kubernetes 101 for developers

This is a hands-on tutorial to deploy basic services with kubectl and helm on kubernetes cluster running on local machine.

👉🏼 No cloud account needed.

👉🏼 No Docker desktop needed.

This tutorial is composed on Intel based Macbook, all the commands and processes should be same for any other machine except tool installation commands.

Table of contents

---

• System Setup
• kubectl
  • Get ready
  • Create a Deployment
  • Create a Service
  • Clean up
• kustomize
  • Get ready
  • Deploy apps
  • Clean up
• HELM
  • Get ready
  • Create a chart with helm CLI
  • Deploy demo-api app with helm
  • Deploy realblog stack
  • Clean up
• Argo CD
  • Get ready
  • create argocd app
  • Clean up
• References

System Setup

---

1. install Docker CLI

   brew install docker

2. install hyperkit to be used as docker run time.

   brew install hyperkit

3. install [minikube](brew install minikube ) to be used as kubernetes cluster

   brew install minikube

4. configure minikube resources (optional)

   minikube config set cpus 6
   minikube config set memory 12g

5. start minikube

   minikube start  --driver=hyperkit --container-runtime=docker

   

6. verify minikube

   minikube kubectl get nodes

   !minkube get pods](./docs/minikube_get_po.png)

7. point terminal's Docker CLI to the Docker instance inside minikube

   eval $(minikube docker-env)

8. Optionally you can open minikube dashboard

   minikube dashboard

   

   It should open a dashboard UI in browser like follow:

   

9. Install helm

   brew install helm

10. Install Argo CD CLI

    brew install argocd

kubectl

---

Get ready

1. start minikube

   minikube start  --driver=hyperkit --container-runtime=docker

2. point terminal's Docker CLI to the Docker instance inside minikube

   eval $(minikube docker-env)

3. build demo app image

   cd apps/demo-api
   docker build -t demo-api .

   

Create a Deployment

1. Create demo app Deployment

   Create a Deployment that manages a Pod. The Pod runs a Container based on the provided Docker image. We can not set image pull policy on CLI and we want to use the local image, so we will create a simple config file to from CLI itself and add the parameter for image pull policy to "Never".

   Create a deployment file.

   cd ../ # if not on the root path
   cd kubectl

   kubectl create deployment demo-api --image=demo-api:latest --dry-run=client -o yaml > deployment.yaml

   

   Now Modify spec.template.spec.containers in deployment.yaml created.

   spec:
   	containers:
   	- image: demo-api:latest
   	name: demo-api
   	resources: {}

   and add imagePullPolicy: Never so that it looks like:

   spec:
   	containers:
   	- image: demo-api:latest
   	name: demo-api
   	resources: {}
   	imagePullPolicy: Never

   Apply the config file with kubectl

   kubectl apply -f deployment.yaml

   Output is similar to:

   kubectl apply -f deployment.yaml
   deployment.apps/demo-api created

2. View the Deployment:

   kubectl get deployments

   The output is similar to:

   NAME       READY   UP-TO-DATE   AVAILABLE   AGE
   demo-api   1/1     1            1           28s
   

3. View the Pod:

   kubectl get pods

   The output is similar to:

   NAME                        READY   STATUS    RESTARTS   AGE
   demo-api-7c7d9f4689-sbkns   1/1     Running   0          100s

4. View cluster events:

   kubectl get events

5. View the kubectl configuration:

   kubectl config view

Create a Service

By default, the Pod is only accessible by its internal IP address within the Kubernetes cluster. To make the demo-api Container accessible from outside.

