This blog is a continuation of previous blog series https://goglides.io/2020/03/03/limit-range-kubernetes/
Limiting Storage resources
Using LimitRange it is possible to enforce minimum and maximum size of storage resources that can be requested by each PersistentVolumeClaim in a namespace.
Create a file limitrange-storage.yaml
apiVersion: v1
kind: Namespace
metadata:
name: limitrange-storage-demo3
---
apiVersion: v1
kind: LimitRange
metadata:
name: storagelimits
namespace: limitrange-storage-demo3
spec:
limits:
- type: PersistentVolumeClaim
max:
storage: 2Gi
min:
storage: 1Gi
Apply the YAML file using:
kubectl apply -f limitrange-storage.yaml
Describe the created object:
kubectl describe -f limitrange-storage.yaml
Output:
Name: limitrange-storage-demo3
Labels: <none>
Annotations: kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"v1","kind":"Namespace","metadata":{"annotations":{},"name":"limitrange-storage-demo3"}}
Status: Active
No resource quota.
Resource Limits
Type Resource Min Max Default Request Default Limit Max Limit/Request Ratio
---- -------- --- --- --------------- ------------- -----------------------
PersistentVolumeClaim storage 1Gi 2Gi - - -
Name: storagelimits
Namespace: limitrange-storage-demo3
Type Resource Min Max Default Request Default Limit Max Limit/Request Ratio
---- -------- --- --- --------------- ------------- -----------------------
PersistentVolumeClaim storage 1Gi 2Gi - - -
Now let’s test the constraint working or not, first test lower limits (pvc-limit-lower.yaml)
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: pvc-limit-lower
namespace: limitrange-storage-demo3
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 500Mi
apply YAML,
kubectl apply -f pvc-limit-lower.yaml
Output:
Error from server (Forbidden): error when creating "limitrange-storage.yaml": persistentvolumeclaims "pvc-limit-lower" is forbidden: minimum storage usage per PersistentVolumeClaim is 1Gi, but request is 500Mi
Since limitRange rule saying min storage should be 1Gi, so this PersistentVolumeClaim not satisfying this constraint and hence failed.
Now try with higher limits (pvc-limit-higher.yaml)
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: pvc-limit-greater
namespace: limitrange-storage-demo3
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 5Gi
apply YAML,
kubectl apply -f pvc-limit-higher.yaml
Output:
Error from server (Forbidden): error when creating "limitrange-storage.yaml": persistentvolumeclaims "pvc-limit-greater" is forbidden: maximum storage usage per PersistentVolumeClaim is 2Gi, but request is 5Gi
This one is also not satisfying the constraint and failed gracefully.
Now test with PersistentVolumeClaim which satisfy the constraint (pvc-limit-matching-constraint.yaml)
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: pvc-limit-matching-constraint
namespace: limitrange-storage-demo3
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1.5Gi
apply YAML,
kubectl apply -f pvc-limit-matching-constraint.yaml
Output:
persistentvolumeclaim/pvc-limit-matching-constraint created
Describe object,
kubectl describe -f pvc-limit-matching-constraint.yaml
Output:
Name: pvc-limit-matching-constraint
Namespace: limitrange-storage-demo3
StorageClass: hostpath
Status: Bound
Volume: pvc-8f2271bc-d716-4ff5-9d3c-9889bf7d677b
Labels: <none>
Annotations: control-plane.alpha.kubernetes.io/leader:
{"holderIdentity":"3789e204-58b4-11ea-b9a6-985aeb8efcc4","leaseDurationSeconds":15,"acquireTime":"2020-02-26T18:20:07Z","renewTime":"2020-...
kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"v1","kind":"PersistentVolumeClaim","metadata":{"annotations":{},"name":"pvc-limit-matching-constraint","namespace":"limitra...
pv.kubernetes.io/bind-completed: yes
pv.kubernetes.io/bound-by-controller: yes
volume.beta.kubernetes.io/storage-provisioner: docker.io/hostpath
Finalizers: [kubernetes.io/pvc-protection]
Capacity: 1536Mi
Access Modes: RWO
VolumeMode: Filesystem
Mounted By: <none>
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal ExternalProvisioning 98s (x2 over 98s) persistentvolume-controller waiting for a volume to be created, either by external provisioner "docker.io/hostpath" or manually created by system administrator
Normal Provisioning 98s docker.io/hostpath ggg.local 3789e204-58b4-11ea-b9a6-985aeb8efcc4 External provisioner is provisioning volume for claim "limitrange-storage-demo3/pvc-limit-matching-constraint"
Normal ProvisioningSucceeded 98s docker.io/hostpath ggg.local 3789e204-58b4-11ea-b9a6-985aeb8efcc4 Successfully provisioned volume pvc-8f2271bc-d716-4ff5-9d3c-9889bf7d677b
You can see PersistentVolume is created,
kubectl get pv
Output:
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pvc-8f2271bc-d716-4ff5-9d3c-9889bf7d677b 1536Mi RWO Delete Bound limitrange-st
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