Available as of v2.1.0
In situations where several teams share a cluster, one team may overconsume the resources available: CPU, memory, storage, services, Kubernetes objects like pods or secrets, and so on. To prevent this overconsumption, you can apply a resource quota, which is a Rancher feature that limits the resources available to a project or namespace.
Resource Quotas in Rancher
In a standard Kubernetes deployment, resource quotas are applied to individual namespaces. However, you cannot apply the quota to your namespaces simultaneously with a single action. Instead, the resource quota must be applied multiple times.
In the following diagram, a Kubernetes admin is trying to enforce a resource quota without Rancher. The admin wants to apply a resource quota that sets the same CPU and memory limit to every namespace in his cluster (
Namespace 1-4) . However, in the base version of Kubernetes, each namespace requires a unique resource quota. The admin has to create four different resource quotas that have the same specs configured (
Resource Quota 1-4) and apply them individually.
Base Kubernetes: Unique Resource Quotas Being Applied to Each Namespace
Resource quotas are a little different in Rancher. In Rancher, you apply a resource quota to the project, and then the quota propagates to each namespace, whereafter Kubernetes enforces you limits using the native version of resource quotas. If you want to change the quota for a specific namespace, you can override it.
This set of values configures an overall resource limit for the project. If you try to add a new namespace to the project, Rancher uses the limits you’ve set to validate that the project has enough resources to accommodate the namespace. In other words, if you try to add a namespace to a project near its resource quota, Rancher blocks you from adding the namespace.
Namespace Default Limits:
This value is the default resource limit available for each namespace. The project propagates the limit to each namespace. Each namespace is bound to this default limit unless you override it.
In the following diagram, a Rancher admin wants to apply a resource quota that sets the same CPU and memory limit for every namespace in their project (
Namespace 1-4). However, in Rancher, the admin can set a resource quota for the project (
Project Resource Quota) rather than individual namespaces. This quota includes resource limits for both the entire project (
Project Limit) and individual namespaces (
Namespace Default Limit). Rancher then propagates this quota to each namespace (
Namespace Resource Quota).
Rancher: Resource Quotas Propagating to Each Namespace
The following table explains the key differences between the two quota types.
|Rancher Resource Quotas||Kubernetes Resource Quotas|
|Applies to projects and namespace.||Applies to namespaces only.|
|Creates resource pool for all namespaces in project.||Applies static resource limits to individual namespaces.|
|Applies resource quotas to namespaces through propagation.||Applies only to the assigned namespace.|
Creating Resource Quotas
You can create resource quotas in the following contexts:
Resource Quota Types
When you create a resource quota, you are configuring the pool of resources available to the project. You can set the following resource limits for the following resource types.
|CPU Limit||The maximum amount of CPU (in millicores) allocated to the project/namespace.1|
|CPU Reservation||The minimum amount of CPU (in millicores) guaranteed to the project/namespace.1|
|Memory Limit||The maximum amount of memory (in bytes) allocated to the project/namespace.1|
|Memory Reservation||The minimum amount of memory (in bytes) guaranteed to the project/namespace.1|
|Storage Reservation||The minimum amount of storage (in gigabytes) guaranteed to the project/namespace.|
|Services Load Balancers||The maximum number of load balancers services that can exist in the project/namespace.|
|Services Node Ports||The maximum number of node port services that can exist in the project/namespace.|
|Pods||The maximum number of pods that can exist in the project/namespace in a non-terminal state (i.e., pods with a state of
|Services||The maximum number of services that can exist in the project/namespace.|
|ConfigMaps||The maximum number of ConfigMaps that can exist in the project/namespace.|
|Persistent Volume Claims||The maximum number of persistent volume claims that can exist in the project/namespace.|
|Replications Controllers||The maximum number of replication controllers that can exist in the project/namespace.|
|Secrets||The maximum number of secrets that can exist in the project/namespace.|
1 In the quota, if you set CPU or Memory limits, all containers you create in the project / namespace must explicitly satisfy the quota. See the Kubernetes documentation for more details.
Overriding the Default Limit for a Namespace
Although the Namespace Default Limit propagates from the project to each namespace, in some cases, you may need to increase (or decrease) the performance for a specific namespace. In this situation, you can override the default limits by editing the namespace.
In the diagram below, the Rancher admin has a resource quota in effect for their project. However, the admin wants to override the namespace limits for
Namespace 3 so that it performs better. Therefore, the admin raises the namespace limits for
Namespace 3 so that the namespace can access more resources.
Namespace Default Limit Override