Found first hiccup: LiveJournal cross-post plugin did not work on the new site. The error was somewhat misleading: something like ‘message from www.livejournal.com: malformed, unable to parse’. In fact it was the local PHP code that was unable to parse the response from LiveJournal because of missing PHP XML plugin, but it took some debugging to detect.
I also found that I don’t have a nice process for updating dependencies like that (yet): have to pull/push and rebuild docker containers by hand: not cool. Will think on how to automate this.
Generally, whenever you remotely login into production machine to “customize” it, you open yourself to human error, and lose ability to reliably duplicate production environment at will: it is impossible to guarantee that whatever commands were run on current production would be repeated on the new one.