Spring PetClinic Sample Application

Preparing an IDE environment

Create a Cloud9 instance with m5.large or m5.xlarge.

Increase the size of disk volumes

pip3 install --user --upgrade boto3
export instance_id=$(curl -s http://169.254.169.254/latest/meta-data/instance-id)
python -c "import boto3
import os
from botocore.exceptions import ClientError 
ec2 = boto3.client('ec2')
volume_info = ec2.describe_volumes(
    Filters=[
        {
            'Name': 'attachment.instance-id',
            'Values': [
                os.getenv('instance_id')
            ]
        }
    ]
)
volume_id = volume_info['Volumes'][0]['VolumeId']
try:
    resize = ec2.modify_volume(    
            VolumeId=volume_id,    
            Size=30
    )
    print(resize)
except ClientError as e:
    if e.response['Error']['Code'] == 'InvalidParameterValue':
        print('ERROR MESSAGE: {}'.format(e))"
if [ $? -eq 0 ]; then
    sudo reboot
fi

Install brew package manager https://brew.sh/

sudo passwd ec2-user # Change the user password
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

Run these two commands in your terminal to add Homebrew to your PATH:

    echo 'eval "$(/home/linuxbrew/.linuxbrew/bin/brew shellenv)"' >> /home/ec2-user/.bash_profile
    eval "$(/home/linuxbrew/.linuxbrew/bin/brew shellenv)"

Install Maven

brew install maven

Get your account ID

TeamRole:~/environment/spring-petclinic (main) $ export ACCOUNT_ID=$(aws sts get-caller-identity --query 'Account' --output text)

Building a Container

There are many different ways to build a container image.

Create the container repo

TeamRole:~/environment/spring-petclinic (main) $ aws ecr create-repository --repository-name pet-clinic 
{
    "repository": {
        "repositoryUri": "537400238734.dkr.ecr.us-west-2.amazonaws.com/pet-clinic", 
        "imageScanningConfiguration": {
            "scanOnPush": false
        }, 
        "encryptionConfiguration": {
            "encryptionType": "AES256"
        }, 
        "registryId": "537400238734", 
        "imageTagMutability": "MUTABLE", 
        "repositoryArn": "arn:aws:ecr:us-west-2:537400238734:repository/pet-clinic", 
        "repositoryName": "pet-clinic", 
        "createdAt": 1652155776.0
    }
}

Build with a Dockerfile (a fat jar)

FROM openjdk:8-jre-alpine
VOLUME /tmp
ARG JAVA_OPTS
ENV JAVA_OPTS=$JAVA_OPTS
COPY target/spring-petclinic-2.6.0-SNAPSHOT.jar springpetclinic.jar
EXPOSE 3000
# ENTRYPOINT exec java $JAVA_OPTS -jar springpetclinic.jar
# For Spring-Boot project, use the entrypoint below to reduce Tomcat startup time.
ENTRYPOINT exec java $JAVA_OPTS -Djava.security.egd=file:/dev/./urandom -jar springpetclinic.jar

Build your Docker image using the following commands:\

docker build -t pet-clinic .
docker tag pet-clinic:latest $ACCOUNT_ID.dkr.ecr.us-west-2.amazonaws.com/pet-clinic:latest
docker push $ACCOUNT_ID.dkr.ecr.us-west-2.amazonaws.com/pet-clinic:latest

Run the container locally

docker run -p 8080:8080 pet-clinic

Use Jib Run commands for example

aws ecr get-login-password --region us-west-2 | docker login --username AWS --password-stdin $ACCOUNT_ID.dkr.ecr.us-west-2.amazonaws.com
mvn com.google.cloud.tools:jib-maven-plugin:build -Dimage=ACCOUNT_ID.dkr.ecr.us-west-2.amazonaws.com/pet-clinic:latest

Run with spring boot plugins

./mvnw spring-boot:build-image -DskipTests -Dspring-boot.build-image.imageName=$ACCOUNT_ID.dkr.ecr.us-west-2.amazonaws.com/pet-clinic

Check ECR Console

Create ECS Task Definition

Create ECS Service

View Metrics

Stress with hey

brew install hey

URL=http://my-load-balancer-831059280.us-west-2.elb.amazonaws.com
hey -c 200 -z 10m $URL

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 (it should work just as well with Java 11 or newer):

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

NOTE: Windows users should set git config core.autocrlf true to avoid format assertions failing the build (use --global to set that flag globally).

NOTE: If you prefer to use Gradle, you can build the app using ./gradlew build and look for the jar file in build/libs.

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 and PostgreSQL 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 or spring.profiles.active=postgres for PostgreSQL.

You could start MySQL or PostgreSQL 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

docker run -e POSTGRES_USER=petclinic -e POSTGRES_PASSWORD=petclinic -e POSTGRES_DB=petclinic -p 5432:5432 postgres:14.1

Further documentation is provided for MySQL and for PostgreSQL.

Compiling the CSS

There is a petclinic.css in src/main/resources/static/resources/css. It was generated from the petclinic.scss source, combined with the Bootstrap library. If you make changes to the scss, or upgrade Bootstrap, you will need to re-compile the CSS resources using the Maven profile "css", i.e. ./mvnw package -P css. There is no build profile for Gradle to compile the CSS.

Working with Petclinic in your IDE

Prerequisites

The following items should be installed in your system:

Java 11 or newer (full JDK not a JRE).
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:

On the command line

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

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.
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'.
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.

lindarr915 / spring-petclinic