Kubernetes : Deploy only in one node-pool - kubernetes

Question

I'm currently creating a Kubernetes cluster for a production environment.
In my cluster, I have 2 node-pool, let's call them api-pool and web-pool
In my api-pool, I have 2 nodes with 4CPU and 15Gb of RAM each.
I'm trying to deploy 8 replicas of my api in my api-pool, each replicas should have 1CPU and 3.5Gi of RAM.
My api.deployment.yaml looks something like this :
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: api-dev
spec:
replicas: 8
selector:
matchLabels:
app: my-api
template:
metadata:
labels:
app: my-api
spec:
containers:
- name: api-docker
image: //MY_IMAGE
imagePullPolicy: Always
envFrom:
- configMapRef:
name: api-dev-env
- secretRef:
name: api-dev-secret
ports:
- containerPort: 80
resources:
requests:
cpu: "1"
memory: "3.5Gi"
But my problem is that Kubernetes is deploying the pods on nodes on my web-pool as well as in my api-pool but I want those pods to be deployed only in my api-pool.
I tried to label my nodes of the api-pool to use a selector that matches labels but it doesn't work and I'm not sure it's supposed to work that way.
How can I precise to K8s to deploy those 8 replicas only in my api-pool ?

Answer 1

You can use a nodeselector which is the simplest recommended form of node selection constraint.
label the nodes of api-pool with pool=api
kubectl label nodes nodename pool=api
Add nodeSelector in pod spec.
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: api-dev
spec:
replicas: 8
selector:
matchLabels:
app: my-api
template:
metadata:
labels:
app: my-api
spec:
containers:
- name: api-docker
image: //MY_IMAGE
imagePullPolicy: Always
envFrom:
- configMapRef:
name: api-dev-env
- secretRef:
name: api-dev-secret
ports:
- containerPort: 80
resources:
requests:
cpu: "1"
memory: "3.5Gi"
nodeSelector:
pool: api
For mode advanced use cases you can use node affinity.