const app = new Koa()

app.use(async (ctx, next) => {
    await new Promise((resolve, reject) => {
        // `history` is memoryHistory, `store` is redux store, `routes` is usual react-router routes
        match({ history, routes, location: ctx.request.url }, (error, redirectLocation, renderProps) => {
            if (renderProps) {
                ctx.body = htmlTemplate(renderHTML(store, renderProps), store.getState()) // see below
                resolve()
            }
        })
    })
    await next()
})

app.listen(3000)