Allow hosting from different base url / homepage

[MrHen]

Issue description

I need a way to prepend a specific url to both the root location and viewer.js. I am hosting the bundle viewer through a docker container and am running nginx to route various urls into the servers.

As best as I can tell, one of the the following changes would give me a way to do what I want:

• Change the link to viewer.js to prepend a base url setting: https://github.com/webpack-contrib/webpack-bundle-analyzer/blob/master/views/viewer.ejs#L8
• Expose the projectRoot option for configuration: https://github.com/webpack-contrib/webpack-bundle-analyzer/blob/master/src/viewer.js#L48

Technical info

• Webpack Bundle Analyzer version: webpack-bundle-analyzer@3.1.0
• Webpack version:

+-- react-scripts@2.1.8 
| `-- webpack@4.28.3 

• Node.js version: v8.15.0
• npm/yarn version: npm 6.4.1
• OS: Docker

Debug info

CLI command:
react-scripts build --stats && webpack-bundle-analyzer build/bundle-stats.json -m server -O --port 8888 --host 0.0.0.0

nginx configuration:

upstream analyzer {
    server reporting-2-analyzer:8888;
}

server {
    # ...
    location /analyzer {
        proxy_pass http://analyzer;
    }

    # webpack-bundle-analyzer does not support a base url
    location /viewer.js {
        proxy_pass http://analyzer;
    }

[th0r]

@MrHen will usage of the relative url for viewer.js help? E.g.

<script src="viewer.js"></script>

[MrHen]

@th0r Yeah, that would probably work.

[MrHen]

I confirmed the fix on my end. Thanks @th0r !