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Docs/Integrations/Deno

Use Neon with Deno Deploy

Connect a Neon Postgres database to your Deno Deploy application

Deno Deploy is a scalable serverless platform for running JavaScript, TypeScript, and WebAssembly at the edge, designed by the creators of Deno. It simplifies the deployment process and offers automatic scaling, zero-downtime deployments, and global distribution.

This guide demonstrates how to connect to a Neon Postgres database from a simple Deno application that uses deno-postgres driver to interact with the database.

The guide covers two deployment options:

Prerequisites

To follow the instructions in this guide, you will need:

  • A Neon project. If you do not have one, sign up at Neon. Your Neon project comes with a ready-to-use Postgres database named neondb. We'll use this database in the following examples.
  • To use the Deno Deploy serverless platform, you require a Deno Deploy account. Visit Deno Deploy to sign up or log in.

Retrieve your Neon database connection string

Retrieve your database connection string from the Connection Details widget in the Neon Console.

Your connection string should look something like this:

postgresql://alex:AbC123dEf@ep-cool-darkness-123456.us-east-2.aws.neon.tech/neondb?sslmode=require

You'll need the connection string a little later in the setup.

Deploy your application locally with Deno Runtime

Deno Runtime is an open-source runtime for TypeScript and JavaScript. The following instructions describe how to deploy an example application locally using Deno Runtime.

Install the Deno Runtime and deployctl

Follow the Install Deno and deployctl instructions in the Deno documentation to install the Deno runtime and deployctl command-line utility on your local machine.

Create the example application

Next, create the server.ts script on your local machine.

// server.ts

import * as postgres from 'https://deno.land/x/postgres@v0.17.0/mod.ts';

const databaseUrl = Deno.env.get('DATABASE_URL')!;

const pool = new postgres.Pool(databaseUrl, 3, true);

const connection = await pool.connect();
try {
  await connection.queryObject`
    CREATE TABLE IF NOT EXISTS books (
      id SERIAL PRIMARY KEY,
      title TEXT NOT NULL,
      author TEXT NOT NULL
    );
  `;

  // Check if the table is empty by getting the count of rows
  const result = await connection.queryObject<{ count: number }>`
    SELECT COUNT(*) AS count FROM books;
  `;
  const bookCount = Number(result.rows[0].count);

  if (bookCount === 0) {
    // The table is empty, insert the book records
    await connection.queryObject`
      INSERT INTO books (title, author) VALUES
        ('The Hobbit', 'J. R. R. Tolkien'),
        ('Harry Potter and the Philosopher''s Stone', 'J. K. Rowling'),
        ('The Little Prince', 'Antoine de Saint-Exupéry');
    `;
  }
} finally {
  connection.release();
}

Deno.serve(async (req) => {
  const url = new URL(req.url);
  if (url.pathname !== '/books') {
    return new Response('Not Found', { status: 404 });
  }

  const connection = await pool.connect();
  try {
    switch (req.method) {
      case 'GET': {
        const result = await connection.queryObject`SELECT * FROM books`;
        const body = JSON.stringify(result.rows, null, 2);
        return new Response(body, {
          headers: { 'content-type': 'application/json' },
        });
      }
      default:
        return new Response('Method Not Allowed', { status: 405 });
    }
  } catch (err) {
    console.error(err);
    return new Response(`Internal Server Error\n\n${err.message} `, {
      status: 500,
    });
  } finally {
    connection.release();
  }
});

The script creates a table named books in the neondb database if it does not exist and inserts some data into it. It then starts a server that listens for requests on the /books endpoint. When a request is received, the script returns data from the books table.

