import { EnvSource, EnvConfig } from './types';
export declare const staticSource: () => EnvSource;
export declare const environmentSource: () => EnvSource;
export declare const stringSource: (source: string) => EnvSource;
export declare const configFileSource: (path: string) => EnvSource;
/**
 * Parse dotenv style environment.
 * Source are read in order and latest occurence will override the former ones (ie source needs to be
 * in decreasing order of priority)
 *
 * This function might return an error, but will always return an environment with whatever it could get.
 * This is useful when failing is not a option (for logging config for example)
 */
export declare const readEnvConfig: (sources: EnvSource[]) => Promise<{
    error: Error | null;
    env: EnvConfig;
}>;