Dev-Ops why kubernetes(K8) and how to use(Basic Commands)?

What is K8?

Kubernetes, often abbreviated as K8s, is an open-source platform designed for automating the deployment, scaling, and management of containerized applications. It acts as a container orchestration system, handling the complexities of running and managing applications composed of multiple containers across a cluster of machines.

Here's a more detailed breakdown of why Kubernetes is used:

1. Automation and Orchestration:

Container Orchestration: Kubernetes automates the deployment, scaling, and management of containerized applications, simplifying complex deployments.
Automated Operations: It automates tasks like restarting failed containers, rescheduling workloads, and rolling out new versions of applications without downtime.

2. Scalability and Resource Efficiency:

Scalability: Kubernetes can automatically scale applications up or down based on demand, optimizing resource utilization and cost savings.
Resource Optimization: It efficiently allocates resources to containers, ensuring optimal performance and minimizing waste.

3. Reliability and Availability:

Self-Healing: Kubernetes automatically restarts failed containers and redistributes workloads, ensuring high availability of applications.
Rolling Updates: It enables seamless updates to applications with zero downtime, preventing disruptions to users.

4. Portability and Flexibility:

Cloud Portability: Kubernetes provides a consistent environment across different cloud providers and on-premises infrastructure, allowing for easy migration and deployment.
Flexibility: It supports various types of workloads, including stateless, stateful, and data-processing applications.

5. Developer Productivity and Efficiency:

Simplified Development: Kubernetes simplifies the process of building and deploying applications, allowing developers to focus on core application logic.
Infrastructure as Code: It enables developers to define infrastructure and configurations as code, promoting consistency and collaboration.

6. Open Source and Community Support:

Open Source: Kubernetes is an open-source project, fostering a large and active community that contributes to its continuous improvement and development.
Ecosystem: It has a rich ecosystem of tools and extensions that complement its core functionality, providing a comprehensive platform for container management.

In essence, Kubernetes is used to address the challenges of managing modern, containerized applications at scale. It offers automation, scalability, reliability, and portability, making it a powerful tool for both developers and operations teams.

Where it does fit in software development cycle.

In order to test kubernetes in your local machine, Following configuration/softwares are required.

Install both softwares in your machine and can test below commands.

To Start/stop/pause/unpause minikub cluster

minikube start/minikube stop/minikube pause/minikube unpause

Let's start the minikub K8 cluster

C:\Users\SandeepPachauri>minikube start
* minikube v1.36.0 on Microsoft Windows 11 Pro 10.0.26100.4652 Build 26100.4652
* Using the docker driver based on existing profile
* Starting "minikube" primary control-plane node in "minikube" cluster
* Pulling base image v0.0.47 ...
* Restarting existing docker container for "minikube" ...
! Failing to connect to https://registry.k8s.io/ from inside the minikube container
* To pull new external images, you may need to configure a proxy: https://minikube.sigs.k8s.io/docs/reference/networking/proxy/
* Preparing Kubernetes v1.33.1 on Docker 28.1.1 ...
* Verifying Kubernetes components...
  - Using image gcr.io/k8s-minikube/storage-provisioner:v5
* Enabled addons: default-storageclass, storage-provisioner
* Done! kubectl is now configured to use "minikube" cluster and "default" namespace by default

Check cluster pod details

	C:\Users\SandeepPachauri>kubectl get po -A
NAMESPACE        NAME                               READY   STATUS             RESTARTS      AGE
default          demo-deployment-7558778d8f-7skrm   1/1     Running            1 (93s ago)   130m
default          demo-deployment-7558778d8f-c74gb   1/1     Running            1 (93s ago)   94m
default          demo-deployment-7558778d8f-lkglw   1/1     Running            1 (93s ago)   61m
default          demo-deployment-7558778d8f-rqr7v   1/1     Running            1 (93s ago)   130m
kube-system      coredns-674b8bbfcf-2mcqd           0/1     Running            2 (88s ago)   140m
kube-system      etcd-minikube                      1/1     Running            2 (87s ago)   140m
kube-system      kube-apiserver-minikube            1/1     Running            2 (83s ago)   140m
kube-system      kube-controller-manager-minikube   1/1     Running            2 (93s ago)   140m
kube-system      kube-proxy-ntfmd                   1/1     Running            2 (93s ago)   140m
kube-system      kube-scheduler-minikube            1/1     Running            2 (93s ago)   140m
kube-system      storage-provisioner                1/1     Running            4 (93s ago)   140m
metallb-system   controller-dddd867f6-dl5gn         0/1     ErrImagePull       0             72m
metallb-system   speaker-6djt7                      0/1     ImagePullBackOff   0             72m

Check cluster information.

