# Copyright 2014-2015 Canonical Limited.
#
# This file is part of charm-helpers.
#
# charm-helpers 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.
#
# charm-helpers 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 charm-helpers. If not, see .
"Interactions with the Juju environment"
# Copyright 2013 Canonical Ltd.
#
# Authors:
# Charm Helpers Developers
from __future__ import print_function
from functools import wraps
import os
import json
import yaml
import subprocess
import sys
import errno
import tempfile
from subprocess import CalledProcessError
import six
if not six.PY3:
from UserDict import UserDict
else:
from collections import UserDict
CRITICAL = "CRITICAL"
ERROR = "ERROR"
WARNING = "WARNING"
INFO = "INFO"
DEBUG = "DEBUG"
MARKER = object()
cache = {}
def cached(func):
"""Cache return values for multiple executions of func + args
For example::
@cached
def unit_get(attribute):
pass
unit_get('test')
will cache the result of unit_get + 'test' for future calls.
"""
@wraps(func)
def wrapper(*args, **kwargs):
global cache
key = str((func, args, kwargs))
try:
return cache[key]
except KeyError:
pass # Drop out of the exception handler scope.
res = func(*args, **kwargs)
cache[key] = res
return res
return wrapper
def flush(key):
"""Flushes any entries from function cache where the
key is found in the function+args """
flush_list = []
for item in cache:
if key in item:
flush_list.append(item)
for item in flush_list:
del cache[item]
def log(message, level=None):
"""Write a message to the juju log"""
command = ['juju-log']
if level:
command += ['-l', level]
if not isinstance(message, six.string_types):
message = repr(message)
command += [message]
# Missing juju-log should not cause failures in unit tests
# Send log output to stderr
try:
subprocess.call(command)
except OSError as e:
if e.errno == errno.ENOENT:
if level:
message = "{}: {}".format(level, message)
message = "juju-log: {}".format(message)
print(message, file=sys.stderr)
else:
raise
class Serializable(UserDict):
"""Wrapper, an object that can be serialized to yaml or json"""
def __init__(self, obj):
# wrap the object
UserDict.__init__(self)
self.data = obj
def __getattr__(self, attr):
# See if this object has attribute.
if attr in ("json", "yaml", "data"):
return self.__dict__[attr]
# Check for attribute in wrapped object.
got = getattr(self.data, attr, MARKER)
if got is not MARKER:
return got
# Proxy to the wrapped object via dict interface.
try:
return self.data[attr]
except KeyError:
raise AttributeError(attr)
def __getstate__(self):
# Pickle as a standard dictionary.
return self.data
def __setstate__(self, state):
# Unpickle into our wrapper.
self.data = state
def json(self):
"""Serialize the object to json"""
return json.dumps(self.data)
def yaml(self):
"""Serialize the object to yaml"""
return yaml.dump(self.data)
def execution_environment():
"""A convenient bundling of the current execution context"""
context = {}
context['conf'] = config()
if relation_id():
context['reltype'] = relation_type()
context['relid'] = relation_id()
context['rel'] = relation_get()
context['unit'] = local_unit()
context['rels'] = relations()
context['env'] = os.environ
return context
def in_relation_hook():
"""Determine whether we're running in a relation hook"""
return 'JUJU_RELATION' in os.environ
def relation_type():
"""The scope for the current relation hook"""
return os.environ.get('JUJU_RELATION', None)
def relation_id():
"""The relation ID for the current relation hook"""
return os.environ.get('JUJU_RELATION_ID', None)
def local_unit():
"""Local unit ID"""
return os.environ['JUJU_UNIT_NAME']
def remote_unit():
"""The remote unit for the current relation hook"""
return os.environ.get('JUJU_REMOTE_UNIT', None)
def service_name():
"""The name service group this unit belongs to"""
return local_unit().split('/')[0]
def hook_name():
"""The name of the currently executing hook"""
return os.path.basename(sys.argv[0])
class Config(dict):
"""A dictionary representation of the charm's config.yaml, with some
extra features:
- See which values in the dictionary have changed since the previous hook.
- For values that have changed, see what the previous value was.
- Store arbitrary data for use in a later hook.
NOTE: Do not instantiate this object directly - instead call
``hookenv.config()``, which will return an instance of :class:`Config`.
