# -*- Mode:Python; indent-tabs-mode:nil; tab-width:4 -*-
#
# Copyright 2017-2021 Canonical Ltd.
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License version 3 as published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""Helpers to install snap packages."""
import contextlib
import logging
import os
import subprocess
import sys
from typing import (
Any,
Dict,
Iterator,
List,
Optional,
Sequence,
Set,
Tuple,
Union,
cast,
)
from urllib import parse
import requests
import requests_unixsocket # type: ignore
from requests import exceptions
from . import errors
# pylint: disable=line-too-long
_STORE_ASSERTION = [
"account-key",
"public-key-sha3-384=BWDEoaqyr25nF5SNCvEv2v7QnM9QsfCc0PBMYD_i2NGSQ32EF2d4D0hqUel3m8ul",
]
# pylint: enable=line-too-long
_CHANNEL_RISKS = ["stable", "candidate", "beta", "edge"]
logger = logging.getLogger(__name__)
[docs]class SnapPackage:
"""SnapPackage acts as a mediator to install or refresh a snap.
It uses information provided by snapd implicitly referring to the local
and remote stores to obtain information about the snap, such as its
confinement value and channel availability.
This information can also be used to determine if a snap should be
installed or refreshed.
There are risks of the data falling out of date between the query and the
requested action given that it is not possible to hold a global lock on
snapd and the store data can change in between validation and execution.
"""
[docs] @classmethod
def is_valid_snap(cls, snap: str) -> bool:
"""Verify whether the given snap is valid."""
return cls(snap).is_valid()
[docs] @classmethod
def is_snap_installed(cls, snap: str) -> bool:
"""Verify whether the given snap is installed."""
# Snaps are not currently supported on Windows
if sys.platform == "win32":
return False
return cls(snap).installed
def __init__(self, snap: str):
"""Lifecycle handler for a snap of the format <snap-name>/<channel>."""
self.name, self.channel = _get_parsed_snap(snap)
self._original_channel = self.channel
if not self.channel or self.channel == "stable":
self.channel = "latest/stable"
# This store information from a local request
self._local_snap_info: Optional[Dict[str, Any]] = None
# And this stores information from a remote request
self._store_snap_info: Optional[Dict[str, Any]] = None
self._is_installed: Optional[bool] = None
self._is_in_store: Optional[bool] = None
@property
def installed(self) -> bool:
"""Whether this snap is currently installed on the system."""
if self._is_installed is None:
self._is_installed = self.get_local_snap_info() is not None
return self._is_installed
@property
def in_store(self) -> bool:
"""Whether this snap is available in the store."""
if self._is_in_store is None:
try:
self._is_in_store = self.get_store_snap_info() is not None
except errors.SnapUnavailable:
self._is_in_store = False
return self._is_in_store
[docs] def get_local_snap_info(self) -> Optional[Dict[str, Any]]:
"""Return a local payload for the snap.
Validity of the results are determined by checking self.installed.
"""
if self._is_installed is None:
with contextlib.suppress(exceptions.HTTPError):
self._local_snap_info = _get_local_snap_info(self.name)
return self._local_snap_info
[docs] def get_store_snap_info(self) -> Optional[Dict[str, Any]]:
"""Return a store payload for the snap."""
if self._is_in_store is None:
# Some environments timeout often, like the armv7 testing
# infrastructure. Given that constraint, we add some retry
# logic.
retry_count = 5
while retry_count > 0:
try:
self._store_snap_info = _get_store_snap_info(self.name)
break
except exceptions.HTTPError as http_error:
logger.debug(
"The http error when checking the store for %s is %d "
"(retries left %d)",
self.name,
http_error.response.status_code,
retry_count,
)
if http_error.response.status_code == 404:
raise errors.SnapUnavailable(
snap_name=self.name, snap_channel=self.channel
)
retry_count -= 1
return self._store_snap_info
def _get_store_channels(self) -> Dict[str, Any]:
snap_store_info = self.get_store_snap_info()
if not snap_store_info or not self.in_store:
return {}
return cast(Dict[str, Any], snap_store_info["channels"])
[docs] def get_current_channel(self) -> str:
"""Obtain the current channel for this snap."""
current_channel = ""
if self.installed:
local_snap_info = self.get_local_snap_info()
if local_snap_info:
current_channel = local_snap_info["channel"]
if any(current_channel.startswith(risk) for risk in _CHANNEL_RISKS):
current_channel = f"latest/{current_channel}"
return current_channel
[docs] def has_assertions(self) -> bool:
"""Verify whether this snap has assertions."""
