Quarkus demo: Hibernate Reactive and RESTEasy Reactive

This is a minimal CRUD service exposing a couple of endpoints over REST, with a front-end based on Angular so you can play with it from your browser.

While the code is surprisingly simple, under the hood this is using:

RESTEasy Reactive to expose the REST endpoints
Hibernate Reactive to perform the CRUD operations on the database
A PostgreSQL database; see below to run one via Docker
ArC, the CDI inspired dependency injection tool with zero overhead

Requirements

To compile and run this demo you will need:

JDK 17+
GraalVM

In addition, you will need either a PostgreSQL database, or Docker to run one.

Configuring GraalVM and JDK 17+

Make sure that both the GRAALVM_HOME and JAVA_HOME environment variables have been set, and that a JDK 17+ java command is on the path.

See the Building a Native Executable guide for help setting up your environment.

Building the demo

Launch the Maven build on the checked out sources of this demo:

./mvnw package

Running the demo

Live coding with Quarkus

The Maven Quarkus plugin provides a development mode that supports live coding. To try this out:

./mvnw quarkus:dev

In this mode you can make changes to the code and have the changes immediately applied, by just refreshing your browser.

Dev Mode automatically starts a Docker container with a Postgres database. This feature is called "Dev Services."

To access the database from the terminal, run:

docker exec -it <container-name> psql -U quarkus

Hot reload works even when modifying your JPA entities.
Try it! Even the database schema will be updated on the fly.

Run Quarkus in JVM mode

When you're done iterating in developer mode, you can run the application as a conventional jar file.

First compile it:

./mvnw package

Next, make sure you have a PostgreSQL database running. In production, Quarkus does not start a container for you like it does in Dev Mode. To set up a PostgreSQL database with Docker:

docker run -it --rm=true --name quarkus_test -e POSTGRES_USER=quarkus_test -e POSTGRES_PASSWORD=quarkus_test -e POSTGRES_DB=quarkus_test -p 5432:5432 postgres:13.3

Connection properties for the Agroal datasource are defined in the standard Quarkus configuration file, src/main/resources/application.properties.

Then run it:

java -jar ./target/quarkus-app/quarkus-run.jar

Have a look at how fast it boots.
Or measure total native memory consumption...

Run Quarkus as a native application

You can also create a native executable from this application without making any source code changes. A native executable removes the dependency on the JVM: everything needed to run the application on the target platform is included in the executable, allowing the application to run with minimal resource overhead.

Compiling a native executable takes a bit longer, as GraalVM performs additional steps to remove unnecessary codepaths. Use the native profile to compile a native executable:

./mvnw package -Dnative

After getting a cup of coffee, you'll be able to run this binary directly:

./target/hibernate-reactive-quickstart-1.0.0-SNAPSHOT-runner

Please brace yourself: don't choke on that fresh cup of coffee you just got.

Now observe the time it took to boot, and remember: that time was mostly spent to generate the tables in your database and import the initial data.

Next, maybe you're ready to measure how much memory this service is consuming.

N.B. This implies all dependencies have been compiled to native; that's a whole lot of stuff: from the bytecode enhancements that Hibernate ORM applies to your entities, to the lower level essential components such as the PostgreSQL JDBC driver, the Undertow webserver.

See the demo in your browser

Navigate to:

http://localhost:8080/index.html

Have fun, and join the team of contributors!

Running the demo in Kubernetes

This section provides extra information for running both the database and the demo on Kubernetes. As well as running the DB on Kubernetes, a service needs to be exposed for the demo to connect to the DB.

Then, rebuild demo docker image with a system property that points to the DB.

-Dquarkus.datasource.reactive.url=jdbc:postgresql://<DB_SERVICE_NAME>/quarkus_test