4. YAML Configuration File

Introduction

• Config File is written in YAML Format

• Config File should be stored with the code inside SCM

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3 Parts of K8 Config File

1. Metadata

2. Specification

3. Status (Auto Generated & Added by K8)

   • K8 Gets Status from etcd

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Template

• The specified kind has its own metadata and spec

• Pod has also a section of its own which contains its own configuration

Labels & Connectors

• Metadata section contain the labels

• Spec section contains the selectors

Connecting Deployment to Pods

• Deployment looks which pods belong to it using labels (key value pairs)

• The label is matched by the selector

Connecting Services to Deployments

• Similar concept as connecting deployment to pods

Ports in Service & Pods

• Service listens on port and forwards the request to target port which must be of a pod

Minimal Deployment File

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.16
        ports:
        - containerPort: 8080

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Minimal Service File

apiVersion: v1
kind: Service
metadata:
  name: nginx-service
spec:
  selector:
    app: nginx
  ports:
    - protocol: TCP
      port: 80
      targetPort: 8080

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