Kubernetes Deployment Yaml Example

To deploy  containerized applications in Kubernetes cluster  we use Kubernetes Deployment. We can create and manage a Deployment by using the Kubernetes Deployment Yaml file. We can define entire deployment object in a single yml file.  This object is responsible for creating the pods, and ensuring there are running.

Kubernetes Deployment Yaml Example

cat abcd.yml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mydep
  labels:
    dep: nginxdep
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.16.1
        ports:
        - containerPort: 80

Kubernetes deployment Yaml contains the following main specifications.

apiVersion

apiVersion specifies the API version of the Kubernetes deployment object.

kind

Kind describes the type of the object/resource to be created.

metadata

In metadata we can assign name and labels to deployment object.

spec

Spec represents which pods this deployment should take care. So the deployment will identify the pods using labels in selector. And we can mention number of pods should run always using replicas.

template

When the deployment creates pods, it will create them using this template.

Create the deployment using kubectl

using kubectl create command we can create deployment

syntax

kubectl create -f  <yml filename>

kubectl create -f abcd.yaml

List the Deployments

using kubectl get command we can list the deployments.

master $ kubectl get deployments

NAME    READY   UP-TO-DATE   AVAILABLE   AGE
mydep   3/3     3            3           12s

Get More Inforamtion about Deployment.

using kubectl describe command we can get more information about deployment.

Syntax:

kubectl describe deployments <deployment name>

master $ kubectl describe deployments mydep

Name:                   mydep
Namespace:              default
CreationTimestamp:      Sat, 07 Sep 2019 14:31:49 +0000
Labels:                 dep=nginxdep
Annotations:            deployment.kubernetes.io/revision: 1
                        kubectl.kubernetes.io/last-applied-configuration:
                          {"apiVersion":"apps/v1","kind":"Deployment","metadata":{"annotations":{},"labels":{"app":"nginx"},"name":"mydep","namespace":"default"},"s...
Selector:               app=nginx
Replicas:               3 desired | 3 updated | 3 total | 3 available | 0 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:  app=nginx
  Containers:
   nginx:
    Image:        nginx:1.16.1
    Port:         80/TCP
    Host Port:    0/TCP
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      True    MinimumReplicasAvailable
  Progressing    True    NewReplicaSetAvailable
OldReplicaSets:  <none>
NewReplicaSet:   mydep-59777878f8 (3/3 replicas created)
Events:
  Type    Reason             Age    From                   Message
  ----    ------             ----   ----                   -------
  Normal  ScalingReplicaSet  3m12s  deployment-controller  Scaled up replica set mydep-59777878f8 to 3

Here you can see whatever we defined in yml we can see that information. And also we can see number of pods created and available.

 

• Kubernetes Deployment Yaml example
• Kubernetes  Yaml Deployment example
• kubernetes deployment yaml reference