The CSI external-resizer
is a sidecar container that watches the Kubernetes API server for PersistentVolumeClaim
updates and
triggers ControllerExpandVolume
operations against a CSI endpoint if user requested more storage on PersistentVolumeClaim
object.
A storage provider that allows volume expansion after creation, may choose to implement volume expansion either via a
control-plane CSI RPC call or via node CSI RPC call or both as a two step process. The external-resizer is an external-controller that watches Kubernetes API server for PersistentVolumeClaim
modifications and triggers CSI calls for control-plane volume-expansion. More details can be found on - CSI Volume expansion
This information reflects the head of this branch.
Compatible with CSI Version | Container Image | Min K8s Version | Recommended K8s Version |
---|---|---|---|
CSI Spec v1.2.0 | k8s.gcr.io/sig-storage/csi-resizer | 1.16 | 1.16 |
Currently all CSI volume expansion features are supported as Beta features by external-resizer.
It is necessary to create a new service account and give it enough privileges to run the external-resizer, see deploy/kubernetes/rbac.yaml
. The resizer is then deployed as single Deployment as illustrated below:
kubectl create deploy/kubernetes/deployment.yaml
The external-resizer may run in the same pod with other external CSI controllers such as the external-attacher, external-snapshotter and/or external-provisioner.
Note that the external-resizer does not scale with more replicas. Only one external-resizer is elected as leader and running. The others are waiting for the leader to die. They re-elect a new active leader in ~15 seconds after death of the old leader.
-
--csi-address <path to CSI socket>
: This is the path to the CSI driver socket inside the pod that the external-resizer container will use to issue CSI operations (/run/csi/socket
is used by default). -
--leader-election
: Enables leader election. This is mandatory when there are multiple replicas of the same external-resizer running for one CSI driver. Only one of them may be active (=leader). A new leader will be re-elected when current leader dies or becomes unresponsive for ~15 seconds. -
--leader-election-namespace
: Namespace where the leader election resource lives. Defaults to the pod namespace if not set. -
--leader-election-lease-duration <duration>
: Duration, in seconds, that non-leader candidates will wait to force acquire leadership. Defaults to 15 seconds. -
--leader-election-renew-deadline <duration>
: Duration, in seconds, that the acting leader will retry refreshing leadership before giving up. Defaults to 10 seconds. -
--leader-election-retry-period <duration>
: Duration, in seconds, the LeaderElector clients should wait between tries of actions. Defaults to 5 seconds. -
--timeout <duration>
: Timeout of all calls to CSI driver. It should be set to value that accommodates majority ofControllerExpandVolume
calls. 10 seconds is used by default. -
-kube-api-burst <int>
: Burst to use while communicating with the kubernetes apiserver. Defaults to 10. (default 10). -
-kube-api-qps <float>
: QPS to use while communicating with the kubernetes apiserver. Defaults to 5.0. (default 5). -
--retry-interval-start
: The starting value of the exponential backoff for failures. 1 second is used by default. -
--retry-interval-max
: The exponential backoff maximum value. 5 minutes is used by default. -
--workers <num>
: Number of simultaneously runningControllerExpandVolume
operations. Default value is10
. -
--http-endpoint
: The TCP network address where the HTTP server for diagnostics, including metrics and leader election health check, will listen (example::8080
which corresponds to port 8080 on local host). The default is empty string, which means the server is disabled. -
--metrics-path
: The HTTP path where prometheus metrics will be exposed. Default is/metrics
. -
--handle-volume-inuse-error <true/false>
: Enable or disable volume-in-use error handling in external-resizer. Defaults totrue
and resize-controller will watch for all pods in all namespaces to check if PVC being expanded is in-use by a pod or not before retrying volume expansion if CSI driver throws volume-in-use error. Setting this tofalse
will cause external-resizer to ignore volume-in-use error and resize-controller will retry volume expansion even if volume is already in use by a pod and CSI driver does not support expansion of in-use volumes. If CSI driver being used supports online expansion, it might be desirable to sethandle-volume-inuse-error
tofalse
- to save costs associated with watching all pods in the cluster. -
`-feature-gates**: A set of key/value pairs that describe alpha/experimental features of external-resizer.
AnnotateFsResize=true|false
(ALPHA - default=false): Store current size of pvc in pv's annotation, so as if pvc is deleted while expansion was pending on the node, the size of pvc can be restored to old value. This permits expansion on the node in case pvc was deleted while expansion was pending on the node (but completed in the controller). Use of this feature depends on Kubernetes version 1.21.
-
--kubeconfig <path>
: Path to Kubernetes client configuration that the external-resizer uses to connect to Kubernetes API server. When omitted, default token provided by Kubernetes will be used. This option is useful only when the external-resizer does not run as a Kubernetes pod, e.g. for debugging. Either this or--master
needs to be set if the external-resizer is being run out of cluster. -
--master <url>
: Master URL to build a client config from. When omitted, default token provided by Kubernetes will be used. This option is useful only when the external-resizer does not run as a Kubernetes pod, e.g. for debugging. Either this or--kubeconfig
needs to be set if the external-resizer is being run out of cluster. -
--metrics-address
: (deprecated) The TCP network address where the prometheus metrics endpoint will run (example::8080
which corresponds to port 8080 on local host). The default is empty string, which means metrics endpoint is disabled. -
--version
: Prints current external-resizer version and quits. -
All glog / klog arguments are supported, such as
-v <log level>
or-alsologtostderr
.
The external-resizer optionally exposes an HTTP endpoint at address:port specified by --http-endpoint
argument. When set, these two paths are exposed:
- Metrics path, as set by
--metrics-path
argument (default is/metrics
). - Leader election health check at
/healthz/leader-election
. It is recommended to run a liveness probe against this endpoint when leader election is used to kill external-resizer leader that fails to connect to the API server to renew its leadership. See kubernetes-csi/csi-lib-utils#66 for details.
Learn how to engage with the Kubernetes community on the community page.
You can reach the maintainers of this project at:
Participation in the Kubernetes community is governed by the Kubernetes Code of Conduct.