# A revision starting with x has been installed with
# --dangerous.
local_snap_info = self.get_local_snap_info()
if not local_snap_info:
return False
return not local_snap_info["revision"].startswith("x")
[docs] def is_classic(self) -> bool:
"""Verify whether this snap is a classic snap."""
store_channels = self._get_store_channels()
try:
return bool(store_channels[self.channel]["confinement"] == "classic")
except KeyError:
# We have seen some KeyError issues when running tests that are
# hard to debug as they only occur there, logging in debug mode
# will help uncover the root cause if it happens again.
logger.debug(
"Current store channels are %s and the store payload is %s",
store_channels,
self._store_snap_info,
)
raise
[docs] def is_valid(self) -> bool:
"""Check if the snap is valid."""
local_snap_info = self.get_local_snap_info()
if local_snap_info:
if self.installed and local_snap_info["channel"] == self.channel:
return True
if not self.in_store:
return False
store_channels = self._get_store_channels()
return self.channel in store_channels.keys()
[docs] def download(self, *, directory: Optional[str] = None) -> None:
"""Download a given snap."""
# We use the `snap download` command here on recommendation
# of the snapd team.
logger.debug("Downloading snap: %s", self.name)
snap_download_cmd = ["snap", "download", self.name]
if self._original_channel:
snap_download_cmd.extend(["--channel", self._original_channel])
try:
subprocess.run(
snap_download_cmd,
cwd=directory,
check=True,
stdout=subprocess.DEVNULL,
stderr=subprocess.DEVNULL,
)
except subprocess.CalledProcessError as err:
raise errors.SnapDownloadError(
snap_name=self.name, snap_channel=self.channel
) from err
[docs] def install(self) -> None:
"""Installs the snap onto the system."""
logger.debug("Installing snap: %s", self.name)
snap_install_cmd = ["snap", "install", self.name]
if self._original_channel:
snap_install_cmd.extend(["--channel", self._original_channel])
with contextlib.suppress(errors.SnapUnavailable, KeyError):
if self.is_classic():
snap_install_cmd.append("--classic")
try:
subprocess.run(
snap_install_cmd,
check=True,
stdout=subprocess.DEVNULL,
stderr=subprocess.DEVNULL,
)
except subprocess.CalledProcessError as err:
raise errors.SnapInstallError(
snap_name=self.name, snap_channel=self.channel
) from err
# Now that the snap is installed, invalidate the data we had on it.
self._is_installed = None
[docs] def refresh(self) -> None:
"""Refresh a snap onto a channel on the system."""
logger.debug("Refreshing snap: %s (channel %s)", self.name, self.channel)
snap_refresh_cmd = ["snap", "refresh", self.name, "--channel", self.channel]
with contextlib.suppress(errors.SnapUnavailable, KeyError):
if self.is_classic():
snap_refresh_cmd.append("--classic")
try:
subprocess.run(
snap_refresh_cmd,
check=True,
stdout=subprocess.DEVNULL,
stderr=subprocess.DEVNULL,
)
except subprocess.CalledProcessError as err:
raise errors.SnapRefreshError(
snap_name=self.name, snap_channel=self.channel
) from err
# Now that the snap is refreshed, invalidate the data we had on it.
self._is_installed = None
[docs]def download_snaps(*, snaps_list: Sequence[str], directory: str) -> None:
"""Download snaps of the format <snap-name>/<channel> into directory.
The target directory is created if it does not exist.
