It would be a lot simpler to do "transactional updates" by using Git FS like Webconverger does to roll out updates.
That way clients can see the exact changes at https://github.com/Webconverger/webc and even roll back or use branches. Not to mention enjoying all the other git compatible tooling.
Also after skimming through http://www.ubuntu.com/cloud/tools/snappy (A snappy tour of Ubuntu Core!) it seems that snappy duplicates some of the functionality of Docker.
That way clients can see the exact changes at https://github.com/Webconverger/webc and even roll back or use branches. Not to mention enjoying all the other git compatible tooling.
Also after skimming through http://www.ubuntu.com/cloud/tools/snappy (A snappy tour of Ubuntu Core!) it seems that snappy duplicates some of the functionality of Docker.