apiVersion: apps/v1
# Determines YAML versioned schema.
kind: Deployment
# Describes the resource defined in this file.
metadata:
  name: nginx-one
  labels:
    system: secondary
# Required string which defines object within namespace.
  namespace: accounting
# Existing namespace resource will be deployed into.
spec:
  selector:
    matchLabels:
      system: secondary
# Declaration of the label for the deployment to manage
  replicas: 2
# How many Pods of following containers to deploy
  template:
    metadata:
      labels:
        system: secondary
# Some string meaningful to users, not cluster. Keys
# must be unique for each object. Allows for mapping
# to customer needs.
    spec:
      containers:
# Array of objects describing containerized application with a Pod.
# Referenced with shorthand spec.template.spec.containers
      - image: nginx:1.20.1
# The Docker image to deploy
        imagePullPolicy: Always
        name: nginx
# Unique name for each container, use local or Docker repo image
        ports:
        - containerPort: 8080
          protocol: TCP
# Optional resources this container may need to function.
      nodeSelector:
        system: secondOne
# One method of node affinity.