Module refinery.lib.environment

A common interface to all binary refinery configuration settings available via environment variables. This module is also host to the logging configuration.

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
A common interface to all binary refinery configuration settings available via environment
variables. This module is also host to the logging configuration.
"""
from __future__ import annotations

import os
import logging

from enum import IntEnum
from typing import Optional, TypeVar, Generic

_T = TypeVar('_T')

Logger = logging.Logger


class LogLevel(IntEnum):
    """
    An enumeration representing the current log level:
    """
    DETACHED = logging.CRITICAL + 100
    """
    This unit is not attached to a terminal but has been instantiated in
    code. This means that the only way to communicate problems is to throw
    an exception.
    """
    NONE = logging.CRITICAL + 50

    @classmethod
    def FromVerbosity(cls, verbosity: int):
        if verbosity < 0:
            return cls.DETACHED
        return {
            0: cls.WARNING,
            1: cls.INFO,
            2: cls.DEBUG
        }.get(verbosity, cls.DEBUG)

    NOTSET   = logging.NOTSET    # noqa
    CRITICAL = logging.CRITICAL  # noqa
    FATAL    = logging.FATAL     # noqa
    ERROR    = logging.ERROR     # noqa
    WARNING  = logging.WARNING   # noqa
    WARN     = logging.WARN      # noqa
    INFO     = logging.INFO      # noqa
    DEBUG    = logging.DEBUG     # noqa

    @property
    def verbosity(self) -> int:
        if self.value >= LogLevel.DETACHED:
            return -1
        if self.value >= LogLevel.WARNING:
            return +0
        if self.value >= LogLevel.INFO:
            return +1
        if self.value >= LogLevel.DEBUG:
            return +2
        else:
            return -1


class RefineryFormatter(logging.Formatter):
    """
    The binary refinery log formatter class.
    """

    NAMES = {
        logging.CRITICAL : 'failure',
        logging.ERROR    : 'failure',
        logging.WARNING  : 'warning',
        logging.INFO     : 'comment',
        logging.DEBUG    : 'verbose',
    }

    def __init__(self, format, **kwargs):
        super().__init__(format, **kwargs)

    def formatMessage(self, record: logging.LogRecord) -> str:
        record.custom_level_name = self.NAMES[record.levelno]
        return super().formatMessage(record)


def logger(name: str) -> logging.Logger:
    """
    Obtain a logger which is configured with the default refinery format.
    """
    logger = logging.getLogger(name)
    if not logger.hasHandlers():
        stream = logging.StreamHandler()
        stream.setFormatter(RefineryFormatter(
            '({asctime}) {custom_level_name} in {name}: {message}',
            style='{',
            datefmt='%H:%M:%S',
        ))
        logger.addHandler(stream)
    logger.propagate = False
    return logger


class EnvironmentVariableSetting(Generic[_T]):
    """
    Abstraction of an environment variable based setting.
    """
    key: str
    value: Optional[_T]

    def __init__(self, name: str):
        self.key = F'REFINERY_{name}'
        self.value = self.read()

    def read(self) -> _T:
        return None


class EVBool(EnvironmentVariableSetting[bool]):
    """
    Boolean setting stored in an environment variable. Except for the strings `0`, `no`, `off`,
    and `false`, every value is interpreted as `True`. If the variable does not exist, the value
    is interpreted as `False`.
    """
    def read(self):
        value = os.environ.get(self.key, None)
        if value is None:
            return False
        else:
            value = value.lower().strip()
        if not value:
            return False
        if value.isdigit():
            return bool(int(value))
        return value not in {'no', 'off', 'false'}


class EVInt(EnvironmentVariableSetting[int]):
    """
    An integer value stored in an environment variable. The variable is interpreted as a Python
    integer literal. A non-existant variable is interpreted as zero.
    """
    def read(self):
        try:
            return int(os.environ[self.key], 0)
        except (KeyError, ValueError):
            return 0


class EVLog(EnvironmentVariableSetting[Optional[LogLevel]]):
    """
    A log level stored in an environment variable. This can be specified as either the name of the
    log level or its integer value.
    """
    def read(self):
        try:
            loglevel = os.environ[self.key]
        except KeyError:
            return None
        if loglevel.isdigit():
            return LogLevel.FromVerbosity(int(loglevel))
        try:
            loglevel = LogLevel[loglevel]
        except KeyError:
            levels = ', '.join(ll.name for ll in LogLevel)
            logger(__name__).warning(
                F'ignoring unknown verbosity "{loglevel!r}"; pick from: {levels}')
            return None
        else:
            return loglevel


class environment:
    """
    Provides access to refinery-related configuration in environment variables.
    """
    verbosity = EVLog('VERBOSITY')
    term_size = EVInt('TERM_SIZE')
    colorless = EVBool('COLORLESS')
    disable_size_format = EVBool('DISABLE_SIZE_FORMAT')
    silence_ps1_warning = EVBool('SILENCE_PS1_WARNING')
    disable_ps1_bandaid = EVBool('DISABLE_PS1_BANDAID')

Functions

def logger(name)

Obtain a logger which is configured with the default refinery format.

