Test your R deployment

Table of contents

Prerequisites

Complete all the previous sections of this guide, starting with Containerize a R application.
Turn on Kubernetes in Docker Desktop.

In this section, you'll learn how to use Docker Desktop to deploy your application to a fully-featured Kubernetes environment on your development machine. This allows you to test and debug your workloads on Kubernetes locally before deploying.

Create a Kubernetes YAML file

In your r-docker-dev directory, create a file named docker-r-kubernetes.yaml. Open the file in an IDE or text editor and add the following contents. Replace DOCKER_USERNAME/REPO_NAME with your Docker username and the name of the repository that you created in Configure CI/CD for your R application.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: docker-r-demo
  namespace: default
spec:
  replicas: 1
  selector:
    matchLabels:
      service: shiny
  template:
    metadata:
      labels:
        service: shiny
    spec:
      containers:
        - name: shiny-service
          image: DOCKER_USERNAME/REPO_NAME
          imagePullPolicy: Always
          env:
            - name: POSTGRES_PASSWORD
              value: mysecretpassword
---
apiVersion: v1
kind: Service
metadata:
  name: service-entrypoint
  namespace: default
spec:
  type: NodePort
  selector:
    service: shiny
  ports:
    - port: 3838
      targetPort: 3838
      nodePort: 30001

In this Kubernetes YAML file, there are two objects, separated by the ---:

A Deployment, describing a scalable group of identical pods. In this case, you'll get just one replica, or copy of your pod. That pod, which is described under template, has just one container in it. The container is created from the image built by GitHub Actions in Configure CI/CD for your R application.
A NodePort service, which will route traffic from port 30001 on your host to port 3838 inside the pods it routes to, allowing you to reach your app from the network.

To learn more about Kubernetes objects, see the Kubernetes documentation.

Deploy and check your application

In a terminal, navigate to r-docker-dev and deploy your application to Kubernetes.
$ kubectl apply -f docker-r-kubernetes.yaml
You should see output that looks like the following, indicating your Kubernetes objects were created successfully.
deployment.apps/docker-r-demo created service/service-entrypoint created

Make sure everything worked by listing your deployments.

$ kubectl get deployments

Your deployment should be listed as follows:

NAME                 READY   UP-TO-DATE   AVAILABLE   AGE
docker-r-demo   1/1     1            1           15s

This indicates all one of the pods you asked for in your YAML are up and running. Do the same check for your services.

$ kubectl get services

You should get output like the following.

NAME                 TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE
kubernetes           ClusterIP   10.96.0.1       <none>        443/TCP          23h
service-entrypoint   NodePort    10.99.128.230   <none>        3838:30001/TCP   75s

In addition to the default kubernetes service, you can see your service-entrypoint service, accepting traffic on port 30001/TCP.

In a browser, visit the following address. Note that a database was not deployed in this example.
http://localhost:30001/
Run the following command to tear down your application.
$ kubectl delete -f docker-r-kubernetes.yaml

Summary

In this section, you learned how to use Docker Desktop to deploy your application to a fully-featured Kubernetes environment on your development machine.

Related information:

Test your R deployment

Prerequisites

Overview

Create a Kubernetes YAML file

Deploy and check your application

Summary