Edit Dockerfile to use multi stage build and nginx

[vemonet]

I faced issues trying to run the current Dockerfile:

• The entrypoint npm start deploys on 8080, but port 3000 is exposed in Dockerfile and documentation
• I could not access the application when running with docker run (I tried with port 3000 and 8080, but none of them were working)

So I wrote a 2 stages build:

• First stage uses node to compile website for production (using already existing script npm run production)
• Second stage uses nginx to deploy the precompiled website (cleaner container with only the necessary files)

Settings and queries can still be passed at runtime by sharing the queries.json file as volume to /usr/share/nginx/html/queries.json inside the container!

docker run -v $(pwd)/queries.json:/usr/share/nginx/html/queries.json -p 3000:80 -it --rm comunica-sparql-widget

Instructions for Docker have been added to the README

Thanks a lot for this cool widget!

[rubensworks]

Ah, I wasn't aware the Dockerfile was in fact broken. Thanks a lot for this!