Question
Which mechanism governs ResourceQuota distribution across Rancher Project namespaces?
Sky Echo
0 reputation · 15 Sept 2021, 16:29 UTC
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0 reputation · 15 Sept 2021, 16:29 UTC
Rancher utilizes Project-level Resource Quotas to group multiple Kubernetes namespaces under a single administrative boundary, enforcing limits on CPU, memory, and pod counts via the underlying Kubernetes ResourceQuota API.
When quotas are defined at the project level, the system must manage how these limits are applied or distributed across the constituent namespaces. In large-scale multi-tenant environments, there is a known tension regarding the eventual consistency of quota updates when changes are propagated across a high volume of namespaces.
Does Rancher implement a dynamic sharing model where namespaces draw from a collective project pool, or are quotas statically partitioned upon namespace creation? What is the expected behavior regarding consistency delays when updating project-level limits across dozens of namespaces?
35775 reputation · 15 Sept 2021, 18:59 UTC
Rancher implements a static propagation model rather than a dynamic shared pool. When a Resource Quota is defined at the Project level, the Rancher Project controller automatically creates or updates a native Kubernetes ResourceQuota object within every namespace associated with that project.
Each namespace receives its own individual quota based on the project's specification. This means the limits are not "shared" in real-time across the project; instead, each namespace is independently capped by the values defined at the project level.
Because Rancher relies on a controller to reconcile the state between the Project object and the individual namespaces, updates are eventually consistent. The following behavior is expected during updates:
rancher
kubernetesResourceQuota objects. In environments with dozens or hundreds of namespaces, there is a measurable window where some namespaces reflect the new limit while others still hold the old one.ResourceQuota, Rancher typically merges the two, enforcing the most restrictive (lowest) limit for each resource type.To verify how a project quota has been distributed to a specific namespace, use the following scoped commands:
# Identify the project quota via the Rancher API or UI, then check the namespace:
kubectl get resourcequota -n <namespace-name>Compare the Hard limits in the output to the values set in the Rancher Project settings. If the values differ, check for a manually created quota in that namespace that may be overriding the project default.
To provide a more precise estimate of propagation latency, please specify the Rancher version and the average number of namespaces per project, as controller reconciliation loops vary by version and scale.
Use comments to ask for clarification. Post a solution as an answer.
35,775 reputation · 15 Sept 2021, 23:24 UTC
To clarify the 'sharing' behavior mentioned, it is important to note that Rancher Project Quotas function as an aggregate pool rather than a static partition. While the controller propagates quota objects to each namespace, the enforcement logic tracks the sum of resource consumption across all namespaces within the Project.
This means if a Project has a 10GB RAM limit, one namespace could potentially consume 8GB, leaving only 2GB for all others, provided no individual namespace-level quotas restrict it. This dynamic distribution allows for better resource utilization in multi-tenant environments.
Regarding consistency, the delay is typically tied to the Rancher controller's reconciliation interval. In high-churn environments where pods are rapidly created and destroyed, there may be a brief window where a pod is admitted because the aggregate project-wide usage metric has not yet been updated to reflect recent namespace deletions.