Run the script locally

To run the script locally, set the DATABASE_URL environment variable to the Neon connection string you copied earlier.

export DATABASE_URL=YOUR_NEON_CONNECTION_STRING

Then, run the command below to start the app server. The --allow-env flag allows the script to access the environment variables, and the --allow-net flag allows the script to make network requests. If the Deno runtime prompts you to allow these permissions, enter y to continue.

deno run --allow-env --allow-net server.ts

Query the endpoint

You can request the /books endpoint with a cURL command to view the data returned by the script:

curl http://localhost:8000/books

The cURL command should return the following data:

[
  {
    "id": 1,
    "title": "The Hobbit",
    "author": "J. R. R. Tolkien"
  },
  {
    "id": 2,
    "title": "Harry Potter and the Philosopher's Stone",
    "author": "J. K. Rowling"
  },
  {
    "id": 3,
    "title": "The Little Prince",
    "author": "Antoine de Saint-Exupéry"
  }
]%

Deploy your application with Deno Deploy

Deno Deploy is a globally distributed platform for serverless JavaScript applications. Your code runs on managed servers geographically close to your users, enabling low latency and faster response times. Deno Deploy applications run on light-weight V8 isolates powered by the Deno runtime.

Set up the project

  1. If you have not done so already, install the deployctl command-line utility, as described above.

  2. If you have not done so already, create the example server.ts application on your local machine, as described above.

  3. Register or log in to Deno and navigate to the Create a project page, where you can select a project template for your preferred framework, link a code repo, or create an empty project.

  4. The example application in this guide is a simple Deno script you've created locally, so let's select the Create an empty project option. Note the name of your Deno Deploy project. You will need it in a later step. Projects are given a generated Heroku-style name, which looks something like this: cloudy-otter-57.

  5. Click the Settings button and add a DATABASE_URL environment variable. Set the value to your Neon connection string and click Save.

  6. To authenticate deployctl from the terminal, you will need an access token for your Deno Deploy account. Navigate back to your Deno dashboard and create a new access token. Copy the token value and set the DENO_DEPLOY_TOKEN environment variable on your local machine by running this command from your terminal:

    export DENO_DEPLOY_TOKEN=YOUR_ACCESS_TOKEN

Deploy using deployctl

To deploy the application, navigate to the directory of your server.ts application, and run the following command:

deployctl deploy --project=YOUR_DENO_DEPLOY_PROJECT_NAME --prod server.ts

The --prod flag specifies that the application should be deployed to the production environment.

The deployctl command deploys the application to the Deno Deploy serverless platform. Once the deployment is complete, you'll see a message similar to the following:

$ deployctl deploy --project=cloudy-otter-57 --prod server.ts
✔ Deploying to project cloudy-otter-57.
  ℹ The project does not have a deployment yet. Automatically pushing initial deployment to production (use --prod for further updates).
✔ Entrypoint: /home/ubuntu/neon-deno/server.ts
ℹ Uploading all files from the current dir (/home/ubuntu/neon-deno)
✔ Found 1 asset.
✔ Uploaded 1 new asset.
✔ Production deployment complete.
✔ Created config file 'deno.json'.

View at:
 - https://cloudy-otter-57-8csne31fymac.deno.dev
 - https://cloudy-otter-57.deno.dev

Verifying the deployment

You can now access the application at the URL specified in the output. You can verify its connection to your Neon database by visiting the /books endpoint in your browser or using cURL to see if the data is returned as expected.

$ curl https://cloudy-otter-57.deno.dev/books
[
  {
    "id": 1,
    "title": "The Hobbit",
    "author": "J. R. R. Tolkien"
  },
  {
    "id": 2,
    "title": "Harry Potter and the Philosopher's Stone",
    "author": "J. K. Rowling"
  },
  {
    "id": 3,
    "title": "The Little Prince",
    "author": "Antoine de Saint-Exupéry"
  }
]

To check the health of the deployment or modify settings, navigate to the Project Overview page and select your project from the Projects list.

Deploying using Github

When deploying a more complex Deno application, with custom build steps, you can use Deno's Github integration. The integration lets you link a Deno Deploy project to a GitHub repository. For more information, see Deploying with GitHub.

Removing the example application and Neon project

To delete the example application on Deno Deploy, follow these steps:

  1. From the Deno Deploy dashboard, select your Project.
  2. Select the Settings tab.
  3. In the Danger Zone section, click Delete and follow the instructions.

To delete your Neon project, refer to Delete a project.

Source code

You can find the source code for the application described in this guide on GitHub.

Resources

Need help?

Join our Discord Server to ask questions or see what others are doing with Neon. Users on paid plans can open a support ticket from the console. For more detail, see Getting Support.

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