---
title: "Connect to Postgres"
---

:::info Legacy Documentation

You are viewing legacy documentation for Deno Deploy Classic. We recommend
migrating to the new
<a href="/deploy/">Deno Deploy</a> platform.

:::

This tutorial covers how to connect to a Postgres database from an application
deployed on Deno Deploy.

## Setup Postgres

> This tutorial will focus entirely on connecting to Postgres unencrypted. If
> you would like to use encryption with a custom CA certificate, use the
> documentation [here](https://deno-postgres.com/#/?id=ssltls-connection).

To get started, we need to create a new Postgres instance for us to connect to.
For this tutorial, we will be using [Supabase](https://supabase.com) as they
provide free, managed Postgres instances. If you like to host your database
somewhere else, you can do that too.

1. Visit https://app.supabase.io/ and click **New project**.
2. Select a name, password, and region for your database. Make sure to save the
   password, as you will need it later.
3. Click **Create new project**. Creating the project can take a while, so be
   patient.

## Gather credentials from Postgres

Once you've set up your Postgres database, gather your connection information
from your Postgres instance.

### Supabase

For the Supabase instance above, to get your connection information:

1. Navigate to the **Database** tab on the left.
2. Go to the **Project Settings** >> **Database** and copy the connection string
   from the **Connection String** >> **URI** field. This is the connection
   string you will use to connect to your database. Insert the password you
   saved earlier into this string, and then save the string somewhere - you will
   need it later.

### psql

If you are using psql, you should generally be able to find your connection
information by running:

```psql
test=# \conninfo
```

Your Postgres connection string will take the form:

```sh
postgres://user:password@127.0.0.1:5432/deploy?sslmode=disable
```

## Create a project in Deno Deploy

Next, let's create a project in Deno Deploy Classic and set it up with the
requisite environment variables:

1. Go to [https://dash.deno.com/new](https://dash.deno.com/new) (Sign in with
   GitHub if you didn't already) and click on **+ Empty Project** under **Deploy
   from the command line**.
2. Now click on the **Settings** button available on the project page.
3. Navigate to **Environment Variables** Section and add the following secrets.

- `DATABASE_URL` - The value should be your connection string that you retrieved
  in the last step.

![postgres_env_variable](../docs-images/postgres_env_variable.png)

## Write code that connects to Postgres

To read/write to Postgres, import a suitable Postgres module such as
[this one from JSR](https://jsr.io/@bartlomieju/postgres), read the connection
string from the environment variables, and create a connection pool.

```ts
import { Pool } from "jsr:@bartlomieju/postgres";

// Get the connection string from the environment variable "DATABASE_URL"
const databaseUrl = Deno.env.get("DATABASE_URL")!;

// Create a database pool with three connections that are lazily established
const pool = new Pool(databaseUrl, 3, true);

// Connect to the database
const connection = await pool.connect();

try {
  // Create the table
  await connection.queryObject`
    CREATE TABLE IF NOT EXISTS todos (
      id SERIAL PRIMARY KEY,
      title TEXT NOT NULL
    )
  `;
} finally {
  // Release the connection back into the pool
  connection.release();
}
```

## Deploy application to Deno Deploy Classic

Once you have finished writing your application, you can deploy it on Deno
Deploy Classic.

To do this, go back to your project page at
`https://dash.deno.com/projects/<project-name>`.

You should see a couple of options to deploy:

- [Github integration](ci_github)
- [`deployctl`](./deployctl.md)
  ```sh
  deployctl deploy --project=<project-name> <application-file-name>
  ```

Unless you want to add a build step, we recommend that you select the Github
integration.

For more details on the different ways to deploy on Deno Deploy Classic and the
different configuration options, read [here](how-to-deploy).