Connecting to Postgres with a static IP from a Node app on Fly.io

Recommended setup

Use Fixie Socks proxy for Postgres connections to a database that only accepts traffic from approved IP addresses. Store the proxy value in FIXIE_SOCKS_HOST, then configure Node.js to route outbound traffic through Fixie before connecting to Postgres.

Set up Fixie on Fly.io

Create a Fixie Socks proxy in the Fixie dashboard. Copy the proxy value into Fly.io secrets as FIXIE_SOCKS_HOST, and copy the outbound IPs into the destination allowlist.

Set a Fly.io secret

fly secrets set FIXIE_SOCKS_HOST=...

Implementation

The example below shows the core application-side change. Keep credentials in environment variables and avoid committing proxy, database, or API secrets.

Connect to Postgres through FIXIE_SOCKS_HOST

const pg = require('pg');
const SocksConnection = require('socksjs');

const fixieValues = process.env.FIXIE_SOCKS_HOST.split(new RegExp('[/(:\\/@)/]+'));

const databaseServer = {
  host: 'postgres.example.com',
  port: 5432,
};

const fixieConnection = new SocksConnection(databaseServer, {
  user: fixieValues[0],
  pass: fixieValues[1],
  host: fixieValues[2],
  port: fixieValues[3],
});

const client = new pg.Client({
  user: process.env.DB_USER,
  password: process.env.DB_PASSWORD,
  database: process.env.DB_NAME,
  stream: fixieConnection,
  ssl: true,
});

client.connect()
  .then(() => client.query('select 1 as ok'))
  .then((result) => console.log(result.rows[0]));

Good to know

• This is for external databases; Fly Postgres reached over the internal private network needs no proxy at all.
• Set FIXIE_SOCKS_HOST with fly secrets set so it is encrypted at rest and injected at boot.
• Match the Fixie region to your primary machine region — database round-trips amplify added latency far more than one-off API calls.

Allowlist and test the static IPs

1. Open the Fixie dashboard and copy the outbound IP addresses for this proxy.
2. Add both IPs to the Postgres firewall or security group.
3. Deploy the updated Node.js app on Fly.io.
4. Run a small connection test before sending production traffic.

Related guides

• Making API requests with a static IP from a Node app on Fly.io
• Connecting to Postgres with a static IP from a Node app on Heroku
• Connecting to Postgres with a static IP from a Node app on Vercel
• Connecting to Postgres with a static IP from a Node app on Render
• Connecting to Postgres with a static IP from a Node app on AWS Lambda

Related docs

• Node.js implementation examples
• Fly.io setup documentation
• Postgres connection guide
• Fixie-Wrench for TCP forwarding