Toguru Client for Node.js

A TypeScript client for integrating Toguru into a Node.js environment

• Installation
• Usage
  • Base Client
  • Express Bridge
• Testing
  • Express

Installation

You can install the library with your package manager of choice

$ yarn add toguru-client
# or
$ npm install toguru-client

The client is fully written in TypeScript and comes with types out of the box.

Usage

Base Client

The library provides a base Toguru client that is independent of the framework or environment used, and can be used for AWS lambdas, Kafka streams, generic scripts, etc where toggling functionality might be needed. It allows computing toggle activations based on an activation context. For web application contexts, we recommend using the more specialized Express bridge, see below.

import { toguruClient, TogglingApiByActivationContext } from '@autoscout24/toguru-client'

const client: TogglingApiByActivationContext = toguruClient({
    endpoint: 'https://example.com/togglestate',
    refreshIntervalMs: 60 * 1000, // 1 minute
})

Once we have instantiated the client, it will poll the Toguru backend automatically and fetch all toggle information. The client needs an ActivationContext (user identifier, possible forced toggles, etc) which we can provide

const activationContext: ActivationContext = {
    uuid: 'ad89f957-d646-1111-1111-a02c9aa7faba',
    forcedToggles: {
        fooToggle: true,
    },
}

We can then use this context to finally compute toggle activations

client(activationContext).isToggleEnabled({ id: 'test-toggle', default: false }) // based on toguru data, fallback to `false`
client(activationContext).isToggleEnabled({ id: 'fooToggle', default: false }) // `true`
client(activationContext).togglesForService('service') // `Toggles` based on toguru data

Express Bridge

When working with a web application, it makes sense to compute toggle information based on the client's Request. The library provides an Express bridge that takes a base client and uses it to compute toggle activations based on a Request

Request-based client

We can create a client that will compute the activation context based on a Request.

import { client, toguruExpressBridge } from '@autoscout24/toguru-client'


const client = client({...}) // instantiate the base toguru client

const toguruExpressClient = toguruExpressBridge.client({
    client,
    extractors: {
        uuid: toguruExpressBridge.requestExtractors.cookieValue('user-id') // will attempt to pull the user uuid from the `user-id` cookie
    }
})

The extractors key allows customizing the behaviour, and will use certain defaults if not specified. When they are not specified, they will use defaults. After the express client is instantiated, it can be used to determine toggle activations

app.get('/some-route', (req, res) => {
      const testToggleIsOn = client(req).isToggleEnabled({ id: 'test-toggle', default: false })
      // ...
    }
))

Middleware

The library also provides an Express middleware that will augment then Request object with an additional toguru attribute. The instantiation options are the same as the express client above, and can be as follows

const toguruClientMiddleware = toguruExpressBridge.middleware(...) // same as `toguruExpressBridge.client`
app.get('/some-route', toguruClientMiddleware, (req, res) => {
      const testToggleIsOn = req.toguru.isToggleEnabled({ id: 'test-toggle', default: false })
      // ...
    }
))

Testing

In general, we recommend parametrizing your main application to take a toguru client interface, and instantiating the client itself at the very edge of your application (typically index.ts). This allows you to use different clients during tests that you can fully control without the need to introduce any mocking tools.

Express

Following the pattern align above, a typical Express application will look like

const application = (
    toguruMiddleware: Express.RequestHandler
) => {
  const app = express()
  app.get('/toguru-test', toguruMiddleware,...)
})

During tests, we can pass the express.stubToguruMiddleware or express.stubClient, depending on what the app is using, that easily allows you to instantiate the middleware/client with a given set of toggles, falling back to the toggle defaults for the rest.

stubToguruMiddleware([{ id: 'some-toggle', enabled: false }])