Ocean Data Viewer is a pretty standard Rails application, backed by a Postgres database, with the paperclip gem to manage attachments. To run Ocean Data Viewer, make sure to have ImageMagick installed, and then proceed with the usual commands:
$ git clone https://github.com/unepwcmc/ocean-data-viewer.git ocean-data-viewer
$ cd ocean-data-viewer
$ bundle install
$ bundle exec rake db:setup
Ocean Data Viewer uses the dotenv gem to manage environment variables. Before starting the server, create a copy of the file .env.example (removing the .example bit) and edit the needed variables. After this final step, bundle exec rails server should work like a charm.
Note: this applies to all environments, so make sure to have a .env file in your capistrano linked_files when deploying.