What is a Resource Quota in Kubernetes

Question

Can anybody explain what is resource quota and why do we need them?

Answer 1

A resource quota, defined by a ResourceQuota object, provides constraints that limit aggregate resource consumption per namespace. 

It can limit the quantity of objects that can be created in a namespace by type, as well as the total amount of compute resources that may be consumed by resources in that project.

Resource quotas work like this:

• Different teams work in different namespaces. Currently this is voluntary, but support for making this mandatory via ACLs is planned.

• The administrator creates one or more ResourceQuotas for each namespace.

• Users create resources (pods, services, etc.) in the namespace, and the quota system tracks usage to ensure it does not exceed hard resource limits defined in a ResourceQuota.

• If creating or updating a resource violates a quota constraint, the request will fail with HTTP status code 403 FORBIDDEN with a message explaining the constraint that would have been violated.

• If quota is enabled in a namespace for compute resources like cpu and memory, users must specify requests or limits for those values; otherwise, the quota system may reject pod creation. 
  
  Hint: Use the LimitRanger admission controller to force defaults for pods that make no compute resource requirements.