Arvados

• Migration loses data. If anything goes wrong, we can't just deploy an old version; everything is screwed until we fix all the bugs (or hastily write a real down-migration). Either
  • Make the down-migration restore the contents of the fields to what they were before, instead of leaving them null, or
  • Leave the database fields there (but don't use them in API responses) until we have deployed and we're confident everything works.
• "Combine selected collections" → "Can't mass-assign protected attributes: tail_kind, head_kind". grep -r reveals a bunch of *_kind stuff in apps/workbench and crunch_scripts/pgp-survey-import. (Should merge master, then try grep; new stuff in 2187.)
• We should (at least) ignore provided *_kind in create/update, and (as a convenience to the client) generate *_kind in API responses. Then our (and our poor users', if any) clients won't suddenly start failing.
  • Crashing when receiving *_kind makes jobs unrepeatable if people used *_kind like we told them to in their scripts (or just ran our example script).

As an aside, perhaps we should consider a deprecation approach -- e.g., include warnings in API responses, and make SDKs print them on stderr?