Deploy nodeJS app to kubernetes cluster with helm

In this article, we attempt to deploy a nodeJS app to kubenetes cluster using helm.

helm: the package manager for kubernetes

I am using helm version 3.6.3 as shown below.

$ helm version
version.BuildInfo{Version:”v3.6.3", GitCommit:”d506314abfb5d21419df8c7e7e68012379db2354", GitTreeState:”clean”, GoVersion:”go1.16.5"}

1. Create a nodeJS app

To demonstrate, i create a simple nodeJS app, as shown below.

GitHub - victoryeo/myprog: nodejs app with docker, k8s yaml, helm chart

2. Dockerise the nodeJS app

FROM node:16.13.0 AS builder
WORKDIR /dist
COPY ./package.json ./
COPY ./package-lock.json ./
RUN npm ci
COPY . .
RUN npm run build
FROM node:16.13-alpine
WORKDIR /dist

The explanation of the Dockerfile is covered in here.

3. Setup a kubernetes cluster and connect to the cluster

We can use AWS EKS or Google GKE user interface to setup the kubernetes cluster. Alternatively, we can use terraform as well. Then we use the following command to connect our local environment to the cluster.

For AWS:

aws eks --region us-west-2 update-kubeconfig --name my-cluster

For GKE:

gcloud container clusters get-credentials my-cluster --zone us-east1 --project <proj_name>

4. Create helm chart

Run the command below to create helm chart files

helm create helmchart

5. Modify the helm chart files

In values.yaml, update the repository value:

image:
  repository: victoryeo00/myprog
  pullPolicy: IfNotPresent
  # Overrides the image tag whose default is the chart appVersion.
  tag: latest

and port value and type value:

service:
  type: LoadBalancer 
  port: 4002
  targetPort: 4002

In templates/service.yaml, update type and ports value

spec:
  type: {{ .Values.service.type }}
  ports:
    - port: {{ .Values.service.port }}
      targetPort: {{ .Values.service.targetPort }}
      protocol: TCP

In templates/deployment.yaml, update container port value

ports:
  - containerPort: 4002

6. Install the helm chart

Run the helm command below:

helm install myprog helmchart/

7. Check k8s pod and service status

$ kubectl get svc
NAME       TYPE      CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 172.20.0.1 <none>     443/TCP  24d
myprog LoadBalancer 172.20.242.168 a492a18.us-east-1.elb.amazonaws.com 4002:31599/TCP 15s

and

$ kubectl get pod
NAME                    READY STATUS   RESTARTS AGE
myprog-694c58864d-qmrms 1/1   Running  0    43s

8. Using curl command to test

In another terminal, run

$ curl http://a492a18.us-east 1.elb.amazonaws.com:4002/api/v1/healthz
healthy

That’s it. It works.

The helm chart files are available at:

https://github.com/victoryeo/myprog/tree/master/helmchart

Note:

In kubectl describe pod , i was getting this warning in pod (from kubectl get pod):

Readiness probe failed: Get “http://10.20.71.55:4002/api/v1/healthz": dial tcp 10.20.71.55:4002: connect: connection refused

To solve it, in templates/deployment.yaml, add initialDelaySeconds, update the path and port number.

livenessProbe:
  httpGet:
    path: /api/v1/healthz
    port: 4002
    initialDelaySeconds: 4
readinessProbe:
  httpGet:
    path: /api/v1/healthz
    port: 4002
    initialDelaySeconds: 4