+"""Constants used in CSIT.
+
+Here, "constant" means a value that keeps its value since initialization.
+However, the value does not need to be hardcoded here,
+some values are affected by environment variables.
+
+TODO: Review env and constant names, make them matching if possible.
+"""
+
+
+import os
+
+
+def get_str_from_env(env_var_names, default_value):
+ """Attempt to read string from environment variable, return that or default.
+
+ If environment variable exists, but is empty (and default is not),
+ empty string is returned.
+
+ Several environment variable names are examined, as CSIT currently supports
+ a mix of naming convensions.
+ Here "several" means there are hardcoded prefixes to try,
+ and env_var_names itself can be single name, or a list or a tuple of names.
+
+ :param env_var_names: Base names of environment variable to attempt to read.
+ :param default_value: Value to return if the env var does not exist.
+ :type env_var_names: str, or list of str, or tuple of str
+ :type default_value: str
+ :returns: The value read, or default value.
+ :rtype: str
+ """
+ prefixes = ("FDIO_CSIT_", "CSIT_", "")
+ if not isinstance(env_var_names, (list, tuple)):
+ env_var_names = [env_var_names]
+ for name in env_var_names:
+ for prefix in prefixes:
+ value = os.environ.get(prefix + name, None)
+ if value is not None:
+ return value
+ return default_value
+
+
+def get_int_from_env(env_var_names, default_value):
+ """Attempt to read int from environment variable, return that or default.
+
+ String value is read, default is returned also if conversion fails.
+
+ :param env_var_names: Base names of environment variable to attempt to read.
+ :param default_value: Value to return if read or conversion fails.
+ :type env_var_names: str, or list of str, or tuple of str
+ :type default_value: int
+ :returns: The value read, or default value.
+ :rtype: int
+ """
+ env_str = get_str_from_env(env_var_names, "")
+ try:
+ return int(env_str)
+ except ValueError:
+ return default_value
+
+
+def get_float_from_env(env_var_names, default_value):
+ """Attempt to read float from environment variable, return that or default.
+
+ String value is read, default is returned also if conversion fails.
+
+ :param env_var_names: Base names of environment variable to attempt to read.
+ :param default_value: Value to return if read or conversion fails.
+ :type env_var_names: str, or list of str, or tuple of str
+ :type default_value: float
+ :returns: The value read, or default value.
+ :rtype: float
+ """
+ env_str = get_str_from_env(env_var_names, "")
+ try:
+ return float(env_str)
+ except ValueError:
+ return default_value
+
+
+def get_pessimistic_bool_from_env(env_var_names):
+ """Attempt to read bool from environment variable, assume False by default.
+
+ Conversion is lenient and pessimistic, only few strings are considered true.
+
+ :param env_var_names: Base names of environment variable to attempt to read.
+ :type env_var_names: str, or list of str, or tuple of str
+ :returns: The value read, or False.
+ :rtype: bool
+ """
+ env_str = get_str_from_env(env_var_names, "").lower()
+ return True if env_str in ("true", "yes", "y", "1") else False
+
+
+def get_optimistic_bool_from_env(env_var_names):
+ """Attempt to read bool from environment variable, assume True by default.
+
+ Conversion is lenient and optimistic, only few strings are considered false.
+
+ :param env_var_names: Base names of environment variable to attempt to read.
+ :type env_var_names: str, or list of str, or tuple of str
+ :returns: The value read, or True.
+ :rtype: bool
+ """
+ env_str = get_str_from_env(env_var_names, "").lower()
+ return False if env_str in ("false", "no", "n", "0") else True
Code Review / csit.git / commitdiff