PowerSync + Node.js + Railway Backend

Overview

This repo contains a starter Node.js server application which has HTTP endpoints to authorize a PowerSync enabled application to sync data between a SQLite client and a Postgres database. This repo is intended for use as a starter template on Railway.

For an overview of PowerSync, see here.

Once you have deployed this template on Railway, you'll need to:

• Implement endpoints to accept client writes
• Implement an endpoint that generates a JWT for clients to use
• Implement a JWKS endpoint, used by PowerSync to authenticate JWTs

Accepting Client Writes

The relevant endpoints are:

1. PUT /api/data

   • PowerSync uses this endpoint to sync upsert events that occurred on the client application.

2. PATCH /api/data

   • PowerSync uses this endpoint to sync update events that occurred on the client application.

3. DELETE /api/data

   • PowerSync uses this endpoint to sync delete events that occurred on the client application.

Generating Client JWT

See our docs for additional details.

1. GET /api/auth/token
   • PowerSync uses this endpoint to retrieve an JWT token that is generated by the server and is used to authenticate requests.

JWKS endpoint

1. GET api/auth/keys
   • PowerSync uses this endpoint to retrieve the JWKS to validate the token provided in the response above.

Packages Used

• node-postgres is used to interact with the Postgres database when a PowerSync enabled client performs requests to the /api/data endpoint.
• jose is used to sign the JWT which PowerSync uses for authorization.

Setup

1. Clone the repository and nvm use && yarn install

2. Generate a new public/private key pair by running the following command:

yarn keys

This will output two new keys in the terminal window. Set these as environment variables on the Railway app:

POWERSYNC_JWT_PUBLICKEY
POWERSYNC_JWT_PRIVATEKEY

Local Development

1. Create a new .env file in the root project directory and add the variables as defined in the .env file:

cp .env.template .env

2. Run the following to start the application

yarn start

This will start the app on http://127.0.0.1:PORT, where PORT is what you specify in your .env file.

3. Test if the app is working by opening http://127.0.0.1:PORT/api/auth/keys/ in the browser

4. You should get a JSON object as the response to that request