/usr/share/pyshared/juju/charm/metadata.py is in juju-0.7 0.7-0ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import os
import yaml
from juju.charm.errors import MetaDataError
from juju.errors import FileNotFound
from juju.lib import serializer
from juju.lib.format import is_valid_charm_format
from juju.lib.schema import (
SchemaError, Bool, Constant, Dict, Int,
KeyDict, OneOf, UnicodeOrString)
log = logging.getLogger("juju.charm")
UTF8_SCHEMA = UnicodeOrString("utf-8")
SCOPE_GLOBAL = "global"
SCOPE_CONTAINER = "container"
INTERFACE_SCHEMA = KeyDict({
"interface": UTF8_SCHEMA,
"limit": OneOf(Constant(None), Int()),
"scope": OneOf(Constant(SCOPE_GLOBAL), Constant(SCOPE_CONTAINER)),
"optional": Bool()},
optional=["scope"])
class InterfaceExpander(object):
"""Schema coercer that expands the interface shorthand notation.
We need this class because our charm shorthand is difficult to
work with (unfortunately). So we coerce shorthand and then store
the desired format in ZK.
Supports the following variants::
provides:
server: riak
admin: http
foobar:
interface: blah
provides:
server:
interface: mysql
limit:
optional: false
In all input cases, the output is the fully specified interface
representation as seen in the mysql interface description above.
"""
def __init__(self, limit):
"""Create relation interface reshaper.
@limit: the limit for this relation. Used to provide defaults
for a given kind of relation role (peer, provider, consumer)
"""
self.limit = limit
def coerce(self, value, path):
"""Coerce `value` into an expanded interface.
Helper method to support each of the variants, either the
charm does not specify limit and optional, such as foobar in
the above example; or the interface spec is just a string,
such as the ``server: riak`` example.
"""
if not isinstance(value, dict):
return {
"interface": UTF8_SCHEMA.coerce(value, path),
"limit": self.limit,
"scope": SCOPE_GLOBAL,
"optional": False}
else:
# Optional values are context-sensitive and/or have
# defaults, which is different than what KeyDict can
# readily support. So just do it here first, then
# coerce.
if "limit" not in value:
value["limit"] = self.limit
if "optional" not in value:
value["optional"] = False
value["scope"] = value.get("scope", SCOPE_GLOBAL)
return INTERFACE_SCHEMA.coerce(value, path)
SCHEMA = KeyDict({
"name": UTF8_SCHEMA,
"revision": Int(),
"summary": UTF8_SCHEMA,
"description": UTF8_SCHEMA,
"format": Int(),
"peers": Dict(UTF8_SCHEMA, InterfaceExpander(limit=1)),
"provides": Dict(UTF8_SCHEMA, InterfaceExpander(limit=None)),
"requires": Dict(UTF8_SCHEMA, InterfaceExpander(limit=1)),
"subordinate": Bool(),
}, optional=set(
["format", "provides", "requires", "peers", "revision",
"subordinate"]))
class MetaData(object):
"""Represents the charm info file.
The main metadata for a charm (name, revision, etc) is maintained
in the charm's info file. This class is able to parse,
validate, and provide access to data in the info file.
"""
def __init__(self, path=None):
self._data = {}
if path is not None:
self.load(path)
@property
def name(self):
"""The charm name."""
return self._data.get("name")
@property
def obsolete_revision(self):
"""The charm revision.
The charm revision acts as a version, but unlike e.g. package
versions, the charm revision is a monotonically increasing
integer. This should not be stored in metadata any more, but remains
for backward compatibility's sake.
"""
return self._data.get("revision")
@property
def summary(self):
"""The charm summary."""
return self._data.get("summary")
@property
def description(self):
"""The charm description."""
return self._data.get("description")
@property
def format(self):
"""Optional charm format, defaults to 1"""
return self._data.get("format", 1)
@property
def provides(self):
"""The charm provides relations."""
return self._data.get("provides")
@property
def requires(self):
"""The charm requires relations."""
return self._data.get("requires")
@property
def peers(self):
"""The charm peers relations."""
return self._data.get("peers")
@property
def is_subordinate(self):
"""Indicates the charm requires a contained relationship.
This property will effect the deployment options of its
charm. When a charm is_subordinate it can only be deployed
when its contained relationship is satisfied. See the
subordinates specification.
"""
return self._data.get("subordinate", False)
def get_serialization_data(self):
"""Get internal dictionary representing the state of this instance.
This is useful to embed this information inside other storage-related
dictionaries.
"""
return dict(self._data)
def load(self, path):
"""Load and parse the info file.
@param path: Path of the file to load.
Internally, this function will pass the content of the file to
the C{parse()} method.
"""
if not os.path.isfile(path):
raise FileNotFound(path)
with open(path) as f:
self.parse(f.read(), path)
def parse(self, content, path=None):
"""Parse the info file described by the given content.
@param content: Content of the info file to parse.
@param path: Optional path of the loaded file. Used when raising
errors.
@raise MetaDataError: When errors are found in the info data.
"""
try:
self.parse_serialization_data(
serializer.yaml_load(content), path)
except yaml.MarkedYAMLError, e:
# Capture the path name on the error if present.
if path is not None:
e.problem_mark = serializer.yaml_mark_with_path(
path, e.problem_mark)
raise
if "revision" in self._data and path:
log.warning(
"%s: revision field is obsolete. Move it to the 'revision' "
"file." % path)
if self.provides:
for rel in self.provides:
if rel.startswith("juju-"):
raise MetaDataError(
"Charm %s attempting to provide relation in "
"implicit relation namespace: %s" %
(self.name, rel))
interface = self.provides[rel]["interface"]
if interface.startswith("juju-"):
raise MetaDataError(
"Charm %s attempting to provide interface in implicit namespace: "
"%s (relation: %s)" % (self.name, interface, rel))
if self.is_subordinate:
proper_subordinate = False
if self.requires:
for relation_data in self.requires.values():
if relation_data.get("scope") == SCOPE_CONTAINER:
proper_subordinate = True
if not proper_subordinate:
raise MetaDataError(
"%s labeled subordinate but lacking scope:container `requires` relation" %
path)
if not is_valid_charm_format(self.format):
raise MetaDataError("Charm %s uses an unknown format: %s" % (
self.name, self.format))
def parse_serialization_data(self, serialization_data, path=None):
"""Parse the unprocessed serialization data and load in this instance.
@param serialization_data: Unprocessed data matching the
metadata schema.
@param path: Optional path of the loaded file. Used when
raising errors.
@raise MetaDataError: When errors are found in the info data.
"""
try:
self._data = SCHEMA.coerce(serialization_data, [])
except SchemaError, error:
if path:
path_info = " %s:" % path
else:
path_info = ""
raise MetaDataError("Bad data in charm info:%s %s" %
(path_info, error))
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