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# Copyright (C) 2018 Canonical Ltd.
#
# This file is part of cloud-init. See LICENSE file for license information.
"""Snap: Install, configure and manage snapd and snap packages."""
import sys
from textwrap import dedent
from cloudinit import log as logging
from cloudinit.config.schema import (
get_schema_doc, validate_cloudconfig_schema)
from cloudinit.settings import PER_INSTANCE
from cloudinit.subp import prepend_base_command
from cloudinit import util
distros = ['ubuntu']
frequency = PER_INSTANCE
LOG = logging.getLogger(__name__)
schema = {
'id': 'cc_snap',
'name': 'Snap',
'title': 'Install, configure and manage snapd and snap packages',
'description': dedent("""\
This module provides a simple configuration namespace in cloud-init to
both setup snapd and install snaps.
.. note::
Both ``assertions`` and ``commands`` values can be either a
dictionary or a list. If these configs are provided as a
dictionary, the keys are only used to order the execution of the
assertions or commands and the dictionary is merged with any
vendor-data snap configuration provided. If a list is provided by
the user instead of a dict, any vendor-data snap configuration is
ignored.
The ``assertions`` configuration option is a dictionary or list of
properly-signed snap assertions which will run before any snap
``commands``. They will be added to snapd's assertion database by
invoking ``snap ack <aggregate_assertion_file>``.
Snap ``commands`` is a dictionary or list of individual snap
commands to run on the target system. These commands can be used to
create snap users, install snaps and provide snap configuration.
.. note::
If 'side-loading' private/unpublished snaps on an instance, it is
best to create a snap seed directory and seed.yaml manifest in
**/var/lib/snapd/seed/** which snapd automatically installs on
startup.
**Development only**: The ``squashfuse_in_container`` boolean can be
set true to install squashfuse package when in a container to enable
snap installs. Default is false.
"""),
'distros': distros,
'examples': [dedent("""\
snap:
assertions:
00: |
signed_assertion_blob_here
02: |
signed_assertion_blob_here
commands:
00: snap create-user --sudoer --known <snap-user>@mydomain.com
01: snap install canonical-livepatch
02: canonical-livepatch enable <AUTH_TOKEN>
"""), dedent("""\
# LXC-based containers require squashfuse before snaps can be installed
snap:
commands:
00: apt-get install squashfuse -y
11: snap install emoj
"""), dedent("""\
# Convenience: the snap command can be omitted when specifying commands
# as a list and 'snap' will automatically be prepended.
# The following commands are equivalent:
snap:
commands:
00: ['install', 'vlc']
01: ['snap', 'install', 'vlc']
02: snap install vlc
03: 'snap install vlc'
""")],
'frequency': PER_INSTANCE,
'type': 'object',
'properties': {
'snap': {
'type': 'object',
'properties': {
'assertions': {
'type': ['object', 'array'], # Array of strings or dict
'items': {'type': 'string'},
'additionalItems': False, # Reject items non-string
'minItems': 1,
'minProperties': 1,
'uniqueItems': True
},
'commands': {
'type': ['object', 'array'], # Array of strings or dict
'items': {
'oneOf': [
{'type': 'array', 'items': {'type': 'string'}},
{'type': 'string'}]
},
'additionalItems': False, # Reject non-string & non-list
'minItems': 1,
'minProperties': 1,
'uniqueItems': True
},
'squashfuse_in_container': {
'type': 'boolean'
}
},
'additionalProperties': False, # Reject keys not in schema
'required': [],
'minProperties': 1
}
}
}
# TODO schema for 'assertions' and 'commands' are too permissive at the moment.
# Once python-jsonschema supports schema draft 6 add support for arbitrary
# object keys with 'patternProperties' constraint to validate string values.
__doc__ = get_schema_doc(schema) # Supplement python help()
SNAP_CMD = "snap"
ASSERTIONS_FILE = "/var/lib/cloud/instance/snapd.assertions"
def add_assertions(assertions):
"""Import list of assertions.
Import assertions by concatenating each assertion into a
string separated by a '\n'. Write this string to a instance file and
then invoke `snap ack /path/to/file` and check for errors.
If snap exits 0, then all assertions are imported.
"""
if not assertions:
return
LOG.debug('Importing user-provided snap assertions')
if isinstance(assertions, dict):
assertions = assertions.values()
elif not isinstance(assertions, list):
raise TypeError(
'assertion parameter was not a list or dict: {assertions}'.format(
assertions=assertions))
snap_cmd = [SNAP_CMD, 'ack']
combined = "\n".join(assertions)
for asrt in assertions:
LOG.debug('Snap acking: %s', asrt.split('\n')[0:2])
util.write_file(ASSERTIONS_FILE, combined.encode('utf-8'))
util.subp(snap_cmd + [ASSERTIONS_FILE], capture=True)
def run_commands(commands):
"""Run the provided commands provided in snap:commands configuration.
Commands are run individually. Any errors are collected and reported
after attempting all commands.
@param commands: A list or dict containing commands to run. Keys of a
dict will be used to order the commands provided as dict values.
"""
if not commands:
return
LOG.debug('Running user-provided snap commands')
if isinstance(commands, dict):
# Sort commands based on dictionary key
commands = [v for _, v in sorted(commands.items())]
elif not isinstance(commands, list):
raise TypeError(
'commands parameter was not a list or dict: {commands}'.format(
commands=commands))
fixed_snap_commands = prepend_base_command('snap', commands)
cmd_failures = []
for command in fixed_snap_commands:
shell = isinstance(command, str)
try:
util.subp(command, shell=shell, status_cb=sys.stderr.write)
except util.ProcessExecutionError as e:
cmd_failures.append(str(e))
if cmd_failures:
msg = 'Failures running snap commands:\n{cmd_failures}'.format(
cmd_failures=cmd_failures)
util.logexc(LOG, msg)
raise RuntimeError(msg)
# RELEASE_BLOCKER: Once LP: #1628289 is released on xenial, drop this function.
def maybe_install_squashfuse(cloud):
"""Install squashfuse if we are in a container."""
if not util.is_container():
return
try:
cloud.distro.update_package_sources()
except Exception as e:
util.logexc(LOG, "Package update failed")
raise
try:
cloud.distro.install_packages(['squashfuse'])
except Exception as e:
util.logexc(LOG, "Failed to install squashfuse")
raise
def handle(name, cfg, cloud, log, args):
cfgin = cfg.get('snap', {})
if not cfgin:
LOG.debug(("Skipping module named %s,"
" no 'snap' key in configuration"), name)
return
validate_cloudconfig_schema(cfg, schema)
if util.is_true(cfgin.get('squashfuse_in_container', False)):
maybe_install_squashfuse(cloud)
add_assertions(cfgin.get('assertions', []))
run_commands(cfgin.get('commands', []))
# vi: ts=4 expandtab
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