feature-toggle-express-middleware

This middleware manages feature toggles. You can switch on/off features using a query parameter. It stores them in a cookie.

const featureToggle = require('feature-toggle-express-middleware');

// pass a list of allowed features and a prefix representing your application
const featureToggleMiddleware = featureToggle(['feature1', 'feature2'], 'myapp');

app.get('/myapp', featureToggleMiddleware, (req, res) => {
  if (res.locals.hasToggle('feature1')) {
    res.send('Feature 1 active');
  }
  res.send('Feature 1 not active');
});

featureToggle takes this arguments:

• an array with allowed toggles (a toggle is a string)
• a prefix that is used for the cookie and the query parameters
• [optional] the options for the cookie (see expressjs documentation)
• [optional] a boolean that when true, disable automatic cache control headers

Using the middleware

You can switch a feature on using the addToggles query parameter:

http://www.example.com?myappAddToggles=feature1

You can also enable multiple features:

http://www.example.com?myappAddToggles=feature1,feature2

You can remove one or more feature:

http://www.example.com?myappRemoveToggles=feature1
http://www.example.com?myappRemoveToggles=feature1,feature2

You can use both query parameter to add/remove toggles

http://www.example.com?myappRemoveToggles=feature1&myappAddToggles=feature2

You can switch off all toggles:

http://www.example.com?myappResetToggles=true

allow-feature

This is another middleware that, used together with featureToggle enable/disable a specific endpoint.

const allowFeature = require('feature-toggle-express-middleware/allow-feature');

const disableWithFeature1 = allowFeature.allowWith('feature1');
const enableWithFeature1 = allowFeature.disallowWith('feature1');

app.get('/myapp/1', featureToggleMiddleware, disableWithFeature1, (req, res) => {
  console.log('this is disabled with feature1');
});

app.get('/myapp/2', featureToggleMiddleware, enableWithFeature1, (req, res) => {
  console.log('this is enabled with feature1');
});

Notes

This module is implemented with ES6 feature. Use it with the appropriate node versions. The middleware provides to disable cache (using cache headers), when a feature toggle is enabled.