.podLabels	Labels to add to every pod in the deployment.	{}
webhook.networkPolicy.enabled	Should a network policy be created.	false
webhook.networkPolicy.ingress	Additional ingress rules to be added to the network policy.	{}
webhook.podDisruptionBudget.enabled	Should a pod disruption budget be created.	false
webhook.podDisruptionBudget.maxUnavailable	The maximum number of pods that are allowed to be unavailable.	""
webhook.podDisruptionBudget.minAvailable	The minimum number of pods that are required to be available.	""
webhook.priorityClassName	The name of the priority class to assign to the deployment.	""
webhook.topologySpreadConstraints	A list of topology constraints to assign to the deployment.	[]
webhook.podSecurityContext	Security context to set on the webhook pod.	{}
webhook.securityContext	Configure container security context. Defaults to dropping all capabilties and running as user 1000.	{capabilities: {drop: [ALL]}, readOnlyRootFilesystem: true, runAsNonRoot: true, runAsUser: 1000}
webhook.resources	Resources to request and limit on the pod.	{}
webhook.nodeSelector	Node selector to add to each webhook pod.	{}
webhook.tolerations	Tolerations to add to each webhook pod.	[]
webhook.affinity	Affinity to set on each webhook pod.	{}
webhook.serviceAccount.create	Create the service account resource	true
webhook.serviceAccount.name	Sets the name of the service account. If left empty, will use the release name as default	""
webhook.tests.nodeSelector	Node selector to add to each helm test pod.	{}
webhook.tests.tolerations	Tolerations to add to each helm test pod.	[]
webhook.tests.affinity	Affinity to set on each helm test pod.	{}
webhook.hostNetwork	Change hostNetwork to true when you want the pod to share its host's network namespace.	false
webhook.dnsConfig	DNS settings for webhook pod.	{}
webhook.dnsPolicy	DNS Policy for webhook pod. For Pods running with hostNetwork, set to ClusterFirstWithHostNet	ClusterFirst