Prerequisites

First install http-server and ngrok globally

npm i -g http-server ngrok

Usage

Run a local web server

http-server -p 8080

Create a publicly facing URI to connect to you local web server

ngrok http 8080

Browse to

https://<your sub domain>.ngrok.io/atlassian-connect.json

to make sure the app is running.

Open up the app in your editor and open your atlassian-connect.json file. Find the baseUrl property and change it to

https://<your sub domain>.ngrok.io

Navigate to the "Manage add-ons" section in Confluence.

Click the "Upload add-on" link and paste in the url to you atlassian-connect.json file

https://<your sub domain>.ngrok.io/atlassian-connect.json

Then hit "upload".