simplezfs 0.0.3

Description:

simplezfs 0.0.3

A thin wrapper around ZFS from the OpenZFS project.
The library aims at providing a simple, low-level interface for working with ZFS, either by wrapping the zfs(8) and
zpool(8) CLI utilities or by accessing the native python API.
It does not provide a high-level interface, however, and does not aim to. It also tries to keep as little state as
possible.
Two interface classes make up the API, ZFS and ZPool, which are wrappers around the functionality of the CLI
tools of the same name. They come with two implementations:

The CLI implementation wraps the executables
The Native implementation uses the native API released with OpenZFS 0.8.

In this early stage, the native implementation has not been written.

Status
The table gives a rough overview over features and their implementation state. For the PE Helper, functions where it is
of no use are left empty (use zfs allow for those). Recursive is used to denote if it can destroy the dataset with
dependent datasets, for example a fileset with its associated snapshots.


API
Topic
Feature
CLI
Native
PE Helper
Recursive



ZFS
Properties
Read native
Yes
No



Write native
Yes
No



Read metadata
Yes
No



Write metadata
Yes
No



Datasets
List datasets
Yes
No



Check existance
Yes
No



Create Fileset
Yes
No
Yes


Create Volume
No
No



Create Snapshot
No
No
No


Create Bookmark
No
No



Destroy Fileset
Yes
No
Yes
Yes (Snaps)

Destroy Volume
No
No
No


Destroy Snapshot
No
No
No


Destroy Bookmark
No
No
No


ZPool
Storage
List pools
No
No



Read structure
Yes
No



Replace disk
No
No
No


Destroy
No
No
No


Create
No
No
No


Properties
Read native
No
No



Write native
No
No
No


Read metadata
No
No



Write metadata
No
No







Usage
One can either get a concrete implementation by calling ZFSCli/ZFSNative or ZPoolCli/ZPoolNative, or
more conveniently use the functions get_zfs(implementation_name) or get_zpool(implementation_name).
First, get an instance:
>>> from simplezfs import get_zfs
>>> zfs = get_zfs('cli') # or "native" for the native API
>>> zfs
<simplezfs.zfs_cli.ZFSCli object at 0x7ffbca7fb9e8>
>>>
>>> for ds in zfs.list_datasets():
... print(ds.name)
...
tank
tank/system
tank/system/rootfs


Compatibility
The library is written with Python 3.6 or higher in mind, which was in a stable release in a few of the major Linux
distributions we care about (Debian Buster, Ubuntu 18.04 LTS, RHEL 8, Gentoo).
On the OpenZFS side, the code is developed on version 0.8 and newer, and takes some validation values from that
release. The library doesn’t make a lot of assumptions, the code should work on 0.7, too. If you spot an
incompatibility, please let us know via the issue tracker.


Testing
An extensive set of tests are in the tests/ subfolder, it can be run using pytest from the source of the
repository. At this time, only the validation functions and the ZFS Cli API are tested, the tests are non-destructive
and won’t run the actual commands but instead mock away the subprocess invocations and supply dummy commands to run
(usually /bin/true) should the code be changed in a way that isn’t caught by the test framework. Nevertheless, keep
in mind that if commands are run for whatever reason, they most likely result in unrecoverable data loss.
It is planned to add a separate set of destructive tests that need to be specially activated for testing if the code
works when run against an actual Linux system. This can’t be done using most of the CI providers, as the nature of ZFS
requires having a operating system with loaded modules that may be destroyed during the test run.