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Learn Kubernetes: A Deep Dive

How to Create a Deployment

Explore how to create Kubernetes Deployments using a declarative approach with a deploy.yml file. Understand key components such as replicas, selectors, rollout strategies, and revision history to manage scalable, self-healing Pods efficiently.

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Declaratively create a Deployment

To create a Deployment, we’ll use the deploy.yml file shown in the following snippet. It defines a single-container Pod wrapped in a Deployment. It’s annotated and snipped to draw attention to the parts we’ll focus on.

YAML
kind: Deployment
apiVersion: apps/v1
metadata:
  name: hello-deploy       <<==== Deployment name (must be valid DNS name)
spec:
  replicas: 10             <<==== Number of Pod replicas to deploy & manage
  selector:                
    matchLabels:
      app: hello-world
  revisionHistoryLimit: 5
  progressDeadlineSeconds: 300    
  minReadySeconds: 10
  strategy:                <<==== This block defines rolling update settings
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 1
      maxSurge: 1
  template:                <<==== Below here is the Pod template
    metadata:
      labels:
        app: hello-world
    spec:
      containers:
      - name: hello-pod
        image: nigelpoulton/k8sbook:1.0
        ports:
        - containerPort: 8080

There’s a lot going on in the file, so let’s explain the most important bits.

The first two lines, i.e., line 1 and line 2, tell Kubernetes to create a Deployment object based on the version of the Deployment resource defined in the apps/v1 API.

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