Judoscale for Express.js

Official Judoscale adapter package for Express.js applications.

Set up your Express app for autoscaling

1. Install the judoscale-express package:

npm install judoscale-express --save

2. Import and use the provided middleware:

Judoscale should be one of the first middlewares for your app.

// ES6-style import:
import judoscale from 'judoscale-express'

// Or if you use `require` for importing:
const judoscale = require('judoscale-express').default

// default configuration
app.use(judoscale())

// custom configuration (see config options below)
app.use(
  judoscale({
    log_level: 'debug',
  })
)

Configuration

Most Judoscale settings are handled via the Judoscale dashboard, but there are a few ways you can configure the adapter in code:

app.use(
  judoscale({
    // Use a custom logger instance
    // Default: Winston logger instance (simple format)
    logger: myLogger,

    // Override the log level of the default logger (ignored if logger is overridden)
    // Default: process.env.JUDOSCALE_LOG_LEVEL || 'info'
    log_level: 'debug',
  })
)

Troubleshooting

Once installed, you should see something like this in your development log:

[Judoscale] Reporter not started: JUDOSCALE_URL is not set

In production, run heroku logs -t | grep Judoscale, and you should see something like this:

[Judoscale] Reporter starting, will report every 10 seconds

If you don't see either of these, ensure "judoscale-express" is in your Package.lock file, and restart your app.

You can see more detailed (debug) logging by setting JUDOSCALE_LOG_LEVEL on your Heroku app:

heroku config:set JUDOSCALE_LOG_LEVEL=debug

Reach out to [email protected] if you run into any other problems.