C:\Users\SandeepPachauri>kubectl cluster-info
Kubernetes control plane is running at https://127.0.0.1:52589
CoreDNS is running at https://127.0.0.1:52589/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.

List of kubernative resources.

C:\Users\SandeepPachauri>kubectl api-resources
NAME                                SHORTNAMES   APIVERSION                        NAMESPACED   KIND
bindings                                         v1                                true         Binding
componentstatuses                   cs           v1                                false        ComponentStatus
configmaps                          cm           v1                                true         ConfigMap
endpoints                           ep           v1                                true         Endpoints

Create resources in kubernative

kubectl create -f <filename.yaml>

Create resources in kubernative using inline command

C:\Users\SandeepPachauri>kubectl create deployment demo-deployment --image=nginx:latest --replicas=2
deployment.apps/demo-deployment created

Get running pods in cluster

C:\Users\SandeepPachauri>kubectl get pods
NAME                               READY   STATUS    RESTARTS        AGE
demo-deployment-7558778d8f-7skrm   1/1     Running   1 (4m23s ago)   133m
demo-deployment-7558778d8f-c74gb   1/1     Running   1 (4m23s ago)   96m
demo-deployment-7558778d8f-lkglw   1/1     Running   1 (4m23s ago)   64m
demo-deployment-7558778d8f-rqr7v   1/1     Running   1 (4m23s ago)   133m

Create dedicated namespace(Domain).

C:\Users\SandeepPachauri>kubectl create namespace app-dev
namespace/app-dev created

C:\Users\SandeepPachauri>kubectl create namespace app-prod
namespace/app-prod created

Get all namespace(domain)

C:\Users\SandeepPachauri>kubectl get namespace
NAME              STATUS   AGE
app-dev           Active   130m
app-prod          Active   129m
default           Active   144m
kube-node-lease   Active   144m
kube-public       Active   144m
kube-system       Active   144m
metallb-system    Active   77m

Get specific pod complete information

C:\Users\SandeepPachauri>kubectl describe pod demo-deployment-7558778d8f-7skrm
Name:             demo-deployment-7558778d8f-7skrm
Namespace:        default
Priority:         0
Service Account:  default
Node:             minikube/192.168.49.2
Start Time:       Wed, 13 Aug 2025 14:39:28 +0530
Labels:           app=demo-deployment
                  pod-template-hash=7558778d8f
Annotations:      <none>
Status:           Running
IP:               10.244.0.11
IPs:
  IP:           10.244.0.11
Controlled By:  ReplicaSet/demo-deployment-7558778d8f

Get logs from pod

C:\Users\SandeepPachauri>kubectl logs -f demo-deployment-7558778d8f-7skrm
/docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
/docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
/docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
10-listen-on-ipv6-by-default.sh: info: Getting the checksum of /etc/nginx/conf.d/default.conf
10-listen-on-ipv6-by-default.sh: info: Enabled listen on IPv6 in /etc/nginx/conf.d/default.conf
/docker-entrypoint.sh: Sourcing /docker-entrypoint.d/15-local-resolvers.envsh
/docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
/docker-entrypoint.sh: Launching /docker-entrypoint.d/30-tune-worker-processes.sh
/docker-entrypoint.sh: Configuration complete; ready for start up
2025/08/13 11:20:04 [notice] 1#1: using the "epoll" event method
2025/08/13 11:20:04 [notice] 1#1: nginx/1.29.0
2025/08/13 11:20:04 [notice] 1#1: built by gcc 12.2.0 (Debian 12.2.0-14+deb12u1)
2025/08/13 11:20:04 [notice] 1#1: OS: Linux 6.6.87.2-microsoft-standard-WSL2
2025/08/13 11:20:04 [notice] 1#1: getrlimit(RLIMIT_NOFILE): 1048576:1048576
2025/08/13 11:20:04 [notice] 1#1: start worker processes
2025/08/13 11:20:04 [notice] 1#1: start worker process 29
2025/08/13 11:20:04 [notice] 1#1: start worker process 30
2025/08/13 11:20:04 [notice] 1#1: start worker process 31
2025/08/13 11:20:04 [notice] 1#1: start worker process 32
2025/08/13 11:20:04 [notice] 1#1: start worker process 33
2025/08/13 11:20:04 [notice] 1#1: start worker process 34
2025/08/13 11:20:04 [notice] 1#1: start worker process 35
2025/08/13 11:20:04 [notice] 1#1: start worker process 36

Get resources from pod.

