Maps environment variables to JS types.

Example

Environment

Object.assign(process.env, {
  MOE_USE: 'false',
  MOE_MONGO_HOST: '127.0.0.1',
  MOE_MONGO_PORT: '27017',
  MOE_MONGO_DB: 'somedb',
  BOE_MONGO_OPTIONS_READ_PREFERENCE: 'secondary',
  MOE_REDIS_CLUSTER_USE: 'true',
  'MOE_REDIS_CLUSTER_HOSTS_0_HOST': '127.0.0.1', // changed from [0] to _0_ in 0.0.8
  'MOE_REDIS_CLUSTER_HOSTS_0_PORT': '6371',
  'MOE_REDIS_CLUSTER_HOSTS_1_HOST': '127.0.0.2',
  'MOE_REDIS_CLUSTER_HOSTS_1_PORT': '6372',
  'MOE_DARRAY_1_DVALUE': '21',
});

Mapping

const { parse, types } = require('mapofenv');
const { string, boolean, array, number } = types;

const mapping = {
  use: boolean(),
  redis: {
    cluster: {
      use: boolean(),
      hosts: array(2, {
        host: string(),
        port: number(),
      }),
    },
  },
  mongo: {
    host: string(),
    port: number(),
    db: string(),
    options: {
      readPreference: string('primary'),
    },
  },
  un: {
    host: string(),
    port: number(),
  },
  darray: array(2, {
    dvalue: number(20),
    svalue: string(),
  }, [{
    dvalue: 22,
    svalue: 'one',
  }])
};

Mapped Config

const config = parse(mapping, {
  prefix: ['BOE', 'MOE'], // first one wins if none found then null is set
});

Result

// const config will be
{
  use: false,
  redis: {
    cluster: {
      use: true,
      hosts: [{
        host: '127.0.0.1',
        port: 6371,
      }, {
        host: '127.0.0.2',
        port: 6372,
      }],
    },
  },
  mongo: {
    host: '127.0.0.1',
    port: 27017,
    db: 'somedb',
    options: {
      readPreference: 'secondary',
    },
  },
  un: {
    host: null,
    port: null,
  },
  darray: [{
    dvalue: 22,
    svalue: 'one',
  }, {
    dvalue: 21,
    svalue: null,
  }],
}

Available Types

• string(defaultValue)
• number(defaultValue)
• boolean(defaultValue)
• array(length, itemType, defaultValue)

Instead of given types, any function like the following can be used

function my(stringValueOfEnvVar) {
  // do something to the value
  return transformentValueOfEnvVar;
}