substitute_vars | SignalWire

Recursively substitute environment variables in a configuration value. Supports ${VAR} and ${VAR|default} syntax.

Parameters

value

AnyRequired

The value to process. Can be a string, dict, list, or any other type. Strings are scanned for ${VAR|default} patterns. Dicts and lists are processed recursively.

max_depth

intDefaults to 10

Maximum recursion depth to prevent infinite substitution loops.

Returns

Any — The value with all ${VAR|default} patterns replaced by the corresponding environment variable values. Strings that resolve to "true"/"false" are converted to booleans. Numeric strings are converted to int or float.

Example

1 import os
2 from signalwire.core.config_loader import ConfigLoader
3 
4 os.environ["API_KEY"] = "secret123"
5 loader = ConfigLoader()
6 
7 # Simple substitution
8 result = loader.substitute_vars("${API_KEY}")
9 print(result)  # "secret123"
10 
11 # With default value
12 result = loader.substitute_vars("${MISSING_VAR|fallback}")
13 print(result)  # "fallback"
14 
15 # Nested structure
16 config = {
17     "auth": {"token": "${API_KEY}"},
18     "timeout": "${TIMEOUT|30}",
19 }
20 result = loader.substitute_vars(config)
21 print(result)  # {"auth": {"token": "secret123"}, "timeout": 30}