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def logger(name: str) -> logging.Logger:
    """
    Obtain a logger which is configured with the default refinery format.
    """
    logger = logging.getLogger(name)
    if not logger.hasHandlers():
        stream = logging.StreamHandler()
        stream.setFormatter(RefineryFormatter(
            '({asctime}) {custom_level_name} in {name}: {message}',
            style='{',
            datefmt='%H:%M:%S',
        ))
        logger.addHandler(stream)
    logger.propagate = False
    return logger

Classes

class LogLevel (value, names=None, *, module=None, qualname=None, type=None, start=1)

An enumeration representing the current log level:

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class LogLevel(IntEnum):
    """
    An enumeration representing the current log level:
    """
    DETACHED = logging.CRITICAL + 100
    """
    This unit is not attached to a terminal but has been instantiated in
    code. This means that the only way to communicate problems is to throw
    an exception.
    """
    NONE = logging.CRITICAL + 50

    @classmethod
    def FromVerbosity(cls, verbosity: int):
        if verbosity < 0:
            return cls.DETACHED
        return {
            0: cls.WARNING,
            1: cls.INFO,
            2: cls.DEBUG
        }.get(verbosity, cls.DEBUG)

    NOTSET   = logging.NOTSET    # noqa
    CRITICAL = logging.CRITICAL  # noqa
    FATAL    = logging.FATAL     # noqa
    ERROR    = logging.ERROR     # noqa
    WARNING  = logging.WARNING   # noqa
    WARN     = logging.WARN      # noqa
    INFO     = logging.INFO      # noqa
    DEBUG    = logging.DEBUG     # noqa

    @property
    def verbosity(self) -> int:
        if self.value >= LogLevel.DETACHED:
            return -1
        if self.value >= LogLevel.WARNING:
            return +0
        if self.value >= LogLevel.INFO:
            return +1
        if self.value >= LogLevel.DEBUG:
            return +2
        else:
            return -1

Ancestors

• enum.IntEnum
• builtins.int
• enum.Enum

Class variables

var DETACHED

This unit is not attached to a terminal but has been instantiated in code. This means that the only way to communicate problems is to throw an exception.

var NONE

var NOTSET

var CRITICAL

var FATAL

var ERROR

var WARNING

var WARN

var INFO

var DEBUG

Static methods

def FromVerbosity(verbosity)

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@classmethod
def FromVerbosity(cls, verbosity: int):
    if verbosity < 0:
        return cls.DETACHED
    return {
        0: cls.WARNING,
        1: cls.INFO,
        2: cls.DEBUG
    }.get(verbosity, cls.DEBUG)

Instance variables

var verbosity

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@property
def verbosity(self) -> int:
    if self.value >= LogLevel.DETACHED:
        return -1
    if self.value >= LogLevel.WARNING:
        return +0
    if self.value >= LogLevel.INFO:
        return +1
    if self.value >= LogLevel.DEBUG:
        return +2
    else:
        return -1

class RefineryFormatter (format, **kwargs)

The binary refinery log formatter class.

Initialize the formatter with specified format strings.

Initialize the formatter either with the specified format string, or a default as described above. Allow for specialized date formatting with the optional datefmt argument. If datefmt is omitted, you get an ISO8601-like (or RFC 3339-like) format.

Use a style parameter of '%', '{' or '$' to specify that you want to use one of %-formatting, :meth:str.format ({}) formatting or :class:string.Template formatting in your format string.

Changed in version: 3.2

Added the style parameter.

Expand source code Browse git

class RefineryFormatter(logging.Formatter):
    """
    The binary refinery log formatter class.
    """

    NAMES = {
        logging.CRITICAL : 'failure',
        logging.ERROR    : 'failure',
        logging.WARNING  : 'warning',
        logging.INFO     : 'comment',
        logging.DEBUG    : 'verbose',
    }

    def __init__(self, format, **kwargs):
        super().__init__(format, **kwargs)

    def formatMessage(self, record: logging.LogRecord) -> str:
        record.custom_level_name = self.NAMES[record.levelno]
        return super().formatMessage(record)

Ancestors

• logging.Formatter

Class variables

var NAMES

Methods

def formatMessage(self, record)

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def formatMessage(self, record: logging.LogRecord) -> str:
    record.custom_level_name = self.NAMES[record.levelno]
    return super().formatMessage(record)

class EnvironmentVariableSetting (name)

Abstraction of an environment variable based setting.