1. Expose the Pod to the public internet using the kubectl expose command:

   kubectl expose deployment demo-api --type=LoadBalancer --port=3000

2. View the Service you created:

   kubectl get services

   The output is similar to:

   NAME         TYPE           CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE
   demo-api     LoadBalancer   10.101.236.39   <pending>     3000:30490/TCP   13s
   kubernetes   ClusterIP      10.96.0.1       <none>        443/TCP          21s

3. Run the following command to open the app:

   minikube service demo-api

   The output is similar to:

   |-----------|----------|-------------|----------------------------|
   | NAMESPACE |   NAME   | TARGET PORT |            URL             |
   |-----------|----------|-------------|----------------------------|
   | default   | demo-api |        3000 | http://192.168.106.3:30490 |
   |-----------|----------|-------------|----------------------------|
   🎉  Opening service default/demo-api in default browser...

   It should open the following page in the browser:

   

Clean up

1. Now you can clean up the resources you created in your cluster:

   kubectl delete service demo-api
   kubectl delete deployment demo-api

2. Optionally, stop the Minikube virtual machine (VM):

   minikube stop

3. Optionally, delete the Minikube VM:

   minikube delete

kustomize

---

In this we will deploy multiple services. To do so we will be using multiple config files for kubernetes and will manage the config with help of kustomize. This will deploy a proper backend, frontend and db instance to power up a full application stack and use it as we do in production. This example will use the realworld blog app API and UI example apps.

We will deploy following services:

1. blog-api: expressjs backend REST API server.
2. blog-ui: react UI app being served by a nginx server.
3. postgres: db for blog-api backend service.

Get ready

1. start minikube

   minikube start  --driver=hyperkit --container-runtime=docker

2. point terminal's Docker CLI to the Docker instance inside minikube

   eval $(minikube docker-env)

3. build blog-api app image

   cd apps/realblog/blog-api
   docker build -t blog-api .

   Output will be similar to:

   ~/dev/learn/kubernetes  cd apps/realblog/blog-api
   docker build -t blog-api .
   Sending build context to Docker daemon  2.048kB
   Step 1/10 : FROM node:16.15.0
   ---> 9d200cd667d5
   Step 2/10 : RUN mkdir -p /home/node/app && chown -R node:node /home/node/app
   ---> Using cache
   ---> 48145b89be5e
   Step 3/10 : WORKDIR /home/node
   ---> Using cache
   ---> 280c540f8d5c
   Step 4/10 : RUN git clone --depth 1 https://github.com/tanem/express-bookshelf-realworld-example-app.git app
   ---> Using cache
   ---> 34dd1b5c6ded
   Step 5/10 : RUN chown -R node:node /home/node/app
   ---> Using cache
   ---> d95cb606a0de
   Step 6/10 : WORKDIR /home/node/app
   ---> Using cache
   ---> 740cacc09bdd
   Step 7/10 : RUN npm i
   ---> Using cache
   ---> 7b86ce450a87
   Step 8/10 : EXPOSE 3000
   ---> Using cache
   ---> 1b4d3ba26c7b
   Step 9/10 : USER node
   ---> Using cache
   ---> 06c0b457b04a
   Step 10/10 : CMD [ "./bin/start.sh" ]
   ---> Using cache
   ---> 487c135295f6
   Successfully built 487c135295f6
   Successfully tagged blog-api:latest
   ``

4. build blog-ui app image

   cd apps/realblog/blog-ui
   docker build -t blog-ui .

   Output will be similar to:

