Hmm this PR seems fine but I'd like to make the upgrade UX clearer.

Can we rename any index.html/index.json files in the root dir to put their creation dates in the name?

data/
    index.html      ->        2020-08-08_index_old.html
    index.json      ->        2020-08-09_index_old.json
    index.sqlite3
    ArchiveBox.conf
    ...

That should make it clear that users need to manually export somehow in order to update those files.
It will also ensure that any tools relying on those files existing in the old location break, forcing people to update those tools to match the new behavior and export process requirements.

@pirate I renamed the indexes if they are present. Anything else missing?

I liked the index.html (although slow generation is clearly bad). Do you think you could add it as an option? A use case (an actual one) is statically hosting the archive directory. This won't work without extra work (basically gathering all files under archive/*/index.html and cobbling together an index.html)

@kedorlaomer you can still generate it using the list command. Something like archivebox list --html --index > index.html should work. We enabled that option, and disabled automatic generation.