Webpack middleware with Jekyll setup for context p

Question

I have a site hosted on github pages using Jekyll.

Essentially all I want to get Webpack server to load up :

http://localhost:8080/project/ - with the added feature being /project/ to make all my urls continue to work locally.

More on Jekyll setup:

To get all the url's working on github pages you have to set the base url: baseurl: "/project/" then when you reference a url you use:

<a href="{{ "page-1/" | prepend: site.baseurl }}">

which would output to

<a href="/project/page-1/">

I want to replicate this url structure with webpack middleware.

Firstly I set the webpack dev server to look at the built Jekyll site:

devServer: {
    contentBase: '_site/', //disk location
    watchContentBase: true
},

Then to make sure the files are served from /project/ I have added:

output: {
    filename: 'js/app.js',
    path: path.resolve(__dirname, ''),
},

I don't have Webpack building any html with HtmlWebpackPlugin, as that's what Jekyll is doing, so HTML webpack is not an option. Maybe some kind of express static server?

I have tried this but it doesn't seem to do anything :(

const express = require('express');
setup(app){
    app.use('_site/', express.static('/project/'));
}

Thanks.