configurable-handler.ts

type LambdaConfig = Record<string, string>;

type ConfigurableHandler = (config: LambdaConfig) => Promise<void>;

const buildLambdaHandler = (handler: ConfigurableHandler, prefix: string) => {
	Log.info(`Finding config for: ${prefix}`);
	// Include configuration logic to pull from env or wherever 
	const config: LambdaConfig = { 'foo/bar': 'baz' };

	return () => handler(config);
};

// When you want to build a lambda:

export const myLambdaHandler = async (
	config: LambdaConfig,
): Promise<void> => {
	Log.info(config);
	await Promise.resolve();
};

export const main = buildLambdaHandler(myLambdaHandler, 'myLambda');

if (require.main === module) {
	void (async () => await main())();
}