add authentication

config.py

@@ -0,0 +1,109 @@
+"""
+Application configuration
+
+values can be configured in the OS environment via KEY_NAME=...
+or in a toml file using 
+
+[section]
+foo = ...
+bar_baz = ...
+
+in the latter case, the section and name are uppercased and joined with `_`,
+then inserted into the OS environment (in this case, resulting in 
+SECTION_FOO=... and SECTION_BAR_BAZ=... ). 
+The OS environment takes precedence - if a key is found in both env and config,
+the config setting will be ignored.
+"""
+import tomllib
+import logging
+from os import environ
+from functools import wraps
+
+import consts
+
+logger = logging.getLogger(consts.LOG_ROOT)
+
+
+def load(file):
+    """
+    Load configuration from toml and add to environment
+    """
+
+    if file is None:
+        logger.debug('no config file provided.')
+    else:
+        logger.debug('loading config')
+        with open(file, 'rb') as fh:
+            config = tomllib.load(fh)
+            for k, v in config.items():
+                for k_inner, v_inner in v.items():
+                    effective_key = f'{k.upper()}_{k_inner.upper()}'
+                    if effective_key in environ:
+                        logger.warning(
+                            '%s already exists in os environment, skipping', effective_key)
+                    else:
+                        environ[effective_key] = str(v_inner)
+                    logger.debug('raw: %s = %s', effective_key,
+                                 environ[effective_key])
+
+
+def env(key, default=None):
+    """
+    retrieve a key from the OS environment.
+    throws `KeyError` when the key is not found and no default fallback is provided.
+    """
+    if default is None:
+        return environ[key]
+    return environ.get(key, default=default)
+
+
+def logged(f):
+    """
+    logging wrapper for resolved configuration settings
+    """
+    @wraps(f)
+    def decorated(*args, **kwargs):
+        res = f(*args, **kwargs)
+        logger.debug('resolved: %s = %s', args[0], res)
+        return res
+    return decorated
+
+
+@logged
+def int_val(key, default=None):
+    """
+    retrieve configuration value as int
+    """
+
+    return int(env(key, default=default))
+
+
+def strtobool(val):
+    """Convert a string representation of truth to true (1) or false (0).
+    True values are 'y', 'yes', 't', 'true', 'on', and '1'; false values
+    are 'n', 'no', 'f', 'false', 'off', and '0'.  Raises ValueError if
+    'val' is anything else.
+    """
+    val = val.lower()
+    if val in ("y", "yes", "t", "true", "on", "1"):
+        return True
+    elif val in ("n", "no", "f", "false", "off", "0"):
+        return False
+    else:
+        raise ValueError(f'Invalid bool string: {val}')
+
+
+@logged
+def bool_val(key, default=None):
+    """
+    retrieve configuration value as bool
+    """
+    return strtobool(env(key, default=default))
+
+
+@logged
+def str_val(key, default=None):
+    """
+    retrieve configuration value as bool
+    """
+    return env(key, default=default)