   ~ cd apps/realblog/blog-ui
   ~ docker build -t blog-ui .
   Sending build context to Docker daemon   2.56kB
   Step 1/11 : FROM node:14.19.3 as base
   ---> f3ec39298d1b
   Step 2/11 : RUN mkdir -p /home/node/app && chown -R node:node /home/node/app
   ---> Using cache
   ---> 49cc9653ba42
   Step 3/11 : WORKDIR /home/node
   ---> Using cache
   ---> 8668cbb0d4c8
   Step 4/11 : RUN git clone --depth 1 https://github.com/angelguzmaning/ts-redux-react-realworld-example-app.git app
   ---> Using cache
   ---> 24326deaa442
   Step 5/11 : RUN chown -R node:node /home/node/app
   ---> Using cache
   ---> f0a11bcbee98
   Step 6/11 : WORKDIR /home/node/app
   ---> Using cache
   ---> 7b2bb3a27151
   Step 7/11 : RUN npm i
   ---> Using cache
   ---> bd859e464065
   Step 8/11 : RUN npm run build
   ---> Using cache
   ---> f2249c73479a
   Step 9/11 : USER node
   ---> Using cache
   ---> 9a1326890a11
   Step 10/11 : FROM nginx
   ---> 1403e55ab369
   Step 11/11 : COPY --from=base /home/node/app/build /usr/share/nginx/html
   ---> Using cache
   ---> 29b831cc3064
   Successfully built 29b831cc3064
   Successfully tagged blog-ui:latest

5. enable ingress plugin

   Ref: https://kubernetes.io/docs/concepts/services-networking/ingress/

   minikube addons enable ingress

6. add domain to hosts

   Get minikube IP

   minikube ip

   update your machine's hosts file

   sudo vi /etc/hosts

   Add the host realblog.local to the file and point it to minikube IP.

   Hosts should look like:

   127.0.0.1	localhost
   255.255.255.255	broadcasthost
   ::1             localhost
   
   192.168.106.3 realblog.local

Deploy apps

1. apply config with kustomize to kubectl

   cd kustomize/realblog
   kubectl apply -k ./

   Output will be similar to:

   service/realblog-api created
   service/realblog-postgres created
   service/realblog-ui created
   persistentvolumeclaim/postgres-pv-claim created
   deployment.apps/realblog-api created
   deployment.apps/realblog-postgres created
   deployment.apps/realblog-ui created
   ingress.networking.k8s.io/realblog-ingress created

2. verify deployment and services

   list deployments

   kubectl get deployments

   Output will be similar to:

   kubectl get deployments
   NAME                READY   UP-TO-DATE   AVAILABLE   AGE
   realblog-api        1/1     1            1           2m44s
   realblog-postgres   1/1     1            1           2m44s
   realblog-ui         1/1     1            1           2m44s

   list pods

   kubectl get pods

   Output will be similar to:

   NAME                                 READY   STATUS    RESTARTS   AGE
   realblog-api-785df47759-plwjw        1/1     Running   0          4m15s
   realblog-postgres-5967b7666c-5t8c4   1/1     Running   0          4m15s
   realblog-ui-6fc444cb95-zqcjt         1/1     Running   0          4m15s	```
   
