17-http2推送服务如何开启

两种方式开启:

• 服务端设置http头
• 客户端js/html标签属性，关键字preload

• nginx 1.13.9开始支持server push

  server {
    listen 443 ssl http2;
    server_name  localhost;
    ssl                      on;
    ssl_certificate          /etc/nginx/certs/example.crt;
    ssl_certificate_key      /etc/nginx/certs/example.key;
    ssl_session_timeout  5m;
    ssl_ciphers HIGH:!aNULL:!MD5;
    ssl_protocols SSLv3 TLSv1 TLSv1.1 TLSv1.2;
    ssl_prefer_server_ciphers   on;
    location / {
      root   /usr/share/nginx/html;
      index  index.html index.htm;
      http2_push /style.css;
    }
  }

  后端实现： ```javascript const http2 = require(‘http2’) const server = http2.createSecureServer( { cert, key }, onRequest )

function push (stream, filePath) { const { file, headers } = getFile(filePath) const pushHeaders = { [HTTP2_HEADER_PATH]: filePath }

stream.pushStream(pushHeaders, (pushStream) => { pushStream.respondWithFD(file, headers) }) }

function onRequest (req, res) { // Push files with index.html if (reqPath === ‘/index.html’) { push(res.stream, ‘bundle1.js’) push(res.stream, ‘bundle2.js’) }

// Serve file res.stream.respondWithFD(file.fileDescriptor, file.headers) }

Link: </styles.css>; rel=preload; as=style, </example.png>; rel=preload; as=image<br />服务器发现有这个头信息，就会进行服务器推送。
```javascript
server {
    listen 443 ssl http2;
    root /var/www/html;
    location = / {
        http2_push_preload on;
    }
}