from __future__ import print_function, division, absolute_import import ast import os import sys import threading try: import yaml except ImportError: yaml = None from .compatibility import makedirs, builtins, Mapping, string_types no_default = '__no_default__' paths = [ os.getenv('DASK_ROOT_CONFIG', '/etc/dask'), os.path.join(sys.prefix, 'etc', 'dask'), os.path.join(os.path.expanduser('~'), '.config', 'dask'), os.path.join(os.path.expanduser('~'), '.dask') ] if 'DASK_CONFIG' in os.environ: PATH = os.environ['DASK_CONFIG'] paths.append(PATH) else: PATH = os.path.join(os.path.expanduser('~'), '.config', 'dask') global_config = config = {} config_lock = threading.Lock() defaults = [] def update(old, new, priority='new'): """ Update a nested dictionary with values from another This is like dict.update except that it smoothly merges nested values This operates in-place and modifies old Parameters ---------- priority: string {'old', 'new'} If new (default) then the new dictionary has preference. Otherwise the old dictionary does. Examples -------- >>> a = {'x': 1, 'y': {'a': 2}} >>> b = {'x': 2, 'y': {'b': 3}} >>> update(a, b) # doctest: +SKIP {'x': 2, 'y': {'a': 2, 'b': 3}} >>> a = {'x': 1, 'y': {'a': 2}} >>> b = {'x': 2, 'y': {'b': 3}} >>> update(a, b, priority='old') # doctest: +SKIP {'x': 1, 'y': {'a': 2, 'b': 3}} See Also -------- dask.config.merge """ for k, v in new.items(): if k not in old and isinstance(v, Mapping): old[k] = {} if isinstance(v, Mapping): if old[k] is None: old[k] = {} update(old[k], v, priority=priority) else: if priority == 'new' or k not in old: old[k] = v return old def merge(*dicts): """ Update a sequence of nested dictionaries This prefers the values in the latter dictionaries to those in the former Examples -------- >>> a = {'x': 1, 'y': {'a': 2}} >>> b = {'y': {'b': 3}} >>> merge(a, b) # doctest: +SKIP {'x': 1, 'y': {'a': 2, 'b': 3}} See Also -------- dask.config.update """ result = {} for d in dicts: update(result, d) return result def normalize_key(key): """ Replaces underscores with hyphens in string keys Parameters ---------- key : string, int, or float Key to assign. """ if isinstance(key, string_types): key = key.replace('_', '-') return key def normalize_nested_keys(config): """ Replaces underscores with hyphens for keys for a nested Mapping Examples -------- >>> a = {'x': 1, 'y_1': {'a_2': 2}} >>> normalize_nested_keys(a) {'x': 1, 'y-1': {'a-2': 2}} """ config_norm = {} for key, value in config.items(): if isinstance(value, Mapping): value = normalize_nested_keys(value) key_norm = normalize_key(key) config_norm[key_norm] = value return config_norm def collect_yaml(paths=paths): """ Collect configuration from yaml files This searches through a list of paths, expands to find all yaml or json files, and then parses each file. """ # Find all paths file_paths = [] for path in paths: if os.path.exists(path): if os.path.isdir(path): try: file_paths.extend(sorted([ os.path.join(path, p) for p in os.listdir(path) if os.path.splitext(p)[1].lower() in ('.json', '.yaml', '.yml') ])) except OSError: # Ignore permission errors pass else: file_paths.append(path) configs = [] # Parse yaml files for path in file_paths: try: with open(path) as f: data = yaml.load(f.read()) or {} data = normalize_nested_keys(data) configs.append(data) except (OSError, IOError): # Ignore permission errors pass return configs def collect_env(env=None): """ Collect config from environment variables This grabs environment variables of the form "DASK_FOO__BAR_BAZ=123" and turns these into config variables of the form ``{"foo": {"bar-baz": 123}}`` It transforms the key and value in the following way: - Lower-cases the key text - Treats ``__`` (double-underscore) as nested access - Replaces ``_`` (underscore) with a hyphen. - Calls ``ast.literal_eval`` on the value """ if env is None: env = os.environ d = {} for name, value in env.items(): if name.startswith('DASK_'): varname = name[5:].lower().replace('__', '.') varname = normalize_key(varname) try: d[varname] = ast.literal_eval(value) except (SyntaxError, ValueError): d[varname] = value result = {} set(d, config=result) return result def ensure_file( source, destination=None, comment=True): """ Copy file to default location if it does not already exist This tries to move a default configuration file to a default location if if does not already exist. It also comments out that file by default. This is to be used by downstream modules (like dask.distributed) that may have default configuration files that they wish to include in the default configuration path. Parameters ---------- source : string, filename Source configuration file, typically within a source directory. destination : string, directory Destination directory. Configurable by ``DASK_CONFIG`` environment variable, falling back to ~/.config/dask. comment : bool, True by default Whether or not to comment out the config file when copying. """ if destination is None: destination = PATH # destination is a file and already exists, never overwrite if os.path.isfile(destination): return # If destination is not an existing file, interpret as a directory, # use the source basename as the filename directory = destination destination = os.path.join(directory, os.path.basename(source)) try: if not os.path.exists(destination): makedirs(directory, exist_ok=True) # Atomically create destination. Parallel testing discovered # a race condition where a process can be busy creating the # destination while another process reads an empty config file. tmp = '%s.tmp.