   list services
   ```shell
   kubectl get services

   Output will be similar to:

   NAME                TYPE           CLUSTER-IP     EXTERNAL-IP   PORT(S)          AGE
   kubernetes          ClusterIP      10.96.0.1      <none>        443/TCP          12h
   realblog-api        LoadBalancer   10.99.28.2     <pending>     3000:30148/TCP   5m23s
   realblog-postgres   ClusterIP      None           <none>        5432/TCP         5m23s
   realblog-ui         LoadBalancer   10.99.96.128   <pending>     80:32187/TCP     5m23s

   list ingress

   kubectl get ingress

   Output will be similar to:

   NAME               CLASS   HOSTS            ADDRESS         PORTS   AGE
   realblog-ingress   nginx   realblog.local   192.168.106.3   80      6m21s

3. Use blog app

   open "http://realblog.local" in browser. A blogger site should open. Create a user and add some articles to test the app follow.

   

Clean up

1. Now you can clean up the resources you created in your cluster:

   Run the following command from kustomize/realblog:

   kubectl delete -k ./

2. Optionally, stop the Minikube virtual machine (VM):

   minikube stop

3. Optionally, delete the Minikube VM:

   minikube delete

HELM

We will learn this in two phases, first we will deploy the default nginx app and then our demo-api app, second we will deploy the complete realblog project with db, API and UI services and expose it with the ingress.

Get ready

1. start minikube

   minikube start  --driver=hyperkit --container-runtime=docker

2. point terminal's Docker CLI to the Docker instance inside minikube

   eval $(minikube docker-env)

3. build demo-api app image

   cd apps/demo-api
   docker build -t demo-api .
   cd ../../

Create a chart with helm CLI

1. switch to helm dir

   cd helm

2. create helm chart with helm CLI (default template)

   This command creates a directory "realblog" inside which it pusts charts for a service.

   helm create demo

3. explore helm chart created

   cd demo
   ls 

   Result should be similar to:

   Chart.yaml  charts      templates   values.yaml

4. install the chart

   helm install demo .

   Results should be similar to:

   NAME: demo
   LAST DEPLOYED: Tue Jan  3 19:46:54 2023
   NAMESPACE: default
   STATUS: deployed
   REVISION: 1
   NOTES:
   1. Get the application URL by running these commands:
   	export POD_NAME=$(kubectl get pods --namespace default -l "app.kubernetes.io/name=demo,app.kubernetes.io/instance=demo" -o jsonpath="{.items[0].metadata.name}")
   	export CONTAINER_PORT=$(kubectl get pod --namespace default $POD_NAME -o jsonpath="{.spec.containers[0].ports[0].containerPort}")
   	echo "Visit http://127.0.0.1:8080 to use your application"
   	kubectl --namespace default port-forward $POD_NAME 8080:$CONTAINER_PORT

5. expose the service to access from machine To access the app on http follow on screen instructions or run

   kubectl --namespace default port-forward deployment/demo 8080:80

   Result should be similar to:

   Forwarding from 127.0.0.1:8080 -> 80
   Forwarding from [::1]:8080 -> 80
   Handling connection for 8080
   Handling connection for 8080

6. verify on browser

   Open http://localhost:8080 in browser and you should be able to see a nginx welcome screen.

   

Deploy demo-api app with helm

1. switch to demo chart created in previous stage

   cd helm/demo		

2. update chart

   Update the image repository and tag to use demo-api image and latest tag in values.yaml file, to do so in the file helm/demo/values.yaml update following:

   image.repository : demo-api

   image.tag : latest

   service.port : 3000

3. upgrade the deployment

   helm upgrade demo .

   Result should be similar to:

   Release "demo" has been upgraded. Happy Helming!
   NAME: demo
   LAST DEPLOYED: Wed Jan  4 12:33:24 2023
   NAMESPACE: default
   STATUS: deployed
   REVISION: 3
   NOTES:
   1. Get the application URL by running these commands:
   	export POD_NAME=$(kubectl get pods --namespace default -l "app.kubernetes.io/name=demo,app.kubernetes.io/instance=demo" -o jsonpath="{.items[0].metadata.name}")
   	export CONTAINER_PORT=$(kubectl get pod --namespace default $POD_NAME -o jsonpath="{.spec.containers[0].ports[0].containerPort}")
   	echo "Visit http://127.0.0.1:8080 to use your application"
   	kubectl --namespace default port-forward $POD_NAME 8080:$CONTAINER_PORT

