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# Copyright 2020 Canonical Ltd.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Infrastructure for the opslib functionality."""
import logging
import os
import re
import sys
from ast import literal_eval
from importlib.util import module_from_spec
from importlib.machinery import ModuleSpec
from pkgutil import get_importer
from types import ModuleType
from typing import List
__all__ = ('use', 'autoimport')
logger = logging.getLogger(__name__)
_libraries = None
_libline_re = re.compile(r'''^LIB([A-Z]+)\s*=\s*([0-9]+|['"][a-zA-Z0-9_.\-@]+['"])''')
_libname_re = re.compile(r'''^[a-z][a-z0-9]+$''')
# Not perfect, but should do for now.
_libauthor_re = re.compile(r'''^[A-Za-z0-9_+.-]+@[a-z0-9_-]+(?:\.[a-z0-9_-]+)*\.[a-z]{2,3}$''')
def use(name: str, api: int, author: str) -> ModuleType:
"""Use a library from the ops libraries.
Args:
name: the name of the library requested.
api: the API version of the library.
author: the author of the library. If not given, requests the
one in the standard library.
Raises:
ImportError: if the library cannot be found.
TypeError: if the name, api, or author are the wrong type.
ValueError: if the name, api, or author are invalid.
"""
if not isinstance(name, str):
raise TypeError("invalid library name: {!r} (must be a str)".format(name))
if not isinstance(author, str):
raise TypeError("invalid library author: {!r} (must be a str)".format(author))
if not isinstance(api, int):
raise TypeError("invalid library API: {!r} (must be an int)".format(api))
if api < 0:
raise ValueError('invalid library api: {} (must be ≥0)'.format(api))
if not _libname_re.match(name):
raise ValueError("invalid library name: {!r} (chars and digits only)".format(name))
if not _libauthor_re.match(author):
raise ValueError("invalid library author email: {!r}".format(author))
if _libraries is None:
autoimport()
versions = _libraries.get((name, author), ())
for lib in versions:
if lib.api == api:
return lib.import_module()
others = ', '.join(str(lib.api) for lib in versions)
if others:
msg = 'cannot find "{}" from "{}" with API version {} (have {})'.format(
name, author, api, others)
else:
msg = 'cannot find library "{}" from "{}"'.format(name, author)
raise ImportError(msg, name=name)
def autoimport():
"""Find all libs in the path and enable use of them.
You only need to call this if you've installed a package or
otherwise changed sys.path in the current run, and need to see the
changes. Otherwise libraries are found on first call of `use`.
"""
global _libraries
_libraries = {}
for spec in _find_all_specs(sys.path):
lib = _parse_lib(spec)
if lib is None:
continue
versions = _libraries.setdefault((lib.name, lib.author), [])
versions.append(lib)
versions.sort(reverse=True)
def _find_all_specs(path):
for sys_dir in path:
if sys_dir == "":
sys_dir = "."
try:
top_dirs = os.listdir(sys_dir)
except (FileNotFoundError, NotADirectoryError):
continue
except OSError as e:
logger.debug("Tried to look for ops.lib packages under '%s': %s", sys_dir, e)
continue
logger.debug("Looking for ops.lib packages under '%s'", sys_dir)
for top_dir in top_dirs:
opslib = os.path.join(sys_dir, top_dir, 'opslib')
try:
lib_dirs = os.listdir(opslib)
except (FileNotFoundError, NotADirectoryError):
continue
except OSError as e:
logger.debug(" Tried '%s': %s", opslib, e) # *lots* of things checked here
continue
else:
logger.debug(" Trying '%s'", opslib)
finder = get_importer(opslib)
if finder is None:
logger.debug(" Finder for '%s' is None", opslib)
continue
if not hasattr(finder, 'find_spec'):
logger.debug(" Finder for '%s' has no find_spec", opslib)
continue
for lib_dir in lib_dirs:
spec_name = "{}.opslib.{}".format(top_dir, lib_dir)
spec = finder.find_spec(spec_name)
if spec is None:
logger.debug(" No spec for %r", spec_name)
continue
if spec.loader is None:
# a namespace package; not supported
logger.debug(" No loader for %r (probably a namespace package)", spec_name)
continue
logger.debug(" Found %r", spec_name)
yield spec
# only the first this many lines of a file are looked at for the LIB* constants
_MAX_LIB_LINES = 99
# these keys, with these types, are needed to have an opslib
_NEEDED_KEYS = {'NAME': str, 'AUTHOR': str, 'API': int, 'PATCH': int}
def _join_and(keys: List[str]) -> str:
if len(keys) == 0:
return ""
if len(keys) == 1:
return keys[0]
return ", ".join(keys[:-1]) + ", and " + keys[-1]
class _Missing:
"""Helper to get the difference between what was found and what was needed when logging."""
def __init__(self, found):
self._found = found
def __str__(self):
exp = set(_NEEDED_KEYS)
got = set(self._found)
if len(got) == 0:
return "missing {}".format(_join_and(sorted(exp)))
return "got {}, but missing {}".format(
_join_and(sorted(got)),
_join_and(sorted(exp - got)))
def _parse_lib(spec):
if spec.origin is None:
# "can't happen"
logger.warning("No origin for %r (no idea why; please report)", spec.name)
return None
logger.debug(" Parsing %r", spec.name)
try:
with open(spec.origin, 'rt', encoding='utf-8') as f:
libinfo = {}
for n, line in enumerate(f):
if len(libinfo) == len(_NEEDED_KEYS):
break
if n > _MAX_LIB_LINES:
logger.debug(
" Missing opslib metadata after reading to line %d: %s",
_MAX_LIB_LINES, _Missing(libinfo))
return None
m = _libline_re.match(line)
if m is None:
continue
key, value = m.groups()
if key in _NEEDED_KEYS:
value = literal_eval(value)
if not isinstance(value, _NEEDED_KEYS[key]):
logger.debug(
" Bad type for %s: expected %s, got %s",
key, _NEEDED_KEYS[key].__name__, type(value).__name__)
return None
libinfo[key] = value
else:
if len(libinfo) != len(_NEEDED_KEYS):
logger.debug(
" Missing opslib metadata after reading to end of file: %s",
_Missing(libinfo))
return None
except Exception as e:
logger.debug(" Failed: %s", e)
return None
lib = _Lib(spec, libinfo['NAME'], libinfo['AUTHOR'], libinfo['API'], libinfo['PATCH'])
logger.debug(" Success: found library %s", lib)
return lib
class _Lib:
def __init__(self, spec: ModuleSpec, name: str, author: str, api: int, patch: int):
self.spec = spec
self.name = name
self.author = author
self.api = api
self.patch = patch
self._module = None
def __repr__(self):
return "<_Lib {}>".format(self)
def __str__(self):
return "{0.name} by {0.author}, API {0.api}, patch {0.patch}".format(self)
def import_module(self) -> ModuleType:
if self._module is None:
module = module_from_spec(self.spec)
self.spec.loader.exec_module(module)
self._module = module
return self._module
def __eq__(self, other):
if not isinstance(other, _Lib):
return NotImplemented
a = (self.name, self.author, self.api, self.patch)
b = (other.name, other.author, other.api, other.patch)
return a == b
def __lt__(self, other):
if not isinstance(other, _Lib):
return NotImplemented
a = (self.name, self.author, self.api, self.patch)
b = (other.name, other.author, other.api, other.patch)
return a < b