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# Copyright 2014-2017 Canonical Limited.
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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# http://www.apache.org/licenses/LICENSE-2.0
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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Charm helpers snap for classic charms.
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If writing reactive charms, use the snap layer:
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https://lists.ubuntu.com/archives/snapcraft/2016-September/001114.html
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from os import environ
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from time import sleep
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from charmhelpers.core.hookenv import log
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__author__ = 'Joseph Borg <joseph.borg@canonical.com>'
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SNAP_NO_LOCK = 1 # The return code for "couldn't acquire lock" in Snap (hopefully this will be improved).
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SNAP_NO_LOCK_RETRY_DELAY = 10 # Wait X seconds between Snap lock checks.
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SNAP_NO_LOCK_RETRY_COUNT = 30 # Retry to acquire the lock X times.
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class CouldNotAcquireLockException(Exception):
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def _snap_exec(commands):
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Execute snap commands.
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:param commands: List commands
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:return: Integer exit code
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assert type(commands) == list
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while return_code is None or return_code == SNAP_NO_LOCK:
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return_code = subprocess.check_call(['snap'] + commands, env=environ)
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except subprocess.CalledProcessError as e:
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if retry_count > SNAP_NO_LOCK_RETRY_COUNT:
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raise CouldNotAcquireLockException('Could not aquire lock after %s attempts' % SNAP_NO_LOCK_RETRY_COUNT)
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return_code = e.returncode
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log('Snap failed to acquire lock, trying again in %s seconds.' % SNAP_NO_LOCK_RETRY_DELAY, level='WARN')
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sleep(SNAP_NO_LOCK_RETRY_DELAY)
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def snap_install(packages, *flags):
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Install a snap package.
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:param packages: String or List String package name
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:param flags: List String flags to pass to install command
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:return: Integer return code from snap
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if type(packages) is not list:
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message = 'Installing snap(s) "%s"' % ', '.join(packages)
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message += ' with option(s) "%s"' % ', '.join(flags)
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log(message, level='INFO')
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return _snap_exec(['install'] + flags + packages)
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def snap_remove(packages, *flags):
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Remove a snap package.
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:param packages: String or List String package name
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:param flags: List String flags to pass to remove command
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:return: Integer return code from snap
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if type(packages) is not list:
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message = 'Removing snap(s) "%s"' % ', '.join(packages)
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message += ' with options "%s"' % ', '.join(flags)
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log(message, level='INFO')
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return _snap_exec(['remove'] + flags + packages)
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def snap_refresh(packages, *flags):
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Refresh / Update snap package.
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:param packages: String or List String package name
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:param flags: List String flags to pass to refresh command
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:return: Integer return code from snap
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if type(packages) is not list:
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packages = [packages]
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message = 'Refreshing snap(s) "%s"' % ', '.join(packages)
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message += ' with options "%s"' % ', '.join(flags)
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log(message, level='INFO')
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return _snap_exec(['refresh'] + flags + packages)
added
removed
hooks/charmhelpers/fetch/snap.py