%d' % (destination, os.getpid()) with open(source) as f: lines = list(f) if comment: lines = ['# ' + line if line.strip() and not line.startswith('#') else line for line in lines] with open(tmp, 'w') as f: f.write(''.join(lines)) try: os.rename(tmp, destination) except OSError: os.remove(tmp) except OSError: pass class set(object): """ Temporarily set configuration values within a context manager Examples -------- >>> import dask >>> with dask.config.set({'foo': 123}): ... pass See Also -------- dask.config.get """ def __init__(self, arg=None, config=config, lock=config_lock, **kwargs): if arg and not kwargs: kwargs = arg with lock: self.config = config self.old = {} for key, value in kwargs.items(): self._assign(key.split('.'), value, config, old=self.old) def __enter__(self): return self.config def __exit__(self, type, value, traceback): for keys, value in self.old.items(): if value == '--delete--': d = self.config try: while len(keys) > 1: d = d[keys[0]] keys = keys[1:] del d[keys[0]] except KeyError: pass else: self._assign(keys, value, self.config) @classmethod def _assign(cls, keys, value, d, old=None, path=[]): """ Assign value into a nested configuration dictionary Optionally record the old values in old Parameters ---------- keys: Sequence[str] The nested path of keys to assign the value, similar to toolz.put_in value: object d: dict The part of the nested dictionary into which we want to assign the value old: dict, optional If provided this will hold the old values path: List[str] Used internally to hold the path of old values """ key = normalize_key(keys[0]) if len(keys) == 1: if old is not None: path_key = tuple(path + [key]) if key in d: old[path_key] = d[key] else: old[path_key] = '--delete--' d[key] = value else: if key not in d: d[key] = {} if old is not None: old[tuple(path + [key])] = '--delete--' old = None cls._assign(keys[1:], value, d[key], path=path + [key], old=old) def collect(paths=paths, env=None): """ Collect configuration from paths and environment variables Parameters ---------- paths : List[str] A list of paths to search for yaml config files env : dict The system environment variables Returns ------- config: dict See Also -------- dask.config.refresh: collect configuration and update into primary config """ if env is None: env = os.environ configs = [] if yaml: configs.extend(collect_yaml(paths=paths)) configs.append(collect_env(env=env)) return merge(*configs) def refresh(config=config, defaults=defaults, **kwargs): """ Update configuration by re-reading yaml files and env variables This mutates the global dask.config.config, or the config parameter if passed in. This goes through the following stages: 1. Clearing out all old configuration 2. Updating from the stored defaults from downstream libraries (see update_defaults) 3. Updating from yaml files and environment variables Note that some functionality only checks configuration once at startup and may not change behavior, even if configuration changes. It is recommended to restart your python process if convenient to ensure that new configuration changes take place. See Also -------- dask.config.collect: for parameters dask.config.update_defaults """ config.clear() for d in defaults: update(config, d, priority='old') update(config, collect(**kwargs)) def get(key, default=no_default, config=config): """ Get elements from global config Use '.' for nested access Examples -------- >>> from dask import config >>> config.get('foo') # doctest: +SKIP {'x': 1, 'y': 2} >>> config.get('foo.x') # doctest: +SKIP 1 >>> config.get('foo.x.y', default=123) # doctest: +SKIP 123 See Also -------- dask.config.set """ keys = key.split('.') result = config for k in keys: k = normalize_key(k) try: result = result[k] except (TypeError, IndexError, KeyError): if default is not no_default: return default else: raise return result def rename(aliases, config=config): """ Rename old keys to new keys This helps migrate older configuration versions over time """ old = list() new = dict() for o, n in aliases.items(): value = get(o, None, config=config) if value is not None: old.append(o) new[n] = value for k in old: del config[k] # TODO: support nested keys set(new, config=config) def update_defaults(new, config=config, defaults=defaults): """ Add a new set of defaults to the configuration It does two things: 1. Add the defaults to a global collection to be used by refresh later 2. Updates the global config with the new configuration prioritizing older values over newer ones """ defaults.append(new) update(config, new, priority='old') def expand_environment_variables(config): ''' Expand environment variables in a nested config dictionary This function will recursively search through any nested dictionaries and/or lists. Parameters ---------- config : dict, iterable, or str Input object to search for environment variables Returns ------- config : same type as input Examples -------- >>> expand_environment_variables({'x': [1, 2, '$USER']}) # doctest: +SKIP {'x': [1, 2, 'my-username']} ''' if isinstance(config, Mapping): return {k: expand_environment_variables(v) for k, v in config.items()} elif isinstance(config, str): return os.path.expandvars(config) elif isinstance(config, (list, tuple, builtins.set)): return type(config)([expand_environment_variables(v) for v in config]) else: return config refresh()