decode-env

A micro-library for decoding environment variables by name.

What?

This library provides a function which will decode specific environment variables, according to name patterns, into usable plaintext environment variables. By default, it will base64-decode all environment variables named like <FOO>_BASE64 into plaintext variables named like <FOO>. If the variables already exist, they will not be overwritten.

Why?

AWS Lambda environment variables may not contain commas. Certain types of secret strings commonly passed via environment variables, such as MongoDB connect strings, may contain commas. AWS CloudFormation templates provide an intrinsic function Fn::Base64 for base64-encoding values. To work around the limitation of Lambda, we may for example encode a MongoDB connect string into environment variable MONGO_URI_BASE64 in our CloudFormation template and run the decodeEnv function once at the beginning of our Lambda handler script to decode the value into another variable named MONGO_URI, as opposed to manually decoding it in every place that we use the value.

How?

For the base64 use case, simply require the module and run the decodeEnv function:

const decodeEnv = require('decode-env');

decodeEnv();

Or even more simply:

require('decode-env')();

For more complex use cases, you may specify an array of decoder mappings and an options object:

const decodeEnv = require('decode-env');
const mapping = require('decode-env/decoders/rot13').mapping;

decodeEnv([mapping], { overwrite: true });

The library includes decoder mappings for base64, rot-13, and uri-encoding, using the append strings BASE64, ROT13, and URLSAFE, respectively. You can easily write and employ custom decoder mappings as well.

Currently the only option supported is overwrite, which is a boolean indicating whether or not to overwrite existing environment variables. By default it is false.

For more usage details, see the examples.

License

This library is provided under the MIT License.