65 lines
1.9 KiB
Python
65 lines
1.9 KiB
Python
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"""Typed reading of the container's environment.
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Everything in the environment is text, including values the client later
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compares as numbers or passes to seaf-cli. Reading them directly leaves two
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failures that are silent until much later: an unset variable becomes None and
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reaches seaf-cli as the string "None", and a numeric setting stays a string
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that never equals the integer it is compared against.
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"""
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import os
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from dsc.errors import ConfigError
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_TRUE_VALUES = {"true", "1", "yes", "on"}
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_FALSE_VALUES = {"false", "0", "no", "off"}
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def env_str(name: str, default: str = None) -> str:
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"""Return a text setting. An empty variable counts as unset."""
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value = os.getenv(name)
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if value is None or value == "":
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return default
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return value
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def env_int(name: str, default: int, minimum: int = 0) -> int:
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"""
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Return a numeric setting as an int, never as text and never as None.
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Values below ``minimum`` are rejected: a negative speed limit or deletion
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threshold is not something to pass on to seaf-cli and hope for the best.
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"""
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raw = env_str(name)
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if raw is None:
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return default
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stripped = raw.strip()
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try:
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value = int(stripped, 10)
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except ValueError:
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raise ConfigError(
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f"{name} must be a whole number, got {stripped!r}"
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)
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if value < minimum:
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raise ConfigError(
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f"{name} must be {minimum} or greater, got {stripped!r}"
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)
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return value
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def env_bool(name: str, default: bool = False) -> bool:
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"""Return a boolean setting, accepting the usual spellings."""
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raw = env_str(name)
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if raw is None:
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return default
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value = raw.strip().lower()
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if value in _TRUE_VALUES:
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return True
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if value in _FALSE_VALUES:
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return False
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accepted = ", ".join(sorted(_TRUE_VALUES | _FALSE_VALUES))
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raise ConfigError(f"{name} must be one of {accepted}, got {raw.strip()!r}")
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