How to Set up a Local K8s Cluster Using KinD

Use Case

The current cloud era is dominated heavily by Kubernetes (k8s). While the DevOps team manages App lifecycle (deploy, scale, upgrade, downgrade, etc.), the App developer needs to build a similar environment locally. So before shipping the App, developer is required to ensure DevOps lifecycle is not impacted by any of the changes s/he makes.

So it is very much necessary for a Developer to have a local k8s cluster for testing. In short, this blog post demonstrates the following flow.

Assumption

• You have docker, kubectl and KinD installed on your host.
• You have go version go1.20.3 installed on the host. However, older version should work too.
• This complete setup is build on Ubuntu 22.04.2 host. If you are using another OS/platform, then you might need to modify the commands accordingly.

Let Start...

Prerequisite Setup

Clone the repo

[~]# git clone https://github.com/simplyatul/godevsetup.git
[~]# cd godevsetup

Now using KinD, create local k8s cluster with a control plane node and two worker nodes.

[~/godevsetup]# kind create cluster --config ./kind-local-k8s-cluster-baremin.yaml --name local-dev
Creating cluster "local-dev" ...
 ✓ Ensuring node image (kindest/node:v1.26.3) 🖼
 ✓ Preparing nodes 📦 📦 📦  
 ✓ Writing configuration 📜 
 ✓ Starting control-plane 🕹️ 
 ✓ Installing CNI 🔌 
 ✓ Installing StorageClass 💾 
 ✓ Joining worker nodes 🚜 
Set kubectl context to "kind-local-dev"
You can now use your cluster with:

kubectl cluster-info --context kind-local-dev

Have a question, bug, or feature request? Let us know! https://kind.sigs.k8s.io/#community 🙂

You can see that the control plane node and worker nodes are installed and running as separate containers.

[~/godevsetup]# docker ps -a
CONTAINER ID   IMAGE                  COMMAND                  CREATED              STATUS          PORTS                       NAMES
9d2f27169e21   kindest/node:v1.26.3   "/usr/local/bin/entr…"   About a minute ago   Up 47 seconds                               local-dev-worker2
2b198d465d81   kindest/node:v1.26.3   "/usr/local/bin/entr…"   About a minute ago   Up 47 seconds                               local-dev-worker
96f3a760a02a   kindest/node:v1.26.3   "/usr/local/bin/entr…"   About a minute ago   Up 47 seconds   127.0.0.1:33519->6443/tcp   local-dev-control-plane

Step 1 - App Development

I have written a simple App in Go. You can do this in any language of your choice. The App exposes a ReST API on port 8080 and returns the hostname. Check the GitHub code. You can run the App locally using go run main.go and then hit the following command from another terminal.

[~]# curl localhost:8080
Hostname: ubuntu-jammy

Once you complete the coding, commit it. Optionally, you can push it to the remote repo as well.

Step 2 - Containerize The App

Build the docker image

[~/godevsetup]# docker build -t godevsetup:latest .

Run it locally and check once

[~/godevsetup]# docker run --rm --name godevsetup -p 8080:8080 godevsetup:latest

# From another terminal
[~/godevsetup]# curl localhost:8080
Hostname: 48143ca71c90

Step 3 - Push Image Into Your Cluster

Here we will push the container image onto the cluster nodes created by KinD

[~/godevsetup]# kind load docker-image godevsetup:latest --name local-dev
Image: "godevsetup:latest" with ID "sha256:aa7dbb2842050be8c1635ff117ef938e3cf7fb0c32d56d9a7fe16ca73fda0f62" not yet present on node "local-dev-worker2", loading...
Image: "godevsetup:latest" with ID "sha256:aa7dbb2842050be8c1635ff117ef938e3cf7fb0c32d56d9a7fe16ca73fda0f62" not yet present on node "local-dev-worker", loading...
Image: "godevsetup:latest" with ID "sha256:aa7dbb2842050be8c1635ff117ef938e3cf7fb0c32d56d9a7fe16ca73fda0f62" not yet present on node "local-dev-control-plane", loading...

You can inspect image is loaded

[~/godevsetup]# docker exec local-dev-control-plane crictl images
IMAGE                                                     TAG                 IMAGE ID            SIZE
docker.io/library/godevsetup                              latest              aa7dbb2842050       869MB
registry.k8s.io/etcd                                      3.5.6-0             fce326961ae2d       103MB
registry.k8s.io/kube-apiserver                            v1.26.3             801fc1f38fa6c       80.4MB
registry.k8s.io/kube-controller-manager                   v1.26.3             cb77c367deebf       68.5MB
registry.k8s.io/pause                                     3.7                 221177c6082a8       311kB
docker.io/kindest/kindnetd:v20230330-48f316cd             <none>              a329ae3c2c52f       27.7MB
docker.io/kindest/local-path-helper:v20230330-48f316cd    <none>              37af659db0ba1       3.05MB
registry.k8s.io/coredns/coredns                           v1.9.3              5185b96f0becf       14.8MB
docker.io/kindest/local-path-provisioner:v0.0.23-kind.0   <none>              c408b2276bb76       18.7MB
registry.k8s.io/kube-proxy                                v1.26.3             eb3079d47a23a       67.2MB
registry.k8s.io/kube-scheduler                            v1.26.3             dec886d066492       57.8MB
 

Step 4 - Deploy On Local K8s Cluster

I have created a Nodeport Service along with the deployment. Check the yaml file. Create the Service and the deployment.

