Hello from foobar and Hello from {pod name}

Project to implement a task to test Docker, Jenkinsfile, Java, Kubernetes, Gradle

Prerequisites

JDK 8+
Gradle
Docker

Getting started

Get project from GitHub:

git clone https://github.com/hivp/hellofrom.git

Go to the project folder:

cd hellofrom

Building the project with Gradle

To build the project and generate the Jar, just use:

./gradlew build

It generates a fat-jar in the build/libs directory.

Build the project using the Jenkinsfile

A Jenkinsfile is provided to build the app.

Stages added:

Get source code from github
Build app with gradle
Generate docker image in the local docker registry

The stage for uploading the docker image to Docker Hub is commented. In a normal environment, this stage should be replaced by your own registry.

The docker image is already in Docker Hub https://hub.docker.com/r/hugovarela/hellofrom/

Just use the Jenkinsfile in a Jenkins Job as you desire.

Running the project with Gradle

Once you have retrieved the project, you can check that everything works with:

./gradlew build test run

The command compiles the project and runs the tests, then it launches the application. Open your browser to http://localhost:8080 or execute:

curl http://localhost:8080

This will show:

Hello from foobar

You can just run without test:

./gradlew run

Generate Docker image

This will generate a docker image in the local Docker registry

docker build -t hellofrom:1.0 .

docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
hellofrom           1.0                 df09fececfca        4 seconds ago       73.9MB

This image can be uploaded to Docker Hub:

docker tag hellofrom:1.0 hugovarela/hellofrom:1.0
docker push hugovarela/hellofrom:1.0

docker images
REPOSITORY             TAG                 IMAGE ID            CREATED             SIZE
hugovarela/hellofrom   1.0                 df09fececfca        22 minutes ago      73.9MB
hellofrom              1.0                 df09fececfca        22 minutes ago      73.9MB

Using Docker Hub is just for testing purposes for this task. You can use your own docker registry.

Testing the docker image

Once the hellofrom:1.0 image is in the local registry, it can be started:

docker run -t -i -p 8080:8080 hellofrom:1.0

curl http://localhost:8080
(example output) Hello from foobar

Testing the image in Kubernetes with minikube ip

For this task, we will use Docker Hub to get the image, it is in deployment.yml (image: hugovarela/hellofrom:1.0), you can use your own registry to get the image, just change it in the file. The docker image is already in Docker Hub https://hub.docker.com/r/hugovarela/hellofrom/

The image can be tested using Minikube (assuming Minikube service is running locally).

kubectl create -f deployment.yml

The Service is configured to run in port: 30397 (nodePort: 30397), so the HelloFrom can be tested using the Minikube IP. HelloFrom app will respond with the pod name when running in Kubernetes and "Hello from foobar" without Kubernetes. Check HelloFrom.java and deployment.yml.

curl http://$(minikube ip):30397
Hello from "pod name here"

Testing with an External URL with Ingress

For example purposes, follow this steps to enable HelloFrom app with Ingress:

Get minikube ip

minikube ip ----> example output: 192.168.99.100

Add that IP and a hostname in /etc/hosts

192.168.99.100 testhello

Enable Ingress in minikube, if not enabled

minikube addons enable ingress

Create ingress with the ingress.yml generated for this task:

kubectl create -f ingress.yml

Finally, use the host added to /etc/hosts to test HelloFrom

curl http://testhello/hellofrom

(example output) Hello from hellofrom-56675f664c-qqbzz