C:\Users\SandeepPachauri>kubectl exec demo-deployment-7558778d8f-7skrm -- ls /
bin
boot
dev
docker-entrypoint.d
docker-entrypoint.sh
etc
home
lib
lib64
media
mnt
opt
proc
root
run
sbin
srv
sys
tmp
usr
var

In case any specific folder resources to be checked.

C:\Users\SandeepPachauri>kubectl exec demo-deployment-7558778d8f-7skrm -- ls /bin
[
addpart
apt
apt-cache
apt-cdrom
apt-config
apt-get
apt-key

Get shell/script access in a pod


C:\Users\SandeepPachauri>kubectl exec -it demo-deployment-7558778d8f-7skrm -- /bin/bash

root@demo-deployment-7558778d8f-7skrm:/# ls
bin  boot  dev  docker-entrypoint.d  docker-entrypoint.sh  etc  home  lib  lib64  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var

Get list of deployments.

C:\Users\SandeepPachauri>kubectl get deployments
NAME              READY   UP-TO-DATE   AVAILABLE   AGE
demo-deployment   4/4     4            4           138m

Get details of specific deployment in YAML format.

C:\Users\SandeepPachauri>kubectl get deployment demo-deployment -o yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  annotations:
    deployment.kubernetes.io/revision: "1"
  creationTimestamp: "2025-08-13T09:09:28Z"
  generation: 5
  labels:
    app: demo-deployment
  name: demo-deployment
  namespace: default
  resourceVersion: "7757"
  uid: d8310c7c-69d7-4789-bfc6-0ff67691c8c0
spec:
  progressDeadlineSeconds: 600
  replicas: 4
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      app: demo-deployment
  strategy:
    rollingUpdate:

Scale(Increase/decrease) no of instance for running pod

C:\Users\SandeepPachauri>kubectl scale deployment demo-deployment --replicas=5
deployment.apps/demo-deployment scaled

C:\Users\SandeepPachauri>kubectl get deployments
NAME              READY   UP-TO-DATE   AVAILABLE   AGE
demo-deployment   5/5     5            5           141m

Check the deployment status of any pod/image

C:\Users\SandeepPachauri>kubectl rollout status deployment demo-deployment
deployment "demo-deployment" successfully rolled out

Get list of services running in cluster

C:\Users\SandeepPachauri>kubectl get service
NAME              TYPE           CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
demo-service      ClusterIP      10.111.65.33    <none>        80/TCP         99m
demo-service-lb   LoadBalancer   10.107.127.0    <pending>     80:30101/TCP   82m
demo-service-np   NodePort       10.96.138.119   <none>        80:31452/TCP   92m
kubernetes        ClusterIP      10.96.0.1       <none>        443/TCP        151m

Expose a deployment as service.

C:\Users\SandeepPachauri>kubectl expose deployment/demo-deployment --name=demo-service --port=80
service/demo-service exposed

C:\Users\SandeepPachauri>kubectl get service
NAME           TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)   AGE
demo-service   ClusterIP   10.111.65.33   <none>        80/TCP    4s
kubernetes     ClusterIP   10.96.0.1      <none>        443/TCP   51m

Running a service: Note services can be only accessed from one of the pod where its running. To do so, you have login into pod as shell/bash.

kubectl exec -it demo-deployment-7558778d8f-7skrm -- /bin/bash

root@demo-deployment-7558778d8f-7skrm:/# curl 10.111.65.33:80

Expose API service to node port service so it can be accessed outside of cluster(on the browser).

C:\Users\SandeepPachauri>kubectl expose deployment/demo-deployment --name=demo-service-np --port=80 --target-port=80 --type=NodePort

service/demo-service-np exposed

Get external/internal ip of cluster to run.