Example usage::
>>> # inside a hook
>>> from charmhelpers.core import hookenv
>>> config = hookenv.config()
>>> config['foo']
'bar'
>>> # store a new key/value for later use
>>> config['mykey'] = 'myval'
>>> # user runs `juju set mycharm foo=baz`
>>> # now we're inside subsequent config-changed hook
>>> config = hookenv.config()
>>> config['foo']
'baz'
>>> # test to see if this val has changed since last hook
>>> config.changed('foo')
True
>>> # what was the previous value?
>>> config.previous('foo')
'bar'
>>> # keys/values that we add are preserved across hooks
>>> config['mykey']
'myval'
"""
CONFIG_FILE_NAME = '.juju-persistent-config'
def __init__(self, *args, **kw):
super(Config, self).__init__(*args, **kw)
self.implicit_save = True
self._prev_dict = None
self.path = os.path.join(charm_dir(), Config.CONFIG_FILE_NAME)
if os.path.exists(self.path):
self.load_previous()
def __getitem__(self, key):
"""For regular dict lookups, check the current juju config first,
then the previous (saved) copy. This ensures that user-saved values
will be returned by a dict lookup.
"""
try:
return dict.__getitem__(self, key)
except KeyError:
return (self._prev_dict or {})[key]
def get(self, key, default=None):
try:
return self[key]
except KeyError:
return default
def keys(self):
prev_keys = []
if self._prev_dict is not None:
prev_keys = self._prev_dict.keys()
return list(set(prev_keys + list(dict.keys(self))))
def load_previous(self, path=None):
"""Load previous copy of config from disk.
In normal usage you don't need to call this method directly - it
is called automatically at object initialization.
:param path:
File path from which to load the previous config. If `None`,
config is loaded from the default location. If `path` is
specified, subsequent `save()` calls will write to the same
path.
"""
self.path = path or self.path
with open(self.path) as f:
self._prev_dict = json.load(f)
def changed(self, key):
"""Return True if the current value for this key is different from
the previous value.
"""
if self._prev_dict is None:
return True
return self.previous(key) != self.get(key)
def previous(self, key):
"""Return previous value for this key, or None if there
is no previous value.
"""
if self._prev_dict:
return self._prev_dict.get(key)
return None
def save(self):
"""Save this config to disk.
If the charm is using the :mod:`Services Framework `
or :meth:'@hook ' decorator, this
is called automatically at the end of successful hook execution.
Otherwise, it should be called directly by user code.
To disable automatic saves, set ``implicit_save=False`` on this
instance.
"""
if self._prev_dict:
for k, v in six.iteritems(self._prev_dict):
if k not in self:
self[k] = v
with open(self.path, 'w') as f:
json.dump(self, f)
@cached
def config(scope=None):
"""Juju charm configuration"""
config_cmd_line = ['config-get']
if scope is not None:
config_cmd_line.append(scope)
config_cmd_line.append('--format=json')
try:
config_data = json.loads(
subprocess.check_output(config_cmd_line).decode('UTF-8'))
if scope is not None:
return config_data
return Config(config_data)
except ValueError:
return None
@cached
def relation_get(attribute=None, unit=None, rid=None):
"""Get relation information"""
_args = ['relation-get', '--format=json']
if rid:
_args.append('-r')
_args.append(rid)
_args.append(attribute or '-')
if unit:
_args.append(unit)
try:
return json.loads(subprocess.check_output(_args).decode('UTF-8'))
except ValueError:
return None
except CalledProcessError as e:
if e.returncode == 2:
return None
raise
def relation_set(relation_id=None, relation_settings=None, **kwargs):
"""Set relation information for the current unit"""
relation_settings = relation_settings if relation_settings else {}
relation_cmd_line = ['relation-set']
accepts_file = "--file" in subprocess.check_output(
relation_cmd_line + ["--help"], universal_newlines=True)
if relation_id is not None:
relation_cmd_line.extend(('-r', relation_id))
settings = relation_settings.copy()
settings.update(kwargs)
for key, value in settings.items():
# Force value to be a string: it always should, but some call
# sites pass in things like dicts or numbers.
if value is not None:
settings[key] = "{}".format(value)
if accepts_file:
