I have created this tool: https://github.com/maxadamo/g10k-zfs
The tool does the following:
- creates ZFS snapshots on an existing ZFS pool
- rotates in a loop two snapshots, called Even and Odd
- mounts either Even or Odd depending on the rotation position

• creates a new ZFS r/o snapshot whose name contains a timestamp (i.e.: code/g10k@Date-06-Jan-2020_Time-16.28.42)
• unmount the currently mounted snapshot
• mount the new snapshot
• deletes the old snapshot

This prevents leaving the code in a bad status and helps minimizing the downtime (replacing the snapshot takes few millisecond and happens only if the code was checked out successfully).

I am not sure about the question that I need to ask you, because there are actually few different options available:

1. fully integrate g10k-zfs into g10k with PR (it is version 0.1... it needs a break-in period first). I can remove docopt (which you are not using) and try to harmonize my code with g10k code.
2. we may think that the snapshot feature is not in scope with g10k. Thus, I saw initially in your code the following function: checkForAndExecutePostrunCommand(). Not clear how this works, and if it works, but g10k-zfs can be run indeed as Postrun command.
3. of course, I can run g10k first, and if g10k is successful I run g10k-zfs which will replace the snapshot