How do i deploy a kubernetes app using a yaml file?

amurleopard

This example is fairly common on the internet, it deploys a nginx webserver, labels it, creates 3 replicasets, specifies the app should run on port 80. Looking at it, you can break down blocks of it. There are two spec: sections because one is for the Deployment, and one is for the container template.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: webserver
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:alpine
        ports:
        - containerPort: 80

To deploy from this file do the following:

$ kubectl create -f webserver.yaml 
deployment "webserver" created

$ kubectl get replicasets
NAME                   DESIRED   CURRENT   READY     AGE
webserver-77d8994b6f   3         3         3         41s

$ kubectl get pods -l app==nginx
NAME                         READY     STATUS    RESTARTS   AGE
webserver-77d8994b6f-fn9p9   1/1       Running   0          1m
webserver-77d8994b6f-pr28r   1/1       Running   0          1m
webserver-77d8994b6f-qnqlq   1/1       Running   0          1m