Limit Storage Consumption

    The following resources are used in the demonstration: ResourceQuota, , and PersistentVolumeClaim.

    The admin would like to limit:

    1. The number of persistent volume claims in a namespace
    2. The amount of storage each claim can request
    3. The amount of cumulative storage the namespace can have

    Adding a LimitRange to a namespace enforces storage request sizes to a minimum and maximum. Storage is requested via PersistentVolumeClaim. The admission controller that enforces limit ranges will reject any PVC that is above or below the values set by the admin.

    In this example, a PVC requesting 10Gi of storage would be rejected because it exceeds the 2Gi max.

    Admins can limit the number of PVCs in a namespace as well as the cumulative capacity of those PVCs. New PVCs that exceed either maximum value will be rejected.

    In this example, a 6th PVC in the namespace would be rejected because it exceeds the maximum count of 5. Alternatively, a 5Gi maximum quota when combined with the 2Gi max limit above, cannot have 3 PVCs where each has 2Gi. That would be 6Gi requested for a namespace capped at 5Gi.

    1. kind: ResourceQuota
    2. metadata:
    4. spec:
    5.   hard:
    6.     requests.storage: "5Gi"

    A limit range can put a ceiling on how much storage is requested while a resource quota can effectively cap the storage consumed by a namespace through claim counts and cumulative storage capacity. The allows a cluster-admin to plan their cluster’s storage budget without risk of any one project going over their allotment.