Arvados

All the install guides for Rails servers currently tell you to install the Rails package, then install nginx. This now generates confusing warnings, because the Rails server postinst scripts try to find the Web server they're running under, and may not find anything if you're really starting from scratch.

The best flow now is:

1. Install all the software we're going to install, except the Rails package itself. (This is a good chance of unify on the language from the SSO server about how when you're installing nginx, you only follow one page of instructions.)
2. Install the Rails package.
3. Edit the Rails package's configuration files.
4. (API only: set up the Puma runit service.)
5. Edit the nginx configuration to proxy the Rails server.
6. Reconfigure/reinstall the Rails package.

If you do that right, everything should be working at the end of the last step, and it requires a minimum of backtracking.