Windows publish to generic provider

I want to include the ability to publish (as I've done through electron-builder before) a Windows app to a S3 bucket, in order to be able to use electron-builder's auto-upload.

I'm on the stage of being able to deploy my packed app to the storage.

I have a .sh script to start the deployment:

```
cordova platform add electron

echo "Setting main.js ..."
cp res/electron/cdv-electron-main.js platforms/cordova-electron/platform_www/cdv-electron-main.js 2>/dev/null
cp res/electron/cdv-electron-main.js platforms/electron/platform_www/cdv-electron-main.js 2>/dev/null

echo "Package build ..."
webpack --config webpack.config.electron.production.js && cordova build electron --release --publish=always
echo "Done."
```

I also have a build.json file.

```
{
"electron": {
"linux": {
"package": [
"dir"
]
},
"windows": {
"publish": [
{
"provider": "s3",
"bucket": "hub-staticfiles.bexfyinfra.com"
}
],
"package": [
"portable"
]
}
}
}
```

and a bucket with the following permissions:
[![enter image description here][1]][1]

But I don't seem able to publish my app, get the latest.yml or anything of the sort. I believe I have the correct credentials in my .aws/credentials folder too.

Any ideas how can I go about making it work?

Thank you in advance.

[1]: https://i.stack.imgur.com/yON3z.png

Start with the deployment shell script and build.json, especially the electron windows publish configuration and the cordova build electron --release --publish=always command. Check how the packaged Windows app is passed to electron-builder and how the S3 credentials are read. Done means the app is uploaded to the bucket with the expected latest.yml generated.

Written by the indexing model from the issue text.