Proposal: JavaScript API for the ability to run mocker on existing server endpoint

[SuperOleg39]

Motivation

Current JS / CLI mountebank API immediately create and start new http server.
It means, if we want to test one NodeJS micro-service, we need to create and deploy two containers - one with our service, and one with mountebank.
If we have a k8s infrastructure, many applications, and dynamic deployed stands with automated testing, just one additional container with mountebank for every application complicates deployment and take many k8s resources.

But what if we can create mountebank instance on existing NodeJS application, at new endpoint?

Our micro-service can on demand run integration with mountebank, where we create new express endpoint, /mountebank for example, and pass req and res objects to special mountebank JS API.
After, this micro-service can replace http requests base URL to mocked API to http://localhost:3000/mountebank.

For SSR NodeJS applications, on client-side, will be available a relative URL /mountebank (nuances with a gateway proxy are possible).

API overview

Few examples, how new API may looks like

Nested express.js routers

Inspired by this reciepe

const express = require('express')
const { createRouter } = require('mountebank')

const app = express();

const mountebankRouter = await createRouter(options)

app.use('/mountebank/*', mountebankRouter)

express.js middeware

const express = require('express')
const { createMiddleware } = require('mountebank')

const app = express();

const mountebankMiddleware = await createMiddleware(options)

app.use('/mountebank/*', mountebankMiddleware)

express.js application

Example for clean http NodeJS server

const http = require('http')
const { createApp } = require('mountebank')

const mountebankApp = await createApp(options)

const server = createServer((req, res) => {
  if (req.url.startsWith('/mountebank')) {
    mountebankApp(req, res);
  }
});

server.listen(port);

Implementation

If this feature is discussible, and don't break some mountebank core concepts, i can start from a simple demo branch, for this proposal.

[dzotovwork]

Awesome proposal !!!! 👍

[vchuchkalov]

Hi @bbyars. What do you say?

[bbyars]

I'm comfortable with the suggestion. It's close to being possible now (look at the commented out lines starting at line 39 <https://github.com/bbyars/mountebank/blob/master/mbTest/perf/databaseConcurrencyTest.js>). It might involve moving some CLI option defaults from the current cli.js into mountebank.js to avoid having to pass defaults that mountebank expects (as shown in the link), adding an option to adjust the root path, and avoiding the socket bind, but looks reasonably straightforward.

…

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[SuperOleg39]

Thank you for the recommendations!

Will start working on this soon)

[SuperOleg39]

@bbyars , hi!

Create PR, but not sure about all changes:

• defaults implementation seems to be unfortunate
• listenServer method may be unnecessary

Will waiting review)

[SuperOleg39]

Need to create some publicPath option for static assets and links on mountebank web interface, because current relative path always see to current domain.
I think, will be better to create another PR)