C:\Users\SandeepPachauri>kubectl get nodes -o wide
NAME       STATUS   ROLES           AGE    VERSION   INTERNAL-IP    EXTERNAL-IP   OS-IMAGE             KERNEL-VERSION                     CONTAINER-RUNTIME
minikube   Ready    control-plane   153m   v1.33.1   192.168.49.2   <none>        Ubuntu 22.04.5 LTS   6.6.87.2-microsoft-standard-WSL2   docker://28.1.1

Here we can see external IP is null so lets setup a IP.

kubectl apply -f https://raw.githubusercontent.com/google/metallb/v0.8.3/manifests/metallb.yaml

Access service on browser with internal/external ip.

http://192.168.49.2:31452/

Expose API service to load balance port service so it can be accessised outside of cluster(on the browser).

C:\Users\SandeepPachauri>kubectl expose deployment/demo-deployment --name=demo-service-lb --port=80 --target-port=80 --type=LoadBalancer

service/demo-service-lb exposed

Edit pod in notepad/text editor.

C:\Users\SandeepPachauri>kubectl edit pod demo-deployment-7558778d8f-7skrm

Download pod configuration in local machine as yaml.

C:\Users\SandeepPachauri>kubectl get pod demo-deployment-7558778d8f-7skrm -o yaml > prod.yaml

Edit deployment:

C:\Users\SandeepPachauri>kubectl edit deployment demo-deployment

Cluster details.

C:\Users\SandeepPachauri>kubectl config view
apiVersion: v1
clusters:
- cluster:
    certificate-authority: C:\Users\SandeepPachauri\.minikube\ca.crt
    extensions:
    - extension:
        last-update: Wed, 13 Aug 2025 16:49:47 IST
        provider: minikube.sigs.k8s.io
        version: v1.36.0
      name: cluster_info
    server: https://127.0.0.1:52589
  name: minikube
contexts:
- context:
    cluster: minikube
    extensions:
    - extension:
        last-update: Wed, 13 Aug 2025 16:49:47 IST
        provider: minikube.sigs.k8s.io
        version: v1.36.0
      name: context_info
    namespace: default
    user: minikube
  name: minikube
current-context: minikube
kind: Config
preferences: {}
users:
- name: minikube
  user:
    client-certificate: C:\Users\SandeepPachauri\.minikube\profiles\minikube\client.crt
    client-key: C:\Users\SandeepPachauri\.minikube\profiles\minikube\client.key

Get clusters details connected.

C:\Users\SandeepPachauri>kubectl config get-contexts
CURRENT   NAME       CLUSTER    AUTHINFO   NAMESPACE
*         minikube   minikube   minikube   default

Get all services/deployment running in cluster

C:\Users\SandeepPachauri>kubectl get all
NAME                                   READY   STATUS    RESTARTS      AGE
pod/demo-deployment-7558778d8f-7skrm   1/1     Running   1 (18m ago)   147m
pod/demo-deployment-7558778d8f-c74gb   1/1     Running   1 (18m ago)   110m
pod/demo-deployment-7558778d8f-hpmc7   1/1     Running   0             6m40s
pod/demo-deployment-7558778d8f-lkglw   1/1     Running   1 (18m ago)   78m
pod/demo-deployment-7558778d8f-rqr7v   1/1     Running   1 (18m ago)   147m

NAME                      TYPE           CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
service/demo-service      ClusterIP      10.111.65.33    <none>        80/TCP         105m
service/demo-service-lb   LoadBalancer   10.107.127.0    <pending>     80:30101/TCP   87m
service/demo-service-np   NodePort       10.96.138.119   <none>        80:31452/TCP   98m
service/kubernetes        ClusterIP      10.96.0.1       <none>        443/TCP        156m

NAME                              READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/demo-deployment   5/5     5            5           147m

NAME                                         DESIRED   CURRENT   READY   AGE
replicaset.apps/demo-deployment-7558778d8f   5         5         5       147m

Dev-Ops why kubernetes(K8) and how to use(Basic Commands)? - Part 6

Sandeep Pachauri

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Here's a more detailed breakdown of why Kubernetes is used:

Where it does fit in software development cycle.

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What is K8?

Here's a more detailed breakdown of why Kubernetes is used:

Where it does fit in software development cycle.

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