bitnami-containers/bitnami/node/example

Example Application

TL;DR

$ kubectl create -f https://raw.githubusercontent.com/bitnami/bitnami-docker-node/master/example/kubernetes.yml

Introduction

This example demostrates the use of the bitnami/node image to create a production build of your node application.

For demonstration purposes we'll bootstrap a ExpressJS application, build a image with the tag bitnami/node-example and deploy it on a Kubernetes cluster.

Generate the application

The example application is an ExpressJS application bootstrapped using express-generator.

$ express --git --css less example/

Build and Test

To build a production Docker image of our application we'll use the bitnami/node:6-prod image, which is a production build of the Bitnami Node Image optimized for size.

FROM bitnami/node:6 as builder
ENV NODE_ENV="production"
COPY . /app
WORKDIR /app
RUN npm install

FROM bitnami/node:6-prod
ENV NODE_ENV="production"
COPY --from=builder /app /app
WORKDIR /app
EXPOSE 3000
CMD ["npm", "start"]

The Dockerfile consists of two build stages. The first stage uses the development image, bitnami/node:6, to copy the application source and install the required application modules using npm install. The NODE_ENV environment variable is defined so that npm install only installs the application modules that are required in production executions.

The second stage uses the production image, bitnami/node:6-prod, and copies over the application source and the installed modules from the previous stage. This creates a minimal Docker image that only consists of the application source, node modules and the node runtime.

To build the Docker image, execute the command:

$ docker build -t bitnami/node-example:0.0.1 example/

Since the bitnami/node:6-prod image is optimized for production deployments it does not include any packages that would bloat the image.

$ docker image ls
REPOSITORY                          TAG                    IMAGE ID            CREATED             SIZE
bitnami/node-example                0.0.1                  0d43bbca1cd2        22 seconds ago      193MB

You can now launch and test the image locally.

$ docker run -it --rm -p 3000:3000 bitnami/node-example:0.0.1

> example@0.0.1 start /app
> node ./bin/www

Finally, push the image to the Docker registry

$ docker push bitnami/node-example:0.0.1

Deployment

The kubernetes.yml file from the example/ folder can be used to deploy our bitnami/node-example:0.0.1 image to a Kubernetes cluster.

Simply download the Kubernetes manifest and create the Kubernetes resources described in the manifest using the command:

$ kubectl create -f kubernetes.yml
ingress "example-ingress" created
service "example-svc" created
configmap "example-configmap" created
persistentvolumeclaim "example-data-pvc" created
deployment "example-deployment" created

From the output of the above command you will notice that we create the following resources:

• Ingress
• Service
• Volume
  • ConfigMap
  • PersistentVolumeClaim
• Deployment

Note

Our example application is stateless and does not store any data or does not require any user configurations. As such we do not need to create the ConfigMap or PersistentVolumeClaim resources. Our kubernetes.yml creates these resources strictly to demostrate how they are defined in the manifest.

Accessing the application

Typically in production you would access the application via a Ingress controller. Our kubernetes.yml already defines a Ingress resource. Please refer to the Ingress documentation to learn how to deploy an ingress controller in your cluster.

Hint

https://kubeapps.com/charts/stable/nginx-ingress

The following are alternate ways of accessing the application, typically used during application development and testing.

Since the service example-svc is defined to be of type NodePort, we can set up port forwarding to access our web application like so:

$ kubectl port-forward $(kubectl get pods -l app=example -o jsonpath="{ .items[0].metadata.name }") 3000:3000

The command forwards the local port 3000 to port 3000 of the Pod container. You can access the application by visiting the http://localhost:3000.

Note:

If your using minikube, you can access the application by simply executing the following command:

$ minikube service example-svc

Health Checks

The kubernetes.yml manifest defines default probes to check the health of the application. For our application we are simply probing if the application is responsive to queries on the root resource.

You application can define a route, such as the commonly used /healthz, that reports the application status and use that route in the health probes.