k8s ready Springboot template

This template is a preconfigured, scalable Springboot project with one minimal initial controller, ready to be deployed to Kubernetes. A single Gradle task outputs a finalised docker image that can be directly uploaded to an image registry of your choice. The image can directly be deployed with the preconfigured Deployment, Service and Ingress in the k8sready-springboot.yaml file.

This was tested with a kind cluster for simplicity's sake. Kind is a CNCF certified compliant Kubernetes installer. With some additional GitHub actions for example, this will perfectly integrate with many pipelines.

Features

Compilation Process

This Template provides a 'double stage docker image-creation' process. The final image is compiled in a clean Docker gradle environment during stage one of the Dockerfile. In the second stage, the clean java-executable is copied to an OpenJDK 17 container. That Container can e.g. be Deployed on a Kubernetes environment, or you can do basically anything else you can do with a container these days.

Gradle

All local tasks are grouped by the spring local group. Kubernetes related tasks are grouped by the k8s group

This template defines gradle commands for:

• Development runs: runSpringDev
• production runs: runSpringProd
• testing runs: testSpring
• Full Docker build: buildDockerImage

With the provided tasks, you can easily build a task to deploy directly to your own k8s.

Kubernetes

Also provided is a preconfigured Service, an Ingress and a Deployment to get you started. If you're using OpenShift for example you will need to replace the Ingress component with a Route, but you probably know that.

Database

You can add your Production Database in application.properties since that configuration will apply to production use. An extra database for testing can go into application-test.properties. One for development into application-dev.properties

Testing

Since springboot provides us with a variety of tests illustrated here I decided to provide some examples of HttpRequestTest and HttpRequestMockTest under ./src/test.

Env dependant values

In application.properties, I added an example value.depending.on.environment of a configuration value that holds different values per environment. An example of how you use that in Java is provided in the main spring class SpringKubernetesApplication using the @Value and @PostConstruct decorators. If you don't like it, you can just remove it entirely from the two mentioned locations.

tl;dr features

• Double Stage Docker image creation
• Compiled in an extra gradle container as Stage 1
• clean java-executable in OpenJDK 17 container as Stage 2
• Gradle commands for development, production & testing
• Preconfigured Service, Ingress and Deployment for Kubernetes (adapt the ingress for openshift)
• Custom Testing database if needed
• Predefined example tests illustrating different testing techniques (HttpRequestTest, HttpRequestMockTest)
• Environment dependant values

Usage

This part is very straightforward:

• Replace the name k8sreadyspringboot everywhere
• Adapt the value.depending.on.environment under application.properties
• Run your first gradle command, for example gradle runSpringProd (that's locally)
• Continue with the template as you like
• Don't forget to read the Pitfalls first

Pitfalls

1. Version number needs to be changed in 3 files: (commented)

   • build.gradle version attribute
   • Dockerfile ARTIFACT_NAME variable
   • Kubernetes Yaml in Deployment

2. Server Port needs to be changed in 3 Locations: (commented)

   • default application.properties server.port attribute
   • Kubernetes Yaml in Service and Ingress
   • Dockerfile under Expose

License

The project is licensed under the MIT license.

Maintainer

Current maintainer and owner: TheCoder777

Cheers!