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class EnvironmentVariableSetting(Generic[_T]):
    """
    Abstraction of an environment variable based setting.
    """
    key: str
    value: Optional[_T]

    def __init__(self, name: str):
        self.key = F'REFINERY_{name}'
        self.value = self.read()

    def read(self) -> _T:
        return None

Ancestors

• typing.Generic

Subclasses

• EVBool
• EVInt
• EVLog

Class variables

var key

var value

Methods

def read(self)

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def read(self) -> _T:
    return None

class EVBool (name)

Boolean setting stored in an environment variable. Except for the strings 0, no, off, and false, every value is interpreted as True. If the variable does not exist, the value is interpreted as False.

Expand source code Browse git

class EVBool(EnvironmentVariableSetting[bool]):
    """
    Boolean setting stored in an environment variable. Except for the strings `0`, `no`, `off`,
    and `false`, every value is interpreted as `True`. If the variable does not exist, the value
    is interpreted as `False`.
    """
    def read(self):
        value = os.environ.get(self.key, None)
        if value is None:
            return False
        else:
            value = value.lower().strip()
        if not value:
            return False
        if value.isdigit():
            return bool(int(value))
        return value not in {'no', 'off', 'false'}

Ancestors

• EnvironmentVariableSetting
• typing.Generic

Class variables

var key

var value

Methods

def read(self)

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def read(self):
    value = os.environ.get(self.key, None)
    if value is None:
        return False
    else:
        value = value.lower().strip()
    if not value:
        return False
    if value.isdigit():
        return bool(int(value))
    return value not in {'no', 'off', 'false'}

class EVInt (name)

An integer value stored in an environment variable. The variable is interpreted as a Python integer literal. A non-existant variable is interpreted as zero.

Expand source code Browse git

class EVInt(EnvironmentVariableSetting[int]):
    """
    An integer value stored in an environment variable. The variable is interpreted as a Python
    integer literal. A non-existant variable is interpreted as zero.
    """
    def read(self):
        try:
            return int(os.environ[self.key], 0)
        except (KeyError, ValueError):
            return 0

Ancestors

• EnvironmentVariableSetting
• typing.Generic

Class variables

var key

var value

Methods

def read(self)

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def read(self):
    try:
        return int(os.environ[self.key], 0)
    except (KeyError, ValueError):
        return 0

class EVLog (name)

A log level stored in an environment variable. This can be specified as either the name of the log level or its integer value.

Expand source code Browse git

class EVLog(EnvironmentVariableSetting[Optional[LogLevel]]):
    """
    A log level stored in an environment variable. This can be specified as either the name of the
    log level or its integer value.
    """
    def read(self):
        try:
            loglevel = os.environ[self.key]
        except KeyError:
            return None
        if loglevel.isdigit():
            return LogLevel.FromVerbosity(int(loglevel))
        try:
            loglevel = LogLevel[loglevel]
        except KeyError:
            levels = ', '.join(ll.name for ll in LogLevel)
            logger(__name__).warning(
                F'ignoring unknown verbosity "{loglevel!r}"; pick from: {levels}')
            return None
        else:
            return loglevel

Ancestors

• EnvironmentVariableSetting
• typing.Generic

Class variables

var key

var value

Methods

def read(self)

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def read(self):
    try:
        loglevel = os.environ[self.key]
    except KeyError:
        return None
    if loglevel.isdigit():
        return LogLevel.FromVerbosity(int(loglevel))
    try:
        loglevel = LogLevel[loglevel]
    except KeyError:
        levels = ', '.join(ll.name for ll in LogLevel)
        logger(__name__).warning(
            F'ignoring unknown verbosity "{loglevel!r}"; pick from: {levels}')
        return None
    else:
        return loglevel

class environment

Provides access to refinery-related configuration in environment variables.

Expand source code Browse git

class environment:
    """
    Provides access to refinery-related configuration in environment variables.
    """
    verbosity = EVLog('VERBOSITY')
    term_size = EVInt('TERM_SIZE')
    colorless = EVBool('COLORLESS')
    disable_size_format = EVBool('DISABLE_SIZE_FORMAT')
    silence_ps1_warning = EVBool('SILENCE_PS1_WARNING')
    disable_ps1_bandaid = EVBool('DISABLE_PS1_BANDAID')

Class variables

var verbosity

var term_size

var colorless

var disable_size_format

var silence_ps1_warning

var disable_ps1_bandaid