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Helm Chart Templates for Node.js in Kubernetes

This project provides template Helm Charts for deploying a Node.js web application into any Kubernetes based cloud.

The templates require your application to built into a Docker image. The Docker Templates project provides assistance in creating an image for your application.

This project provides the following files:

File Description
/chart/nodeserver/Chart.yaml The definition file for your application
/chart/nodeserver/values.yaml Configurable values that are inserted into the following template files
/chart/nodeserver/templates/basedeployment.yaml Template to configure your application deployment.
/chart/nodeserver/templates/deployment.yaml Template to configure your application deployment.
/chart/nodeserver/templates/service.yaml Template to configure your application deployment.
/chart/nodeserver/templates/hpa.yaml Template to configure your application deployment.
/chart/nodeserver/templates/istio.yaml Template to configure your application deployment.
/chart/nodeserver/templates/NOTES.txt Helper to enable locating your application IP and PORT

In order to use these template files, copy the files from this project into your application directory. You should only need to edit the Chart.yaml and values.yaml files.

Prerequisites

Using the template Helm charts assumes the following pre-requisites are complete:

  1. You have a Kubernetes cluster
    This could be one hosted by a cloud provider or running locally, for example using Minikube

  2. You have kubectl installed and configured for your cluster
    The Kuberenetes command line tool, kubectl, is used to view and control your Kubernetes cluster.

  3. You have the Helm command line and Tiller backend installed
    Helm and Tiller provide the command line tool and backend service for deploying your application using the Helm chart. These charts are compatible with Helm v2 and v3

  4. You have created and published a Docker image for your application
    The Docker Template project provides guidance on building a run image for your application and publishing it to the DockerHub registry.

  5. Your application has a "health" endpoint
    This allows Kubernetes to restart your application if it fails or becomes unresponsive. The Health Connect middleware can be used to add a health endpoint.

Adding the Chart to your Application

In order to add Helm Charts to your application, copy the charts directory from this project into your application's root directory.

You then need to make a single change before the charts are usable: to set the image.repository for your application.

Setting the image.repository parameter

In order to change the image.repository parameter, open the charts/nodeserver/values.yaml file and change the following entry:

image:
  repository: <namespace>/nodeserver

to set <namespace> to your namespace on DockerHub where you published your application as nodeserver.

Configuring the Chart for your Application

The following table lists the configurable parameters of the template Helm chart and their default values.

Parameter Description Default
image.repository image repository <namespace>/nodeserver
image.tag Image tag latest
image.pullPolicy Image pull policy Always
livenessProbe Configuration for any liveness probe provided YAML object of liveness probe. See Liveness and Readiness Probes
readinessProbe Configuration provided for any liveness probe provided YAML object of readiness probe. See Liveness and Readiness Probes
service.name Kubernetes service name Node
service.type Kubernetes service type exposing port NodePort
service.port TCP Port for this service 3000
resources.limits.memory Memory resource limits 128m
resources.limits.cpu CPU resource limits 100m

Liveness and Readiness Probes

With the default configuration, no liveness or readiness is enabled. This means that the container is considered healthy as long as its main process is running, otherwise it's considered a failure.

Optionally, you add configurations for readiness and liveness probes by configuring image.readinessProbe and image.livenessProbe parameters, respectively. Example configuration is provided in the values.yaml file.

The initialDelaySeconds defines how long to wait before performing the first probe. Default value for readiness probe is 2 seconds and for liveness probe is 20 seconds. You should set appropriate values for your container, if necessary, to ensure that the readiness and liveness probes don’t interfere with each other. Otherwise, the liveness probe might continuously restart the pod and the pod will never be marked as ready.

More information about configuring liveness and readiness probes can be found here

Using the Chart to deploy your Application to Kubernetes

In order to use the Helm chart to deploy and verify your application in Kubernetes, run the following commands:

  1. From the directory containing Chart.yaml, run:

Helm v2

helm install --name nodeserver .

Helm v3

helm install nodeserver .

This deploys and runs your application in Kubernetes, and prints the following text to the console:

Congratulations, you have deployed your Node.js Application to Kubernetes using Helm!

To verify your application is running, run the following two commands to set the SAMPLE_NODE_PORT and SAMPLE_NODE_IP environment variables to the location of your application:

export SAMPLE_NODE_PORT=$(kubectl get --namespace default -o jsonpath="{.spec.ports[0].nodePort}" services nodeserver-service)
export SAMPLE_NODE_IP=$(kubectl get nodes --namespace default -o jsonpath="{.items[0].status.addresses[0].address}")

And then open your web browser to http://${SAMPLE_NODE_IP}:${SAMPLE_NODE_PORT} from the command line, eg:

open http://${SAMPLE_NODE_IP}:${SAMPLE_NODE_PORT}
  1. Copy, paste and run the export lines printed to the console eg:
export SAMPLE_NODE_PORT=$(kubectl get --namespace default -o jsonpath="{.spec.ports[0].nodePort}" services nodeserver-service)
export SAMPLE_NODE_IP=$(kubectl get nodes --namespace default -o jsonpath="{.items[0].status.addresses[0].address}")
  1. Open a browser to view your application:
    Open your browser to http://${SAMPLE_NODE_IP}:${SAMPLE_NODE_PORT} from the command line using:
open http://${SAMPLE_NODE_IP}:${SAMPLE_NODE_PORT}

You application should now be visible in your browser.

Uninstalling your Application

If you installed your application with:

Helm v2

helm install --name nodeserver .

then you can:

  • Find the deployment using helm list --all and searching for an entry with the chart name "nodeserver".
  • Remove the application with helm delete --purge nodeserver.

Helm v3

helm install nodeserver .

then you can:

  • Find the deployment using helm list --all and searching for an entry with the chart name "nodeserver".
  • Remove the application with helm uninstall nodeserver.