snap-helpers - Interact with the Snap system within a Snap
|Latest Version| |Snap Package| |Build Status| |Coverage Status| |Documentation|
A Python library to interact with snap configuration and properties from inside
a snap.
It exposes a top-level snaphelpers.Snap
object which provides access to:
-
snap details:
.. code:: python
snap = snaphelpers.Snap()
snap.name
'snap-helpers'
snap.instance_name
'snap-helpers'
snap.version
'0.3.0+git5.5794660'
snap.revision
'138'
-
paths:
.. code:: python
snap.paths.common
PosixPath('/var/snap/snap-helpers/common')
snap.paths.data
PosixPath('/var/snap/snap-helpers/138')
snap.paths.real_home
PosixPath('/home/ack')
snap.paths.snap
PosixPath('/snap/snap-helpers/138')
snap.paths.user_common
PosixPath('/home/ack/snap/snap-helpers/common')
snap.paths.user_data
PosixPath('/home/ack/snap/snap-helpers/138')
-
snap-related environment variables:
.. code:: python
pprint.pprint(dict(snap.environ))
{'ARCH': 'amd64',
'COMMON': '/var/snap/snap-helpers/common',
'CONTEXT': 'XbhAD8QBMDwJiEi5LcN-5fCrVeAG7qBGojWiWA0vXkx0hX-JxyqX',
'COOKIE': 'XbhAD8QBMDwJiEi5LcN-5fCrVeAG7qBGojWiWA0vXkx0hX-JxyqX',
'DATA': '/var/snap/snap-helpers/138',
'INSTANCE_KEY': '',
'INSTANCE_NAME': 'snap-helpers',
'LIBRARY_PATH': '/var/lib/snapd/lib/gl:/var/lib/snapd/lib/gl32:/var/lib/snapd/void',
'NAME': 'snap-helpers',
'REAL_HOME': '/home/ack',
'REEXEC': '',
'REVISION': '138',
'SNAP': '/snap/snap-helpers/138',
'USER_COMMON': '/home/ack/snap/snap-helpers/common',
'USER_DATA': '/home/ack/snap/snap-helpers/138',
'VERSION': '0.3.0+git5.5794660'}
snap.environ.ARCH
'amd64'
-
configuration options:
.. code:: python
snap.config.set({'foo.bar': 'baz', 'asdf': 3}) # this needs to be run as root
options = snap.config.get_options('foo', 'asdf')
options['foo']
{'bar': 'baz'}
options['foo.bar']
'baz'
options['asdf']
3
options.as_dict()
{'asdf': 3, 'foo': {'bar': 'baz'}}
-
setting snap health status, along with message and optional status code:
.. code:: python
snap.health.okay()
snap.health.waiting('foo must happen first', code='wait-foo')
Health status (when different from okay
) is visible from the snap
CLI::
$ snap info snap-helpers
name: snap-helpers
summary: Test snap for snap-helpers
health:
status: waiting
message: foo must happen first
code: wait-foo
checked: today at 16:23 CEST
-
content of snap metadata files such as:
snap/metadata.yaml
meta/snap.yaml
snap/snapcraft.yaml
These can be accessed as follows:
.. code:: python
snap.metadata_files.snap
SnapMetadataFile(/snap/snap-helpers/138/meta/snap.yaml)
snap.metadata_files.snap.path
PosixPath('/snap/snap-helpers/138/meta/snap.yaml')
snap.metadata_files.snap["name"]
'snap-helpers'
snap.metadata_files.snap["base"]
'core22'
pprint.pprint(dict(snap.metadata_files.snap))
{'apps': {'python': {'command': 'bin/python3',
'plugs': ['home', 'network', 'network-bind']},
'snap-helpers': {'command': 'bin/snap-helpers-shell',
'plugs': ['home', 'network', 'network-bind']}},
'architectures': ['amd64'],
'base': 'core22',
'confinement': 'strict',
'description': 'Test snap for the snap-helpers Python library.\n'
'\n'
'It provides python and ipython shells to interact and test '
'the snaphelpers
\n'
'library.\n'
'\n'
'See the https://github.com/albertodonato/snap-helpers for '
'more details.\n',
'environment': {'LD_LIBRARY_PATH': '${SNAP_LIBRARY_PATH}${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}:$SNAP/lib',
'PATH': '$SNAP/usr/sbin:$SNAP/usr/bin:$SNAP/sbin:$SNAP/bin:$PATH'},
'grade': 'stable',
'license': 'LGPL-3.0',
'name': 'snap-helpers',
'slots': {'snap-helpers-lib': {'content': 'snap-helpers-lib',
'interface': 'content',
'read': ['$SNAP/lib/python3.10/site-packages/snaphelpers']}},
'summary': 'Test snap for the snap-helpers Python library.',
'version': '0.3.0+git5.5794660'}
Hook helpers
The library provides helpers to reduce boilerplate when setting up hooks for
the snap, by using entry-points
in the package metadata.
