feat: add CDN support in static export

Author: unix

README.md

@@ -123,7 +123,14 @@ In a few scenarios, you may want to deploy your blog on a CDN or other static se
 npm run export
 ```
 
-After running the command, the generated static file will be in the `/out` directory.
+After running the command, the generated static file will be in the `/out` directory. If you want to set the prefix of the CDN,
+please set the environment variable:
+
+```bash
+# set CDN prefix
+export CDN_PREFIX=https://unix.bio
+npm run export
+```
 
 <br />
 

README_CN.md

@@ -122,7 +122,13 @@ npx unix-bio migrate
 npm run export
 ```
 
-在运行命令后，静态文件会生成在 `/out` 文件夹。
+在运行导出命令后，静态文件会生成在 `/out` 文件夹。如果您想要自定义 CDN 的域名前缀，可以声明环境变量后再运行导出命令:
+
+```bash
+# cdn prefix
+export CDN_PREFIX=https://unix.bio
+npm run export
+```
 
 如果你使用自定义的静态部署，将无法获得最好的性能，同时未来所有与服务端渲染、混合渲染相关的功能也不受支持。
 此外，静态部署需要您自行解决各类路径与缓存问题。（请不要在 `issues` 中提此类问题）

next.config.js

@@ -1,3 +1,10 @@
+const isProd = process.env.NODE_ENV === 'production'
+const cdnPrefix = process.env.CDN_PREFIX || ''
+
+if (isProd && cdnPrefix) {
+  console.log(`> [unix.bio] You have customized the CDN prefix: ${cdnPrefix}.\n`)
+}
+
 const withMDX = require('@next/mdx')({
   extension: /\.(md|mdx)?$/,
   options: {
@@ -12,6 +19,12 @@ const nextConfig = {
 
   cssModules: true,
 
+  generateEtags: false,
+
+  poweredByHeader: false,
+
+  assetPrefix: isProd ? cdnPrefix : '',
+
   cssLoaderOptions: {
     importLoaders: 1,
     localIdentName: '[local]___[hash:base64:5]',