Node.JS module to retrieve configuration from environment variables

Question

I don't like the idea of sprinkling process.env all over the place and wanted to abstract it out a bit. I'm new to Node and know there must be a better way to do a few things.

1. Not repeat the name 4 times (twice as a string and twice as a field)
2. Any cleaner way to create properties and centralize existence checks than how I've done it? Mind you, I am trying to keep this Node 4.3.2 compatible sans Babel transpilers to keep it simple and working in AWS Lambda's NodeJs environment.

// module

module.exports = {

}

var configError = function (keyName) {
  console.error("ExternalVars error! Could not load a value for: "+keyName);
  process.exit(1);
}

// TODO: extract repeated function?
Object.defineProperty(module.exports, 'SAMPLE_SECRET', {
    get: function() {
        if (!process.env.SAMPLE_SECRET)
            configError('SAMPLE_SECRET');
        else
            return process.env.SAMPLE_SECRET;
    }
});

Object.defineProperty(module.exports, 'SAMPLE_SECRET_MORE', {
    get: function() {
        if (!process.env.SAMPLE_SECRET_MORE)
            configError('SAMPLE_SECRET_MORE');
        else
            return process.env.SAMPLE_SECRET_MORE;
    }
});

// usage example

var externalvars = require('./config/externalvars.js');

var sampleSecret = externalvars.SAMPLE_SECRET;
var sampleSecretMore = externalvars.SAMPLE_SECRET_MORE;

Answer 1

Disclaimer: since I'm not familiar with export/import realm, my suggestion below might be too naive and not work. If so, rather than only downvoting, thanks in advance for a little comment pointing me to a resource which would enlight how and why I'm wrong.

That's said, with merely my pure JS skills, here is how I'd work:

var keys = [
  'SAMPLE_SECRET',
  'SAMPLE_SECRET_MORE'
];
keys.forEach(function(keyName) {
  Object.defineProperty(module.exports, keyName, {
      get: function() {
          if (!process.env[keyName]) {
              console.error(
                "ExternalVars error! Could not load a value for: " + keyName
              );
              process.exit(1);
          } else {
              return process.env[keyName];
          }
      }
  });
});

Answer 2

Untested, but this should be equivalent to yours:

const requiredKeys = ['SAMPLE_SECRET', 'SAMPLE_SECRET_MORE']

const keyValues = requiredKeys.reduce((m,x) => {
  if (!process.env[x]) {
    console.error("ExternalVars error! Could not load a value for: "+keyName)
    process.exit(1)
  }
  m[x] = process.env[x]
  return m
}, {})

export default keyValues