[~/godevsetup]# kubectl apply -f godevsetup-nodeport.yaml
deployment.apps/godevsetup created
service/godevsetup-nodeport created 

You can check the Service and pods are created

[~/godevsetup]# kubectl get all
NAME                              READY   STATUS    RESTARTS   AGE
pod/godevsetup-78fbdfb985-4tmz2   1/1     Running   0          3m59s
pod/godevsetup-78fbdfb985-frl2d   1/1     Running   0          3m59s
pod/godevsetup-78fbdfb985-x77g4   1/1     Running   0          3m59s

NAME                          TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE
service/godevsetup-nodeport   NodePort    10.96.245.170   <none>        9090:30123/TCP   3m59s
service/kubernetes            ClusterIP   10.96.0.1       <none>        443/TCP          52m

NAME                         READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/godevsetup   3/3     3            3           3m59s

NAME                                    DESIRED   CURRENT   READY   AGE
replicaset.apps/godevsetup-78fbdfb985   3         3         3       3m59s

You can also observe the App pods are created inside the worker nodes

[~/godevsetup]# docker exec local-dev-worker crictl ps
CONTAINER           IMAGE               CREATED             STATE               NAME                     ATTEMPT             POD ID              POD
a310b2cf0201d       aa7dbb2842050       5 minutes ago       Running             godevsetup               0                   66781797eb650       godevsetup-78fbdfb985-frl2d
fea54fa36f629       c408b2276bb76       54 minutes ago      Running             local-path-provisioner   0                   d03b938684afd       local-path-provisioner-75f5b54ffd-k7xfb
b11289f372caf       5185b96f0becf       54 minutes ago      Running             coredns                  0                   0b51dcb843021       coredns-787d4945fb-wqxst
ee14e1dc8ff83       5185b96f0becf       54 minutes ago      Running             coredns                  0                   e7a1e535bb183       coredns-787d4945fb-g7xnq
99a540c5658fb       a329ae3c2c52f       54 minutes ago      Running             kindnet-cni              0                   eb134c7507011       kindnet-gmzxc
aaebc183b9f6a       eb3079d47a23a       54 minutes ago      Running             kube-proxy               0                   a7b50875a469f       kube-proxy-6wj5v

[~/godevsetup]# docker exec local-dev-worker2 crictl ps
CONTAINER           IMAGE               CREATED             STATE               NAME                ATTEMPT             POD ID              POD
b2d32e5b552f7       aa7dbb2842050       5 minutes ago       Running             godevsetup          0                   872cff6cf3ea3       godevsetup-78fbdfb985-4tmz2
9ae704f8c8669       aa7dbb2842050       5 minutes ago       Running             godevsetup          0                   e186f3ccda549       godevsetup-78fbdfb985-x77g4
79013566e33e8       a329ae3c2c52f       54 minutes ago      Running             kindnet-cni         0                   959abab06b391       kindnet-tg2jl
0611eaced1aad       eb3079d47a23a       54 minutes ago      Running             kube-proxy          0                   49477d56a66c8       kube-proxy-96f5x

Step 5 - Verify The Functionally

Since we have created a NodePort Service, we can access the service using Node’s IP

First, identify the Node IPs

[~/godevsetup]# kubectl get nodes -o wide
NAME                      STATUS   ROLES           AGE   VERSION   INTERNAL-IP   EXTERNAL-IP   OS-IMAGE             KERNEL-VERSION      CONTAINER-RUNTIME
local-dev-control-plane   Ready    control-plane   58m   v1.26.3   172.18.0.4    <none>        Ubuntu 22.04.2 LTS   5.15.0-72-generic   containerd://1.6.19-46-g941215f49
local-dev-worker          Ready    <none>          57m   v1.26.3   172.18.0.2    <none>        Ubuntu 22.04.2 LTS   5.15.0-72-generic   containerd://1.6.19-46-g941215f49
local-dev-worker2         Ready    <none>          57m   v1.26.3   172.18.0.3    <none>        Ubuntu 22.04.2 LTS   5.15.0-72-generic   containerd://1.6.19-46-g941215f49

The INTERNAL-IP is the IP of the worker node. Now access the API’s ReST endpoint using any of the Node’s IP and Port (Port is mentioned as nodePort: 30123 in our yaml file)

[~/godevsetup]# curl 172.18.0.4:30123
Hostname: godevsetup-78fbdfb985-frl2d

[~/godevsetup]# curl 172.18.0.2:30123
Hostname: godevsetup-78fbdfb985-frl2d

[~/godevsetup]# curl 172.18.0.3:30123
Hostname: godevsetup-78fbdfb985-4tmz2

Cool.. We are done. Now if you want to Enhance (or Bug-fix) your App, restart from Step 1. But before that, remove the Service and Deployment.

[~/godevsetup]# kubectl delete -f godevsetup-nodeport.yaml 
deployment.apps "godevsetup" deleted
service "godevsetup-nodeport" deleted

Sign Off…

This blog covers how to set up a local k8s cluster using KinD. And how can we leverage it for the App deployment and testing.

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