mergeWithEnv

Merge the loaded configuration with environment variables whose names start with a given prefix. Config file values take precedence over environment variables — env vars only fill in keys that are missing from the config.

Matching env var names are:

1. Stripped of the prefix
2. Lowercased
3. Split on _ to produce a nested object path

For example, with prefix SWML_, SWML_SERVER_PORT=3000 produces { server: { port: "3000" } }.

Parameters

Returns

Record<string, unknown> — the merged configuration (file + prefixed env vars) with ${VAR} substitution applied to file values.

Example

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import { ConfigLoader } from '@signalwire/sdk';
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// Given config.json: { "server": { "host": "0.0.0.0" } }
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// And env: SWML_SERVER_PORT=3000
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const loader = new ConfigLoader('config.json');
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const merged = loader.mergeWithEnv();
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console.log(merged);
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// { server: { host: "0.0.0.0", port: "3000" } }