HTTP2 可用，但服务器拒绝使用它，为什么会这样？

Question

我已经成功地为我的虚拟主机设置了 http2，但是当我尝试通过 curl 访问 url 时，它看起来服务器拒绝通过 http2 连接并接受 http1。谁能解释为什么会这样？以及如何告诉我的服务器首先使用 http2。

以下是我尝试为其配置 http2 的站点的 curl 输出。

* Rebuilt URL to: https://example.com/
*   Trying 172.24.112.31...
* TCP_NODELAY set
* Connected to example.com (172.24.112.31) port 443 (#0)
* ALPN, offering h2
* ALPN, offering http/1.1
* successfully set certificate verify locations:
*   CAfile: /etc/ssl/certs/ca-certificates.crt
  CApath: none
} [5 bytes data]
* TLSv1.2 (OUT), TLS handshake, Client hello (1):
} [221 bytes data]
* TLSv1.2 (IN), TLS handshake, Server hello (2):
{ [112 bytes data]
* TLSv1.2 (IN), TLS handshake, Certificate (11):
    { [2426 bytes data]
* TLSv1.2 (IN), TLS handshake, Server key exchange (12):
{ [300 bytes data]
* TLSv1.2 (IN), TLS handshake, Server finished (14):
{ [4 bytes data]
* TLSv1.2 (OUT), TLS handshake, Client key exchange (16):
} [37 bytes data]
* TLSv1.2 (OUT), TLS change cipher, Client hello (1):
} [1 bytes data]
* TLSv1.2 (OUT), TLS handshake, Finished (20):
} [16 bytes data]
* TLSv1.2 (IN), TLS handshake, Finished (20):
{ [16 bytes data]
* SSL connection using TLSv1.2 / ECDHE-RSA-AES256-GCM-SHA384
* ALPN, server accepted to use http/1.1
* Server certificate:
*  subject: OU=Domain Control Validated; CN=*.example.com
*  start date: Jun  9 09:24:31 2016 GMT
*  expire date: Jun 10 09:24:31 2019 GMT
*  subjectAltName: host "example.com" matched cert's     "*.example.com"
*  issuer: C=BE; O=GlobalSign nv-sa; CN=GlobalSign Domain Validation CA - SHA256 - G2
*  SSL certificate verify ok.
} [5 bytes data]
> GET / HTTP/1.1
> Host: example.com
> User-Agent: curl/7.58.0
> Accept: */*
> 
{ [5 bytes data]
< HTTP/1.1 302 Found
< Date: Thu, 08 Mar 2018 08:54:23 GMT
< Server: Apache/2.4.29 (Ubuntu)
< Location: https://example.com
< Content-Length: 315
< Content-Type: text/html; charset=iso-8859-1
< 
{ [315 bytes data]
* Connection #0 to host example.com left intact

下面两行是我的重点，

* SSL connection using TLSv1.2 / ECDHE-RSA-AES256-GCM-SHA384
* ALPN, server accepted to use http/1.1

即使 http2 可用，它也不会被服务器使用，但会使用 http1.1。请帮助我理解这一点并以正确的方式配置 http2。

谢谢！

Answer 1

我在互联网上找到了解决方案，我正在更新它以帮助遇到同样问题的人。当我检查 apache 错误日志文件时，我发现了一个警告，类似于...

[http2:warn] [pid 8494] AH10034: The mpm module (prefork.c) is not supported by mod_http2. The mpm determines how things are processed in your server. HTTP/2 has more demands in this regard and the currently selected mpm will just not do. This is an advisory warning. Your server will continue to work, but the HTTP/2 protocol will be inactive.

然后经过一个小时的谷歌搜索，我开始知道这是在apache上配置HTTP2.0时prefork模块的问题。您可以在此位置找到有关此特定问题的更多信息以及配置 http2 的详细步骤。.

如果您不想在配置 http2 时遇到任何麻烦，我希望本文档对您有所帮助。

我按照这些步骤操作，我的问题就解决了。