Our company is using Ubuntu as our main OS now. Before we decided to switch to 16.04 (with systemd) we used keyscript= crypttab option to manage some of our encrypted volumes.
Now with Systemd that's no longer possible and we're forced to use upstart, which in itself contains several nasty bugs at this time (these aren't exactly the scope of this bug though).
Due to removed functionality that was present in previous release, I still consider this a bug in cryptsetup even though it's related to upstream. I know that systemd introduced a concept of 'password agents' but AFAIK there's no way to automate the process of getting block device keys - because these agents only accept ASCII text (and our keys are already binary, that'd take a huge effort to redo everything to use, say, base64 anyway).
wrong package chosen