This can be done in setup.py
:
.. code:: python
setup(
# ...
entry_points={
"snaphelpers.hooks": [
"configure = testapp:configure_hook",
"install = testapp:install_hook",
]
}
)
or in setup.cfg
:
.. code:: ini
[options.entry_points]
snaphelpers.hooks =
configure = testapp:configure_hook
install = testapp:install_hook
or in pyproject.toml
:
.. code:: toml
[project.entry-points."snaphelpers.hooks"]
configure = "testapp:configure_hook"
install = "testapp:install_hook"
Hook functions are called with a Snap
object as argument:
.. code:: python
def install_hook(snap: snaphelpers.Snap):
# ...
def configure_hook(snap: snaphelpers.Snap):
# ...
snap-helpers
will take care of the hooks plumbing (i.e. creating hook files
in $SNAP/snap/hooks
).
Supported snap bases
Currently supported snap bases are:
core20
(Python 3.8)core22
(Python 3.10)
The core18
base (with Python 3.6) is supported until the 0.3.2
release.
Testing with the snap
The snap-helpers
snap provides a way to easily test code using the library
in a real snap environment with strict confinement.
It provides an IPython_ shell which automatically imports the snaphelpers
module and provides a Snap
instance for the current snap.
.. code::
$ snap-helpers
Python 3.10.4 (main, Jun 29 2022, 12:14:53) [GCC 11.2.0]
Type 'copyright', 'credits' or 'license' for more information
IPython 8.7.0 -- An enhanced Interactive Python. Type '?' for help.
Use the "snap" variable for an instance for the current snap.
In [1]: import pprint
In [2]: pprint.pprint(dict(snap.environ))
{'ARCH': 'amd64',
'COMMON': '/var/snap/snap-helpers/common',
'CONTEXT': 'XbhAD8QBMDwJiEi5LcN-5fCrVeAG7qBGojWiWA0vXkx0hX-JxyqX',
'COOKIE': 'XbhAD8QBMDwJiEi5LcN-5fCrVeAG7qBGojWiWA0vXkx0hX-JxyqX',
'DATA': '/var/snap/snap-helpers/138',
'INSTANCE_KEY': '',
'INSTANCE_NAME': 'snap-helpers',
'LIBRARY_PATH': '/var/lib/snapd/lib/gl:/var/lib/snapd/lib/gl32:/var/lib/snapd/void',
'NAME': 'snap-helpers',
'REAL_HOME': '/home/ack',
'REEXEC': '',
'REVISION': '138',
'SNAP': '/snap/snap-helpers/138',
'USER_COMMON': '/home/ack/snap/snap-helpers/common',
'USER_DATA': '/home/ack/snap/snap-helpers/138',
'VERSION': '0.3.0+git5.5794660'}
The snap can be built and installed as follows:
.. code:: shell
$ snapcraft -v
$ sudo snap install --dangerous snap-helpers_*.snap
Installation
snap-helpers
can be installed from PyPI_.
Run:
.. code:: shell
$ pip install snap-helpers
Documentation
Full documentation is available on ReadTheDocs_.
.. _IPython: https://ipython.org/
.. _PyPI: https://pypi.org/
.. _ReadTheDocs: https://snap-helpers.readthedocs.io/en/latest/
.. |Latest Version| image:: https://img.shields.io/pypi/v/snap-helpers.svg
:alt: Latest Version
:target: https://pypi.python.org/pypi/snap-helpers
.. |Snap Package| image:: https://snapcraft.io/snap-helpers/badge.svg
:alt: Snap Package
:target: https://snapcraft.io/snap-helpers
.. |Build Status| image:: https://github.com/albertodonato/snap-helpers/workflows/CI/badge.svg
:alt: Build Status
:target: https://github.com/albertodonato/snap-helpers/actions?query=workflow%3ACI
.. |Coverage Status| image:: https://img.shields.io/codecov/c/github/albertodonato/snap-helpers/main.svg
:alt: Coverage Status
:target: https://codecov.io/gh/albertodonato/snap-helpers
.. |Documentation| image:: https://readthedocs.org/projects/snap-helpers/badge/?version=stable
:alt: Documentation
:target: https://snap-helpers.readthedocs.io/en/stable/?badge=stable