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

   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.

2. 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.

3. 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&channel_binding=require" is appended to the Neon connection string
   QUARKUS_DATASOURCE_REACTIVE_URL=postgresql://[user]:[password]@[neon_hostname]/[dbname]?sslmode=require&channel_binding=require

   note

   You can find the connection details for your database by clicking the Connect button on your Project Dashboard. For more information, see Connect from any application.

4. 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.

5. 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