Merge pull request #3 from tusharmath/reading-env-variables

Reading env variables

README.md

@@ -5,6 +5,19 @@ node-config-ts
 
 A simple configuration manager for typescript based projects.
 
+## Table of contents
+1.  [Usage](#usage)
+
+2.  [Configuration](#configuration)
+
+    a.  [Using Files](#using-files) 
+
+    b.  [Using Environment Variables](#using-environment-variables) 
+
+    c.  [Using Commandline Params](#using-commandline-params)
+
+3. [Differences With Node Config](#differences-with-node-config)
+
 ## Usage
 
 1. Install package 
@@ -43,7 +56,16 @@ A simple configuration manager for typescript based projects.
     console.log(config) // logs the config data from default.json    
     ```
 
-## Directory Structure
+## Configuration
+The configs are merged in the following order of priority —
+
+1. Commandline params
+2. Environment variable
+2. User specific config file
+3. Deployment specific config file
+4. Environment specific config file
+
+### Using files
 Configurations are loaded via config files that are written in JSON format for now. A typical project looks like this —
 
 ```
@@ -63,7 +85,7 @@ root/
         └── sara.json
 ```
 
-There are three directories in which a project can have configurations — `deployment`, `env` and `user`. These directories can have multiple files inside them and based on the environment variables an appropriate config file is selected for overriding the base `default.json`. For instance if the `NODE_ENV` variable is set to `production` the `env/production.json` configuration will be merged with `default.json`. Similarly if `DEPLOYMENT` env variable is set to `staging.example.com` then `deployment/staging.example.com.json`  is merged with the other configs. Here is a table for environment to directory mapping —
+There are three directories in which a project can have configurations — `deployment`, `env` and `user`. These directories can have multiple files inside them and based on the environment variables an appropriate config file is selected for overriding the base `default.json`. For example if the `NODE_ENV` variable is set to `production` the `env/production.json` configuration will be merged with `default.json` and override default values with its own. Similarly if `DEPLOYMENT` env variable is set to `staging.example.com` then `deployment/staging.example.com.json`  is merged with the other configs. Here is a table for environment to directory mapping —
 
 
 | **process.env** | **directory**      |
@@ -72,16 +94,25 @@ There are three directories in which a project can have configurations — `depl
 | DEPLOYMENT      | /config/deployment |
 | USER            | /config/user       |
 
-## Configuration Priority
+### Using environment variables
+Whenever the value is prefixed with the letters `@@` **node-config-ts** automatically looks for an environment variable with that name. For example — 
 
-The configs are merged in the following order of priority —
+```json
+// default.json
+{
+  "port": "@@APP_PORT"
+}
+```
+In the above case automatically the value of `port` is set to the value that's available inside the environment variable `PORT`.
 
-1. Commandline
-2. User
-3. Deployment
-4. Environment
+```bash
+export APP_PORT=3000
+node server.js // server started with config.port as 3000
+```
 
-The command line arguments can override  all the configuration params. This is useful when you want to start a node server by passing the port externally  —
+### Using commandline params
+
+The command line arguments can override all the configuration params. This is useful when you want to start a node server by passing the port externally —
 
 ```bash
 node server.js --port 3000
@@ -94,6 +125,7 @@ In the above case even if the `default.json` has a port setting of `9000` the cl
     "port": 9000
 }
 ```
+
 ## Differences with node-config
 1. **No reserved words:** With [node-config] you can not use a certain set of [reserved words] in your configuration. This is an unnecessary restriction and `node-config-ts` doesn't have it.
 2. **Simpler API:** Instead of using methods such as `config.get('xxx')` in `node-config` you can simply use the exported `config` object.

index.ts

@@ -2,6 +2,6 @@
  * Created by tushar on 30/12/17.
  */
 
-import {loadAllConfigs} from './src/load-all-configs'
+import {mergeAllConfigs} from './src/mergeAllConfigs'
 
-export const config = loadAllConfigs(process) as Config
+export const config = mergeAllConfigs(process) as Config

package.json

@@ -20,7 +20,8 @@
     "cz-conventional-changelog": "^2.1.0",
     "mocha": "^4.1.0",
     "semantic-release": "^11.0.2",
-    "typescript": "^2.6.2"
+    "typescript": "^2.6.2",
+    "ts-node": "^4.1.0"
   },
   "config": {
     "commitizen": {

src/load-cli-configs.ts → src/loadCliConfigs.ts

@@ -11,6 +11,5 @@ import * as R from 'ramda'
  * @return {{cliConfig: any}}
  */
 export const loadCLIConfigs = (process: any) => {
-  const cliConfig = R.omit(['_'], minimist(process.argv))
-  return {cliConfig}
+  return R.omit(['_'], minimist(process.argv))
 }

src/load-file-configs.ts → src/loadFileConfigs.ts

@@ -5,7 +5,7 @@
  */
 import moduleExists = require('module-exists')
 import * as R from 'ramda'
-import {configPaths} from './config-paths'
+import {configPaths} from './configPaths'
 
 /**
  * Loads the configs provided in the {ConfigPaths}

src/mergeAllConfigs.ts

@@ -0,0 +1,19 @@
+/**
+ * Created by tushar on 30/12/17.
+ */
+import R = require('ramda')
+import {loadCLIConfigs} from './loadCliConfigs'
+import {loadFileConfigs} from './loadFileConfigs'
+import {replaceWithEnvVar} from './replaceWithEnvVar'
+import {mergeFileConfigs} from './mergeFileConfigs'
+
+/**
+ * Loads all the configs from files and cli and merges them.
+ */
+export const mergeAllConfigs = R.converge(R.mergeDeepRight, [
+  R.converge(replaceWithEnvVar, [
+    R.compose(mergeFileConfigs, loadFileConfigs),
+    R.identity
+  ]),
+  loadCLIConfigs
+])

src/merge-configs.ts → src/mergeFileConfigs.ts

@@ -1,24 +1,16 @@
 import * as R from 'ramda'
 
-export type ConfigSources = {
-  defaultConfig: any
-  envConfig: any
-  deploymentConfig: any
-  userConfig: any
-  cliConfig: any
-}
 /**
  * Merges the configs in the following order —
  * defaultConfig < envConfig < deploymentConfig < userConfig < cliConfig
  * @param {ConfigSources} configs
  * @return {any}
  */
 
-export const mergeConfigs = (configs: ConfigSources) => {
+export const mergeFileConfigs = (configs: {[key: string]: any}) => {
   return R.reduce(R.mergeDeepRight, configs.defaultConfig, [
     configs.envConfig,
     configs.deploymentConfig,
-    configs.userConfig,
-    configs.cliConfig
+    configs.userConfig
   ])
 }

src/replaceWithEnvVar.ts

@@ -0,0 +1,17 @@
+/**
+ * Created by tushar on 10/01/18.
+ */
+
+import * as R from 'ramda'
+
+const getVarName = R.replace('@@', '')
+const hasEnvVar = R.test(/^@@.*$/)
+export const replaceWithEnvVar = <T>(baseConfig: T, process: any) => {
+  const itar: any = R.map((value: any) => {
+    if (R.is(Object, value)) return itar(value)
+    if (R.is(String, value) && hasEnvVar(value))
+      return process.env[getVarName(value)]
+    return value
+  })
+  return itar(baseConfig)
+}

test/config-paths.test.ts → test/configPaths.ts

@@ -2,7 +2,7 @@
  * Created by tushar on 30/12/17.
  */
 import * as assert from 'assert'
-import {configPaths} from '../src/config-paths'
+import {configPaths} from '../src/configPaths'
 
 describe('config-paths', () => {
   describe('default', () => {