set priorityclass by default for a namespace - kubernetes

Question

I would like to know how it's possible to set a priorityClass by default for all pods in a specific namespace without using a
globalvalue: true
may be with admission controller but i don't know.
Do you have an concret example for that ?

Answer 1

PriorityClass : A PriorityClass is a non-namespaced object
PriorityClass also has two optional fields: globalDefault and description.
The globalDefault field indicates that the value of this PriorityClass should be used for Pods without a priorityClassName.
Only one PriorityClass with globalDefault set to true can exist in the system. If there is no PriorityClass with globalDefault set, the priority of Pods with no priorityClassName is zero.
Create Priority Class as using below yaml (no globalDefault flag is set)
apiVersion: scheduling.k8s.io/v1
kind: PriorityClass
metadata:
name: high-priority
value: 1000000
description: "This priority class should be used for pods."
$ kubectl get priorityclasses.scheduling.k8s.io
NAME VALUE GLOBAL-DEFAULT AGE
high-priority 1000000 false 10s
Now add priority class to pod manifest and schedule them in your namespace
$ kubectl create namespace priority-test
namespace/priority-test created
$ kubectl get namespaces
NAME STATUS AGE
default Active 43m
kube-node-lease Active 43m
kube-public Active 43m
kube-system Active 43m
priority-test Active 5s
Example : pod.yaml
apiVersion: v1
kind: Pod
metadata:
name: nginx
spec:
containers:
- name: nginx
image: nginx
priorityClassName: high-priority
$ kubectl apply -f pod.yaml -n priority-test
pod/nginx created
ubuntu#k8s-master-1:~$ kubectl get all -n priority-test
NAME READY STATUS RESTARTS AGE
pod/nginx 1/1 Running 0 25s
$ kubectl describe pod -n priority-test nginx | grep -i priority
Namespace: priority-test
Priority: 1000000
Priority Class Name: high-priority
Normal Scheduled <unknown> default-scheduler Successfully assigned priority-test/nginx to worker-1

Answer 2

Currently per namespace priorities are not possible.
But you can achieve similar result if instead you set default priorityClass with globalDefault: true and e.g. value: 1000. Next create another lower priority class and with e.g. value: 100 and add it to all dev/staging pods.
Btw. not directly related to the question but it would be much easier to accomplish what you need if you use nodeSelectors and schedule dev pods to separate nodes. This way production pods don't have to compete for resources with non-essential pods.