# --file was introduced in Juju 1.23.2. Use it by default if
# available, since otherwise we'll break if the relation data is
# too big. Ideally we should tell relation-set to read the data from
# stdin, but that feature is broken in 1.23.2: Bug #1454678.
with tempfile.NamedTemporaryFile(delete=False) as settings_file:
settings_file.write(yaml.safe_dump(settings).encode("utf-8"))
subprocess.check_call(
relation_cmd_line + ["--file", settings_file.name])
os.remove(settings_file.name)
else:
for key, value in settings.items():
if value is None:
relation_cmd_line.append('{}='.format(key))
else:
relation_cmd_line.append('{}={}'.format(key, value))
subprocess.check_call(relation_cmd_line)
# Flush cache of any relation-gets for local unit
flush(local_unit())
def relation_clear(r_id=None):
''' Clears any relation data already set on relation r_id '''
settings = relation_get(rid=r_id,
unit=local_unit())
for setting in settings:
if setting not in ['public-address', 'private-address']:
settings[setting] = None
relation_set(relation_id=r_id,
**settings)
@cached
def relation_ids(reltype=None):
"""A list of relation_ids"""
reltype = reltype or relation_type()
relid_cmd_line = ['relation-ids', '--format=json']
if reltype is not None:
relid_cmd_line.append(reltype)
return json.loads(
subprocess.check_output(relid_cmd_line).decode('UTF-8')) or []
return []
@cached
def related_units(relid=None):
"""A list of related units"""
relid = relid or relation_id()
units_cmd_line = ['relation-list', '--format=json']
if relid is not None:
units_cmd_line.extend(('-r', relid))
return json.loads(
subprocess.check_output(units_cmd_line).decode('UTF-8')) or []
@cached
def relation_for_unit(unit=None, rid=None):
"""Get the json represenation of a unit's relation"""
unit = unit or remote_unit()
relation = relation_get(unit=unit, rid=rid)
for key in relation:
if key.endswith('-list'):
relation[key] = relation[key].split()
relation['__unit__'] = unit
return relation
@cached
def relations_for_id(relid=None):
"""Get relations of a specific relation ID"""
relation_data = []
relid = relid or relation_ids()
for unit in related_units(relid):
unit_data = relation_for_unit(unit, relid)
unit_data['__relid__'] = relid
relation_data.append(unit_data)
return relation_data
@cached
def relations_of_type(reltype=None):
"""Get relations of a specific type"""
relation_data = []
reltype = reltype or relation_type()
for relid in relation_ids(reltype):
for relation in relations_for_id(relid):
relation['__relid__'] = relid
relation_data.append(relation)
return relation_data
@cached
def metadata():
"""Get the current charm metadata.yaml contents as a python object"""
with open(os.path.join(charm_dir(), 'metadata.yaml')) as md:
return yaml.safe_load(md)
@cached
def relation_types():
"""Get a list of relation types supported by this charm"""
rel_types = []
md = metadata()
for key in ('provides', 'requires', 'peers'):
section = md.get(key)
if section:
rel_types.extend(section.keys())
return rel_types
@cached
def charm_name():
"""Get the name of the current charm as is specified on metadata.yaml"""
return metadata().get('name')
@cached
def relations():
"""Get a nested dictionary of relation data for all related units"""
rels = {}
for reltype in relation_types():
relids = {}
for relid in relation_ids(reltype):
units = {local_unit(): relation_get(unit=local_unit(), rid=relid)}
for unit in related_units(relid):
reldata = relation_get(unit=unit, rid=relid)
units[unit] = reldata
relids[relid] = units
rels[reltype] = relids
return rels
@cached
def is_relation_made(relation, keys='private-address'):
'''
Determine whether a relation is established by checking for
presence of key(s). If a list of keys is provided, they
must all be present for the relation to be identified as made
'''
if isinstance(keys, str):
keys = [keys]
for r_id in relation_ids(relation):
for unit in related_units(r_id):
context = {}
for k in keys:
context[k] = relation_get(k, rid=r_id,
unit=unit)
if None not in context.values():
return True
return False
def open_port(port, protocol="TCP"):
"""Open a service network port"""
_args = ['open-port']
_args.append('{}/{}'.format(port, protocol))
subprocess.check_call(_args)
def close_port(port, protocol="TCP"):
"""Close a service network port"""
_args = ['close-port']
_args.append('{}/{}'.format(port, protocol))
subprocess.check_call(_args)
@cached
def unit_get(attribute):
"""Get the unit ID for the remote unit"""
_args = ['unit-get', '--format=json', attribute]
try:
return json.loads(subprocess.check_output(_args).decode('UTF-8'))
except ValueError:
return None
def unit_public_ip():
"""Get this unit's public IP address"""
return unit_get('public-address')
def unit_private_ip():
"""Get this unit's private IP address"""
return unit_get('private-address')
class UnregisteredHookError(Exception):
"""Raised when an undefined hook is called"""
pass
class Hooks(object):
"""A convenient handler for hook functions.
