Connecting with Node.js

This guide walks you through the process of connecting a Node.js application to a Hydra database using the pg package. You’ll learn how to set up the environment, configure the connection, and run a simple SQL query.

Variables

To connect to a Hydra database, the following parameters are required. You can find these details in the Elestio service overview page of your Hydra service.

These values can usually be found in the Elestio service overview details as shown in the image below, make sure to take a copy of these details and add it to the code moving ahead.

Prerequisites

• Install Node.js and NPM
  • Check if Node.js is installed:

node -v
npm -v

• • If not, download and install it from https://nodejs.org.
• Install the pg Package
  • Hydra is PostgreSQL-compatible, so use the pg package:

npm install pg --save

Code

Once all prerequisites are set up, create a new file named hydra.js and add the following code.

const { Client } = require("pg");

// Database connection configuration
const config = {
  host: "HOST",
  user: "USER",
  password: "PASSWORD",
  database: "DATABASE",
  port: PORT,
  ssl: {
    rejectUnauthorized: false, // Only if Hydra requires SSL (check Elestio settings)
  },
};

// Create a new client instance
const client = new Client(config);

// Connect to the Hydra database
client.connect((err) => {
  if (err) {
    console.error("Connection failed:", err.stack);
    return;
  }

  console.log("Connected to Hydra");

  // Run a test query
  client.query("SELECT version()", (err, res) => {
    if (err) {
      console.error("Query failed:", err.stack);
    } else {
      console.log("Hydra/PostgreSQL Version:", res.rows[0].version);
    }

    // Close the connection
    client.end((err) => {
      if (err) console.error("Error closing connection:", err.stack);
    });
  });
});

To execute the script, open the terminal or command prompt and navigate to the directory where hydra.js. Once in the correct directory, run the script with the command

node hydra.js

If successful, you’ll see:

Connected to Hydra
Hydra/PostgreSQL Version: PostgreSQL 14.13 (Debian 14.13-1.pgdg120+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 12.2.0-14) 12.2.0, 64-bit