Kubernetes for Serverless Applications

Deployments

One thing you may be thinking you will be able to do with a ReplicaSet is rolling upgrades and rollbacks. Unfortunately, ReplicaSets can only replicate the same version of a pod; luckily, this is where deployments come in.

A deployment controller is designed to update a ReplicaSet or pod. Lets use NGINX as an example. As you can see from the following definition, we have 3 replicas all running NGINX version 1.9.14:

apiVersion: apps/v1beta1kind: Deploymentmetadata:  name: nginx-deploymentspec:  replicas: 3  template:    metadata:      labels:        app: nginx    spec:      containers:      - name: nginx        image: nginx:1.9.14        ports:        - containerPort: 80

kubectl is the command-line client for Kubernetes; we will be looking at this in more detail in our next chapter. ...