Example::
hooks = Hooks()
# register a hook, taking its name from the function name
@hooks.hook()
def install():
pass # your code here
# register a hook, providing a custom hook name
@hooks.hook("config-changed")
def config_changed():
pass # your code here
if __name__ == "__main__":
# execute a hook based on the name the program is called by
hooks.execute(sys.argv)
"""
def __init__(self, config_save=True):
super(Hooks, self).__init__()
self._hooks = {}
self._config_save = config_save
def register(self, name, function):
"""Register a hook"""
self._hooks[name] = function
def execute(self, args):
"""Execute a registered hook based on args[0]"""
hook_name = os.path.basename(args[0])
if hook_name in self._hooks:
self._hooks[hook_name]()
if self._config_save:
cfg = config()
if cfg.implicit_save:
cfg.save()
else:
raise UnregisteredHookError(hook_name)
def hook(self, *hook_names):
"""Decorator, registering them as hooks"""
def wrapper(decorated):
for hook_name in hook_names:
self.register(hook_name, decorated)
else:
self.register(decorated.__name__, decorated)
if '_' in decorated.__name__:
self.register(
decorated.__name__.replace('_', '-'), decorated)
return decorated
return wrapper
def charm_dir():
"""Return the root directory of the current charm"""
return os.environ.get('CHARM_DIR')
@cached
def action_get(key=None):
"""Gets the value of an action parameter, or all key/value param pairs"""
cmd = ['action-get']
if key is not None:
cmd.append(key)
cmd.append('--format=json')
action_data = json.loads(subprocess.check_output(cmd).decode('UTF-8'))
return action_data
def action_set(values):
"""Sets the values to be returned after the action finishes"""
cmd = ['action-set']
for k, v in list(values.items()):
cmd.append('{}={}'.format(k, v))
subprocess.check_call(cmd)
def action_fail(message):
"""Sets the action status to failed and sets the error message.
The results set by action_set are preserved."""
subprocess.check_call(['action-fail', message])
def status_set(workload_state, message):
"""Set the workload state with a message
Use status-set to set the workload state with a message which is visible
to the user via juju status. If the status-set command is not found then
assume this is juju < 1.23 and juju-log the message unstead.
workload_state -- valid juju workload state.
message -- status update message
"""
valid_states = ['maintenance', 'blocked', 'waiting', 'active']
if workload_state not in valid_states:
raise ValueError(
'{!r} is not a valid workload state'.format(workload_state)
)
cmd = ['status-set', workload_state, message]
try:
ret = subprocess.call(cmd)
if ret == 0:
return
except OSError as e:
if e.errno != errno.ENOENT:
raise
log_message = 'status-set failed: {} {}'.format(workload_state,
message)
log(log_message, level='INFO')
def status_get():
"""Retrieve the previously set juju workload state
If the status-set command is not found then assume this is juju < 1.23 and
return 'unknown'
"""
cmd = ['status-get']
try:
raw_status = subprocess.check_output(cmd, universal_newlines=True)
status = raw_status.rstrip()
return status
except OSError as e:
if e.errno == errno.ENOENT:
return 'unknown'
else:
raise
def translate_exc(from_exc, to_exc):
def inner_translate_exc1(f):
def inner_translate_exc2(*args, **kwargs):
try:
return f(*args, **kwargs)
except from_exc:
raise to_exc
return inner_translate_exc2
return inner_translate_exc1
@translate_exc(from_exc=OSError, to_exc=NotImplementedError)
def is_leader():
"""Does the current unit hold the juju leadership
Uses juju to determine whether the current unit is the leader of its peers
"""
cmd = ['is-leader', '--format=json']
return json.loads(subprocess.check_output(cmd).decode('UTF-8'))
@translate_exc(from_exc=OSError, to_exc=NotImplementedError)
def leader_get(attribute=None):
"""Juju leader get value(s)"""
cmd = ['leader-get', '--format=json'] + [attribute or '-']
return json.loads(subprocess.check_output(cmd).decode('UTF-8'))
@translate_exc(from_exc=OSError, to_exc=NotImplementedError)
def leader_set(settings=None, **kwargs):
"""Juju leader set value(s)"""
log("Juju leader-set '%s'" % (settings), level=DEBUG)
cmd = ['leader-set']
settings = settings or {}
settings.update(kwargs)
for k, v in settings.iteritems():
if v is None:
cmd.append('{}='.format(k))
else:
cmd.append('{}={}'.format(k, v))
subprocess.check_call(cmd)