"""
os.makedirs(directory, exist_ok=True)
for snap in snaps_list:
snap_pkg = SnapPackage(snap)
logger.debug("Downloading snap %s", snap_pkg.name)
snap_pkg.download(directory=directory)
[docs]def install_snaps(snaps_list: Union[Sequence[str], Set[str]]) -> List[str]:
"""Install snaps of the format <snap-name>/<channel>.
:return: a list of "name=revision" for the snaps installed.
"""
snaps_installed = []
for snap in snaps_list:
snap_pkg = SnapPackage(snap)
store_snap_info = snap_pkg.get_store_snap_info()
if store_snap_info:
# Allow bases to be installed from non stable channels.
snap_pkg_channel = store_snap_info["channel"]
snap_pkg_type = store_snap_info["type"]
if snap_pkg_channel != "stable" and snap_pkg_type == "base":
snap_pkg = SnapPackage(f"{snap_pkg.name}/latest/{snap_pkg_channel}")
if not snap_pkg.installed:
snap_pkg.install()
local_snap_info = snap_pkg.get_local_snap_info()
if local_snap_info:
snaps_installed.append(f'{snap_pkg.name}={local_snap_info["revision"]}')
return snaps_installed
[docs]def get_assertion(assertion_params: Sequence[str]) -> bytes:
"""Get assertion information.
:param assertion_params: a sequence of strings to pass to 'snap known'.
:returns: a stream of bytes from the assertion.
:rtype: bytes
"""
try:
return subprocess.check_output(["snap", "known", *assertion_params])
except subprocess.CalledProcessError as call_error:
raise errors.SnapGetAssertionError(
assertion_params=assertion_params
) from call_error
def _get_parsed_snap(snap: str) -> Tuple[str, str]:
if "/" in snap:
sep_index = snap.find("/")
snap_name = snap[:sep_index]
snap_channel = snap[sep_index + 1 :]
else:
snap_name = snap
snap_channel = ""
return snap_name, snap_channel
[docs]def get_snapd_socket_path_template() -> str:
"""Return the template for the snapd socket URI."""
return "http+unix://%2Frun%2Fsnapd.socket/v2/{}"
def _get_local_snap_file_iter(snap_name: str, *, chunk_size: int) -> Iterator[bytes]:
slug = f'snaps/{parse.quote(snap_name, safe="")}/file'
url = get_snapd_socket_path_template().format(slug)
try:
snap_file: requests.Response = requests_unixsocket.get(url)
except exceptions.ConnectionError as err:
raise errors.SnapdConnectionError(snap_name=snap_name, url=url) from err
snap_file.raise_for_status()
return snap_file.iter_content(chunk_size)
def _get_local_snap_info(snap_name: str) -> Dict[str, Any]:
slug = f'snaps/{parse.quote(snap_name, safe="")}'
url = get_snapd_socket_path_template().format(slug)
try:
snap_info = requests_unixsocket.get(url)
except exceptions.ConnectionError as err:
raise errors.SnapdConnectionError(snap_name=snap_name, url=url) from err
snap_info.raise_for_status()
return cast(Dict[str, Any], snap_info.json()["result"])
def _get_store_snap_info(snap_name: str) -> Dict[str, Any]:
# This logic uses /v2/find returns an array of results, given that
# we do a strict search either 1 result or a 404 will be returned.
slug = f"find?{parse.urlencode({'name': snap_name})}"
url = get_snapd_socket_path_template().format(slug)
snap_info = requests_unixsocket.get(url)
snap_info.raise_for_status()
return cast(Dict[str, Any], snap_info.json()["result"][0])
[docs]def get_installed_snaps() -> List[str]:
"""Return all the snaps installed in the system.
:return: a list of "name=revision" for the snaps installed.
"""
slug = "snaps"
url = get_snapd_socket_path_template().format(slug)
try:
snap_info = requests_unixsocket.get(url)
snap_info.raise_for_status()
local_snaps = snap_info.json()["result"]
except exceptions.ConnectionError:
local_snaps = []
return [f'{snap["name"]}={snap["revision"]}' for snap in local_snaps]
