Connect Quarkus (Reactive) to Neon

Quarkus is a Java framework optimized for cloud environments. This guide shows how to connect to Neon from a Quarkus project using a Reactive SQL Client.

To connect to Neon from a Quarkus application:

1. Create a Neon Project
2. Create a Quarkus project and add dependencies
3. Configure a PostgreSQL data source
4. Use the Reactive PostgreSQL client
5. Run the application

Create a Neon project

If you do not have one already, create a Neon project.

1. Navigate to the Projects page in the Neon Console.
2. Click New Project.
3. Specify your project settings and click Create Project.

Create a Quarkus project

Create a Quarkus project using the Quarkus CLI:

quarkus create app neon-with-quarkus \
--name neon-with-quarkus \
--package-name com.neon.tech \
--extensions reactive-pg-client,resteasy-reactive

You now have a Quarkus project in a folder named neon-with-quarkus with the Reactive Postgres client and RESTEasy Reactive extensions installed.

Configure a PostgreSQL data source

Create a .env file in the root of your Quarkus project directory. Configure a reactive data source using your Neon database connection string and specifying the database kind as shown:

# Note that "?sslmode=require" is appended to the Neon connection string
QUARKUS_DATASOURCE_REACTIVE_URL=postgres://[user]:[password]@[neon_hostname]/[dbname]?sslmode=require

Use the Reactive PostgreSQL client

Create a PostgresResource.java file in the same directory as the GreetingResource.java that was generated by Quarkus during project creation. Paste the following content into the PostgresResource.java file:

package com.neon.tech;

import jakarta.inject.Inject;
import io.smallrye.mutiny.Multi;
import io.vertx.mutiny.sqlclient.Row;
import io.vertx.mutiny.sqlclient.RowSet;
import jakarta.ws.rs.GET;
import jakarta.ws.rs.Path;
import jakarta.ws.rs.Produces;
import jakarta.ws.rs.core.MediaType;

@Path("/postgres")
public class PostgresResource {
    @Inject
    io.vertx.mutiny.pgclient.PgPool client;

    @GET
    @Path("/version")
    @Produces(MediaType.TEXT_PLAIN)
    public Multi<String> getVersion() {
        return client.query("SELECT version()")
                .execute()
                .onItem().transformToMulti(this::extractVersion);
    }

    private Multi<String> extractVersion(RowSet<Row> rowSet) {
        return Multi.createFrom().iterable(rowSet)
                .map(r -> r.getValue(0).toString());
    }
}

This code defines a HTTP endpoint that will query the database version and return it as a response to incoming requests.

Run the application

Start the application in development mode using the Quarkus CLI from the root of the project directory:

quarkus dev

Visit localhost:8080/postgres/version in your web browser. Your Neon database's Postgres version will be returned. For example:

PostgreSQL 15.4 on x86_64-pc-linux-gnu, compiled by gcc (Debian 10.2.1-6) 10.2.1 20210110, 64-bit