adding dotenv and envalid to manage environment variable properly

.gitignore

@@ -88,4 +88,4 @@
 /BackEnd/configs/OS.js
 /BackEnd/src/configs/OS.ts
 /BackEnd/dist
-
+/BackEnd/.env*

BackEnd/nodemon.json

@@ -2,7 +2,10 @@
     "events": {
         "start": "clear"
     },
+    "execMap": {
+        "ts": "ts-node -r dotenv/config"
+    },
     "ext": "ts",
-    "ignore": [".git", "node_modules", "dist"],
+    "ignore": [".git", "node_modules", "dist", "uploads"],
     "watch": ["./src"]
 }

BackEnd/package.json

@@ -20,7 +20,9 @@
     "body-parser": "^1.19.0",
     "child_process": "^1.0.2",
     "cors": "2.8.5",
+    "dotenv": "^10.0.0",
     "ejs": "3.1.5",
+    "envalid": "^7.1.1",
     "errorhandler": "1.5.1",
     "express": "^4.17.1",
     "express-generator": "^4.16.1",

BackEnd/src/env/db.ts

@@ -0,0 +1,2 @@
+export default {
+}

BackEnd/src/env/index.ts

@@ -0,0 +1,15 @@
+import { cleanEnv, str } from 'envalid'
+
+import serverEnv from './server'
+import dbEnv from './db'
+
+const env = cleanEnv(process.env, {
+  NODE_ENV: str({
+    choices: ['development', 'test', 'production']
+  }),
+
+  ...serverEnv,
+  ...dbEnv
+})
+
+export default env

BackEnd/src/env/server.ts

@@ -0,0 +1,19 @@
+import { bool, host, port, str } from 'envalid'
+import { ownDefault } from './utils'
+
+export default {
+  SERVER_HOSTNAME: host({ devDefault: 'localhost' }),
+  SERVER_PORT: port({ devDefault: 3000 }),
+
+  SERVER_DEBUG: bool({
+    desc: 'Allow to see more debug from like error handlers',
+    default: false,
+    devDefault: ownDefault({ dev: true, test: false, all: false })
+  }),
+  SERVER_MORGAN_FORMAT: str({
+    choices: ['combined', 'common', 'dev', 'short', 'tiny'],
+    default: 'combined',
+    devDefault: 'dev',
+    docs: 'https://www.npmjs.com/package/morgan#predefined-formats'
+  })
+}

BackEnd/src/env/utils.ts

@@ -0,0 +1,11 @@
+export function ownDefault<T> ({ dev, test, all }:
+                              {dev: T, test: T, all: T}) {
+  switch (process.env.NODE_ENV) {
+  case 'test':
+    return test
+  case 'development':
+    return dev
+  default:
+    return all
+  }
+}