Spring PetClinic Sample Application

Understanding the Spring Petclinic application with a few diagrams

See the presentation here

Running petclinic locally

Petclinic is a Spring Boot application built using Maven. You can build a jar file and run it from the command line:

git clone https://github.com/spring-projects/spring-petclinic.git
cd spring-petclinic
./mvnw package
java -jar target/*.jar

You can then access petclinic here: http://localhost:8080/

Or you can run it from Maven directly using the Spring Boot Maven plugin. If you do this it will pick up changes that you make in the project immediately (changes to Java source files require a compile as well - most people use an IDE for this):

./mvnw spring-boot:run

In case you find a bug/suggested improvement for Spring Petclinic

Our issue tracker is available here: https://github.com/spring-projects/spring-petclinic/issues

Database configuration

In its default configuration, Petclinic uses an in-memory database (H2) which gets populated at startup with data. The h2 console is automatically exposed at http://localhost:8080/h2-console and it is possible to inspect the content of the database using the jdbc:h2:mem:testdb url.

A similar setup is provided for MySql in case a persistent database configuration is needed. Note that whenever the database type is changed, the app needs to be run with a different profile: spring.profiles.active=mysql for MySql.

You could start MySql locally with whatever installer works for your OS, or with docker:

docker run -e MYSQL_USER=petclinic -e MYSQL_PASSWORD=petclinic -e MYSQL_ROOT_PASSWORD=root -e MYSQL_DATABASE=petclinic -p 3306:3306 mysql:5.7.8

Further documentation is provided here.

Working with Petclinic in your IDE

Prerequisites

The following items should be installed in your system:

• Java 8 or newer.
• git command line tool (https://help.github.com/articles/set-up-git)
• Your preferred IDE
  • Eclipse with the m2e plugin. Note: when m2e is available, there is an m2 icon in Help -> About dialog. If m2e is not there, just follow the install process here: https://www.eclipse.org/m2e/
  • Spring Tools Suite (STS)
  • IntelliJ IDEA
  • VS Code

Steps:

1. On the command line

   git clone https://github.com/spring-projects/spring-petclinic.git
   

2. Inside Eclipse or STS

   File -> Import -> Maven -> Existing Maven project
   

   Then either build on the command line ./mvnw generate-resources or using the Eclipse launcher (right click on project and Run As -> Maven install) to generate the css. Run the application main method by right clicking on it and choosing Run As -> Java Application.

3. Inside IntelliJ IDEA In the main menu, choose File -> Open and select the Petclinic pom.xml. Click on the Open button.

   CSS files are generated from the Maven build. You can either build them on the command line ./mvnw generate-resources or right click on the spring-petclinic project then Maven -> Generates sources and Update Folders.

   A run configuration named PetClinicApplication should have been created for you if you're using a recent Ultimate version. Otherwise, run the application by right clicking on the PetClinicApplication main class and choosing Run 'PetClinicApplication'.

4. Navigate to Petclinic

   Visit http://localhost:8080 in your browser.

Looking for something in particular?

Spring Boot Configuration	Class or Java property files
The Main Class	PetClinicApplication
Properties Files	application.properties
Caching	CacheConfiguration

Interesting Spring Petclinic branches and forks

The Spring Petclinic "main" branch in the spring-projects GitHub org is the "canonical" implementation, currently based on Spring Boot and Thymeleaf. There are quite a few forks in a special GitHub org spring-petclinic. If you have a special interest in a different technology stack that could be used to implement the Pet Clinic then please join the community there.

Interaction with other open source projects

One of the best parts about working on the Spring Petclinic application is that we have the opportunity to work in direct contact with many Open Source projects. We found some bugs/suggested improvements on various topics such as Spring, Spring Data, Bean Validation and even Eclipse! In many cases, they've been fixed/implemented in just a few days. Here is a list of them:

Name	Issue
Spring JDBC: simplify usage of NamedParameterJdbcTemplate	SPR-10256 and SPR-10257
Bean Validation / Hibernate Validator: simplify Maven dependencies and backward compatibility	HV-790 and HV-792
Spring Data: provide more flexibility when working with JPQL queries	DATAJPA-292

Contributing

The issue tracker is the preferred channel for bug reports, features requests and submitting pull requests.

For pull requests, editor preferences are available in the editor config for easy use in common text editors. Read more and download plugins at https://editorconfig.org. If you have not previously done so, please fill out and submit the Contributor License Agreement.

License

The Spring PetClinic sample application is released under version 2.0 of the Apache License.

Deployment with skaffold

Build the application and deploy to Kubernetes

For a local cluster like Minikube or Docker Desktop you can simply run:

skaffold run --port-forward --profile=local --tail

For a remote cluster you need to specify the default-repo which is the registry prefix for the image that is being built. For Docker Hub the prefix would be your Docker ID, for other registries it would typically be the registry URL plus your project.

NOTE: You must specify a registry prefix where you have permission to push images.

You can do this globally by running:

skaffold config set --global default-repo ${REGISTRY_PREFIX}

Or, you can set it for the current Kubernetes context:

skaffold config set default-repo ${REGISTRY_PREFIX}

Finally, you can specify it as part of the run command:

skaffold run --default-repo ${REGISTRY_PREFIX} --port-forward --tail

The skaffold run command will build the container image, deploy the application and port-forward the service to localhost:8080

Open another terminal window to interract with the application or Kubernetes API server.

You can use kubectl get all to verify that the resources were created.

If you leave out the --port-forward option then accessing the application's endpoint varies based on the type of Kubernetes cluster and ingress configuration you are using.

Delete the application

To delete the deployment and the service from your Kubernetes cluster run:

skaffold delete