/**
 * Return the value associated with the key. If the value is absent an error is thrown
 *
 * @param key property name in env file
 * @returns the value associated for the key
 * @throws Error if the key is not present
 */
export declare function envOrThrow(key: string): string;
/**
 * Return the value associated with the key. If the value is not present undefined is returned
 *
 * @param key property name in env file
 * @returns the value associated with the key or undefined
 */
export declare function envOptional(key: string): string | undefined;
/**
 * Return the value associated with the key. If the value is not present an error is thrown
 *
 * @param key property name in env file
 * @param logger a logger instance where the error will be logged
 * @returns the int value associated with the key
 * @throws Error if the key is not present
 */
export declare function envOrThrowInt(key: string): number;
/**
 * Return the value associated with the key. If the value is not present an error is thrown.
 *
 * Valid truthy env values are true TRUE 1, otherwise false will be returned if the key is present.
 *
 * @param key property name in env file
 * @returns the boolean value associated with the key
 * @throws Error if the key is not present
 */
export declare function envOrThrowBoolean(key: string): boolean;
/**
 * Parse the value of the env file and return it as a string array.
 *
 * The individual values are separated by a comma without spaces.
 *
 * e.g.
 * CURRENCIES = 'EUR,USD,'CHF'
 *
 * @param key property name in env file
 * @returns the string[] value associated with the key
 * @throws Error if the key is not present
 */
export declare function envOrThrowArray(key: string): string[];