snap-helpers 0.3.0

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:

  >>> snap = snaphelpers.Snap()
  >>> snap.name
  'testapp'
  >>> snap.instance_name
  'testapp'
  >>> snap.version
  '0+git.fdf80cd'
  >>> snap.revision
  'x1'

• paths:

  >>> snap.paths.common
  PosixPath('/var/snap/testapp/common')
  >>> snap.paths.data
  PosixPath('/var/snap/testapp/x1')
  >>> snap.paths.snap
  PosixPath('/snap/testapp/x1')
  >>> snap.paths.user_common
  PosixPath('/home/ack/snap/testapp/common')
  >>> snap.paths.user_data
  PosixPath('/home/ack/snap/testapp/x1')

• snap-related environment variables:

  >>> pprint.pprint(dict(snap.environ))
  {'ARCH': 'amd64',
   'COMMON': '/var/snap/testapp/common',
   'CONTEXT': 'ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890',
   'COOKIE': 'ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890',
   'DATA': '/var/snap/testapp/x1',
   'INSTANCE_KEY': '',
   'INSTANCE_NAME': 'testapp',
   'LIBRARY_PATH': '/var/lib/snapd/lib/gl:/var/lib/snapd/lib/gl32:/var/lib/snapd/void',
   'NAME': 'testapp',
   'REEXEC': '',
   'REVISION': 'x1',
   'SNAP': '/snap/testapp/x1',
   'USER_COMMON': '/home/ack/snap/testapp/common',
   'USER_DATA': '/home/ack/snap/testapp/x1',
   'VERSION': '0+git.fdf80cd'}
  >>> snap.environ.ARCH
  'amd64'

• configuration options:

  >>> 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:

  >>> 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:

  >>> snap.metadata_files.snap
  SnapMetadataFile(/snap/snap-helpers/x3/meta/snap.yaml)
  >>> pprint(dict(snap.metadata_files.snap))
  {'apps': {'ipython': {'command': 'snap/command-chain/snapcraft-runner '
                                   '$SNAP/command-ipython.wrapper',
                        'plugs': ['home', 'network', 'network-bind']},
            'python': {'command': 'snap/command-chain/snapcraft-runner '
                                  '$SNAP/command-python.wrapper',
                       'plugs': ['home', 'network', 'network-bind']},
            'snap-helpers': {'command': 'snap/command-chain/snapcraft-runner '
                                        '$SNAP/command-snap-helpers.wrapper',
                             'plugs': ['home', 'network', 'network-bind']}},
   'architectures': ['amd64'],
   'base': 'core18',
   'confinement': 'strict',
   'description': 'Test snap for snap-helpers.\n'
                  '\n'
                  'It provides python and ipython shells to test the '
                  '`snaphelpers` library.\n',
   'grade': 'stable',
   'name': 'snap-helpers',
   'summary': 'Test snap for snap-helpers',
   'version': '0.1.6+git6.37370cd'}

setup(
    # ...
    entry_points={
        "snaphelpers.hooks": [
            "configure = testapp:configure_hook",
            "install = testapp:install_hook",
        ]
    }
)

def install_hook(snap: snaphelpers.Snap):
    # ...


def configure_hook(snap: snaphelpers.Snap):
    # ...

[options.entry_points]
snaphelpers.hooks =
    install = testapp:install_hook
    configure = testapp:configure_hook

$ snap-helpers
Python 3.6.8 (default, Aug 20 2019, 17:12:48)
Type 'copyright', 'credits' or 'license' for more information
IPython 7.8.0 -- 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': 'ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890',
 'COOKIE': 'ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890',
 'DATA': '/var/snap/snap-helpers/x1',
 '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',
 'REEXEC': '',
 'REVISION': 'x1',
 'SNAP': '/snap/snap-helpers/x1',
 'USER_COMMON': '/home/ack/snap/snap-helpers/common',
 'USER_DATA': '/home/ack/snap/snap-helpers/x1',
 'VERSION': '0.1.6+git1.4a0b997'}

$ snapcraft
$ sudo snap install --dangerous snap-helpers_*.snap

$ pip install snap-helpers