4. expose the service to access from machine To access the app on http follow on screen instructions or run

   kubectl --namespace default port-forward deployment/demo 8080:3000

   Result should be similar to:

   Forwarding from 127.0.0.1:8080 -> 3000
   Forwarding from [::1]:8080 -> 3000
   Handling connection for 8080
   Handling connection for 8080

5. verify on browser

   Open http://localhost:8080 in browser and you should be able to see express app.

   

6. delete deployments

   Delete the deployent to avoid confusion while trying next/other stages.

   helm uninstall demo --wait

   It should return :

   release "demo" uninstalled

Deploy realblog stack

1. start minikube

   minikube start  --driver=hyperkit --container-runtime=docker

2. point terminal's Docker CLI to the Docker instance inside minikube

   eval $(minikube docker-env)

3. build blog-api app image

   cd apps/realblog/blog-api
   docker build -t blog-api .

4. build blog-ui app image

   cd apps/realblog/blog-ui
   docker build -t blog-ui .

5. switch to helm charts directory for realblog

   cd helm/realblog

6. install charts

   helm install realblog . 

   Result should be similar to:

   NAME: realblog
   LAST DEPLOYED: Wed Jan  4 12:47:08 2023
   NAMESPACE: default
   STATUS: deployed
   REVISION: 1
   NOTES:
   1. Get the application URL by running these commands:
   	http://realblog.local/
   	http://realblog.local/api

7. Add cluster IP to local hosts entry for dns resolution

   Get minikube IP

   minikube ip

   update your machine's hosts file

   sudo vi /etc/hosts

   Add the host realblog.local to the file and point it to minikube IP.

   Hosts should look like:

   127.0.0.1	localhost
   255.255.255.255	broadcasthost
   ::1             localhost
   
   192.168.106.3 realblog.local

   In this the IP 192.168.106.3 is the IP of cluster node returned by command minikube ip

8. verify on browser

   Open http://realblog.local/ in browser and you should be able to see blog app UI.

   

Clean up

1. Now you can clean up the resources you created in your cluster:

   helm uninstall realblog --wait

2. Optionally, stop the Minikube virtual machine (VM):

   minikube stop

3. Optionally, delete the Minikube VM:

   minikube delete

Argo CD

Get ready

1. start minikube

   minikube start  --driver=hyperkit --container-runtime=docker

2. point terminal's Docker CLI to the Docker instance inside minikube

   eval $(minikube docker-env)

3. build blog-api app image

   cd apps/realblog/blog-api
   docker build -t blog-api .

4. build blog-ui app image

   cd apps/realblog/blog-ui
   docker build -t blog-ui .

5. add domain to hosts

   Get minikube IP

   minikube ip

   update your machine's hosts file

   sudo vi /etc/hosts

   Add the host realblog.local to the file and point it to minikube IP.

   Hosts should look like:

   127.0.0.1	localhost
   255.255.255.255	broadcasthost
   ::1             localhost
   
   192.168.106.3 realblog.local

   In this the IP 192.168.106.3 is the IP of cluster node returned by command minikube ip

6. Run argo CD

   kubectl create namespace argocd
   kubectl apply -n argocd -f https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install.yaml
   kubectl port-forward svc/argocd-server -n argocd 8080:443

   Results should be similar to:

   namespace/argocd created

   customresourcedefinition.apiextensions.k8s.io/applications.argoproj.io created
   customresourcedefinition.apiextensions.k8s.io/applicationsets.argoproj.io created
   customresourcedefinition.apiextensions.k8s.io/appprojects.argoproj.io created
   serviceaccount/argocd-application-controller created
   serviceaccount/argocd-applicationset-controller created
   serviceaccount/argocd-dex-server created
   serviceaccount/argocd-notifications-controller created
   serviceaccount/argocd-redis created
   serviceaccount/argocd-repo-server created
   serviceaccount/argocd-server created
   role.rbac.authorization.k8s.io/argocd-application-controller created
   role.rbac.authorization.k8s.io/argocd-applicationset-controller created
   role.rbac.authorization.k8s.io/argocd-dex-server created
   role.rbac.authorization.k8s.io/argocd-notifications-controller created
   role.rbac.authorization.k8s.io/argocd-server created
   clusterrole.rbac.authorization.k8s.io/argocd-application-controller created
   clusterrole.rbac.authorization.k8s.io/argocd-server created
