snapzap

snapzap is a command-line utility for listing and pruning ZFS snapshots with ease and efficiency. Unlike traditional methods that rely on calling external zfs and zpool commands, snapzap leverages the libzfs library directly.

I built this because I didn't feel comfortable with the fact that the zfs destroy command has no way of filtering zfs types for destruction. This makes scripting a bit dangerous, with so many possible footguns that could cause the wrong arguments to get passed to the command and result in data loss.

Key Features:

• Snapshot Management: snapzap provides a streamlined interface for listing, filtering, and deleting ZFS snapshots that works well for automation with cronjobs or systemd timers.
• Direct Integration with ZFS: By utilizing the libzfs library, snapzap offers direct integration with ZFS, eliminating the need for intermediate shell commands or risky grep or xargs mistakes.
• Safe and Reliable: snapzap ensures the safe deletion of snapshots, guarding against accidental deletion of critical datasets by only calling libzfs functions that delete snapshots or using zfs handles directly.
• Does not filter by snapshot names: Filters can be guids, creation dates, even user properties (custom properties containing :). Not filtering by snapshot names is an intentional design choice.

snapzap aims to simplify ZFS snapshot pruning without the possiblility of deleting datasets.

Building:

snapzap requires libzfs and libspl (typically included with zfs-utils). Use make to use the included Makefile to build with cmake and make install with elevated privileges to install. If cmake isn't installed, it can be compiled with make snapzap instead. Other Makefile targets include clean, check (using cppcheck), and tidy (using clang-format and clang-tidy).

Currently builds with OpenZFS 2.2.2 on Linux, work is being done to port it to FreeBSD.

Examples:

Example systemd scripts are included in the examples directory for daily and weekly systemd timers and services.

Usage

Usage: snapzap <dataset> [options]
Options:
  --filter=<property=value>    Filter by ZFS property
  --before=<epoch timestamp>   Filter snapshots created before the timestamp
  --after=<epoch timestamp>    Filter snapshots created after the timestamp
  --delete                     Delete matching snapshots
Subshells with the `date` command can be used for epoch timestamps:
	--after=$(date -d 'jan 1 2024' +%s)
	--before=$(date -d 'today -30 days' +%s)

snapzap tank --before $(date -d "today -20 days" +%%s) --filter custom:property=custom_value --delete --recursive

snapzap tank --filter guid=18201047423112093010 --delete

snapzap tank/dataset --before $(date -d "jan 1 2024" +%s)