What is manifest file?

• A definition file (.yaml or .josn) that is used to create kubernetes resource by posting to API server
• Kubernetes manifests (.yaml or .json) are used to create, modify and delete Kubernetes resources such as pods, deployments, services or ingresses
• It is very common to define manifests in form of .yaml files and send them to the Kubernetes API Server via commands such as:
  • kubectl apply -f my-file.yaml
  • kubectl delete -f my-file.yaml
• Manifest files define desired state of the cluster and the controllers ensure that the desired state is achieved

Structure Of manifest file

Required Fields

• apiVersion : Which version of the Kubernetes API you’re using to create this object
• kind : What kind of object you want to create
• metadata : Data that helps uniquely identify the object, including a name string, UID, and optional namespace
• spec : What state you desire for the object

Example: deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 2 # tells deployment to run 2 pods matching the template
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80

Kinds Of K8s objects

• Command to list resources: kubectl api-resources -o wide
• https://stackoverflow.com/questions/53053888/where-is-the-complete-list-of-kubernetes-objects
• Some of the Kubernetes Objects:
  • Pods
  • Namespaces
  • ReplicaSets
  • StatefulSets
  • Services
  • ConfigMaps
  • Secrets
  • Volumes

Links

• Configuration Best Practices: https://kubernetes.io/docs/concepts/configuration/overview/
• https://github.com/kubernetes/examples