   rolebinding.rbac.authorization.k8s.io/argocd-application-controller created
   rolebinding.rbac.authorization.k8s.io/argocd-applicationset-controller created
   rolebinding.rbac.authorization.k8s.io/argocd-dex-server created
   rolebinding.rbac.authorization.k8s.io/argocd-notifications-controller created
   rolebinding.rbac.authorization.k8s.io/argocd-redis created
   rolebinding.rbac.authorization.k8s.io/argocd-server created
   clusterrolebinding.rbac.authorization.k8s.io/argocd-application-controller created
   clusterrolebinding.rbac.authorization.k8s.io/argocd-server created
   configmap/argocd-cm created
   configmap/argocd-cmd-params-cm created
   configmap/argocd-gpg-keys-cm created
   configmap/argocd-notifications-cm created
   configmap/argocd-rbac-cm created
   configmap/argocd-ssh-known-hosts-cm created
   configmap/argocd-tls-certs-cm created
   secret/argocd-notifications-secret created
   secret/argocd-secret created
   service/argocd-applicationset-controller created
   service/argocd-dex-server created
   service/argocd-metrics created
   service/argocd-notifications-controller-metrics created
   service/argocd-redis created
   service/argocd-repo-server created
   service/argocd-server created
   service/argocd-server-metrics created
   deployment.apps/argocd-applicationset-controller created
   deployment.apps/argocd-dex-server created
   deployment.apps/argocd-notifications-controller created
   deployment.apps/argocd-redis created
   deployment.apps/argocd-repo-server created
   deployment.apps/argocd-server created
   statefulset.apps/argocd-application-controller created
   networkpolicy.networking.k8s.io/argocd-application-controller-network-policy created
   networkpolicy.networking.k8s.io/argocd-applicationset-controller-network-policy created
   networkpolicy.networking.k8s.io/argocd-dex-server-network-policy created
   networkpolicy.networking.k8s.io/argocd-notifications-controller-network-policy created
   networkpolicy.networking.k8s.io/argocd-redis-network-policy created
   networkpolicy.networking.k8s.io/argocd-repo-server-network-policy created
   networkpolicy.networking.k8s.io/argocd-server-network-policy created

   Forwarding from 127.0.0.1:8080 -> 8080
   Forwarding from [::1]:8080 -> 8080
   Handling connection for 8080
   Handling connection for 8080

7. Use Argo CD UI

   Open https://localhost:8080/ in your browser and you should see login page of the argocd.

   

   Login with username and password:

   Username is admin and password you can get from following command:

   kubectl -n argocd get secret argocd-initial-admin-secret -o jsonpath="{.data.password}" | base64 -d; echo

   After login you should see the app explorer page like follow:

   

8. get CLI ready

   You can create app from UI also but this guide will use CLI to create the app.

   • open a new terminal as the cuurent one is used to port farward argo.
   • Login on argocd CLI

   argocd login localhost:8080

   the result should be similar to:

   WARNING: server certificate had error: x509: “Argo CD” certificate is not trusted. Proceed insecurely (y/n)? y
   Username: admin
   Password:
   'admin:login' logged in successfully
   Context 'localhost:8080' updated

   use the same username and password used to login on UI.

create argocd app

In this we will use the same helm charts used for deployment of services and images created in set up section to create deployment through argocd.

1. create app with CLI

   argocd app create realblog --repo https://github.com/satyamyadav/kubernetes-101.git --path helm/realblog --dest-server https://kubernetes.default.svc --dest-namespace default

2. verify on browser

   open https://localhost:8080/applications/argocd/realblog?view=tree&resource=kind%3ADeployment It should show the deployments.

   

   Sync the app if it is not synced.

3. verify app

   open http://realblog.local you should see the blog app UI home page.

   

Clean up

1. Now you can clean up the resources you created in your cluster: you can delete the app from argocd UI also.

   argocd app delete realblog

2. Optionally, stop the Minikube virtual machine (VM):

   minikube stop

3. Optionally, delete the Minikube VM:

   minikube delete

References

• Kubernetes: https://kubernetes.io/docs/tutorials/hello-minikube/
• Helm: https://helm.sh/
• ArgoCD: https://argo-cd.readthedocs.io/en/stable/getting_started/