feat(core): support .env file to config environment variables

.gitignore

@@ -14,3 +14,4 @@ tmp
 *.swp
 *.iml
 coverage
+.env

docs/en/install/README.md

@@ -82,15 +82,14 @@ $ git pull
 
 `RSSHub` reads its configurations from `lib/config.js` or system environment variables.
 
-**How to set system environment variables**
+Create a `.env` file in the root directory of your project. Add environment-specific variables on new lines in the form of `NAME=VALUE`. For example:
 
-Under Windows, enter `$ set PORT=1000` in cmd
+```
+CACHE_TYPE=redis
+CACHE_EXPIRE=600
+```
 
-Under UNIX-based OS, enter `$ PORT=1000` in terminal
-
-Enter `$ npm start` to start a `RSSHub` install with port `1000`.
-
-System environment variables set here will be purged after closing cmd/terminal, if you want persist the variables, you can create a simple [batch script](https://en.wikipedia.org/wiki/Batch_file) or [shell script](https://en.wikipedia.org/wiki/Shell_script).
+Please notice that it will not override already existed environment variables, more rules please refer to [dotenv](https://github.com/motdotla/dotenv)
 
 To configure more options please refer to [Settings](#Settings).
 

docs/install/README.md

@@ -86,15 +86,14 @@ $ git pull
 
 可以通过设置环境变量来配置 RSSHub.
 
-**如何设置环境变量**
+在项目根目录新建一个 `.env` 文件，每行以 `NAME=VALUE` 格式添加环境变量，例如
 
-Windows 系统在 cmd.exe 中运行 `$ set PORT=1000`
+```
+CACHE_TYPE=redis
+CACHE_EXPIRE=600
+```
 
-macOS & Linux 运行 `$ PORT=1000`
-
-再运行 `$ npm start` 启动 RSSHub 即可将监听端口设置为 `1000`.
-
-此处设置的环境变量在关闭终端后就会被清除, 如果您想保存这些配置可以编写一个简单的 [批处理文件](https://en.wikipedia.org/wiki/Batch_file) 或 [shell](https://en.wikipedia.org/wiki/Shell_script).
+注意它不会覆盖已有的环境变量，更多规则请参考 [dotenv](https://github.com/motdotla/dotenv)
 
 更多配置项请看 [应用配置](#应用配置)
 

lib/index.js

@@ -1,3 +1,4 @@
+require('dotenv').config();
 const config = require('./config');
 const Koa = require('koa');
 const fs = require('fs');

package.json

@@ -55,6 +55,7 @@
     "co-redis": "2.1.1",
     "currency-symbol-map": "4.0.4",
     "dayjs": "1.8.13",
+    "dotenv": "8.0.0",
     "etag": "1.8.1",
     "form-data": "2.3.3",
     "git-rev-sync": "1.12.0",

yarn.lock

@@ -3550,6 +3550,11 @@ dot-prop@^4.1.0, dot-prop@^4.1.1:
   dependencies:
     is-obj "^1.0.0"
 
+dotenv@8.0.0:
+  version "8.0.0"
+  resolved "https://registry.yarnpkg.com/dotenv/-/dotenv-8.0.0.tgz#ed310c165b4e8a97bb745b0a9d99c31bda566440"
+  integrity sha512-30xVGqjLjiUOArT4+M5q9sYdvuR4riM6yK9wMcas9Vbp6zZa+ocC9dp6QoftuhTPhFAiLK/0C5Ni2nou/Bk8lg==
+
 double-ended-queue@^2.1.0-0:
   version "2.1.0-0"
   resolved "https://registry.yarnpkg.com/double-ended-queue/-/double-ended-queue-2.1.0-0.tgz#103d3527fd31528f40188130c841efdd78264e5c"