PHP RFC: Add HTTP/2 Support to the CLI Server


As more clients support HTTP/2 (e.g. 60% of browsers, curl, etc) we run into the issue of not being able to test new HTTP/2 functionality being added to PHP without external dependencies (e.g. a web server).

To solve this, it has been proposed that we update the cli-server to support HTTP/2.


For supporting HTTP/2, it is pretty well agreed 1) that we should use a third party library to implement it, with libnghttp2 being my proposed suggestion. We should ship with some self signed certs (it's for development only, remember!) that can be used to setup SSL, as no browser supports plain text HTTP/2.

Given that this introduces a new required dependency there are two ways we can implement this functionality:

  1. Make it optional, allowing you to build the current HTTP/1.x cli-server and requiring no additional dependency
  2. Make it required, but this also effectively requires libopenssl

It should be noted that libnghttp2 is also used by both curl and Apache 2, making it more likely that you already have it

With either implementation, we can also make HTTP/2 always enabled (if built in), or we can make it de/activated with a flag, such as: --[no-]http2. I believe we should have this flag as it makes it possible to test HTTP/1.x fallback for HTTP/2 clients, as well as HTTP/2.

In addition, we should consider adding the HTTP/2 SETTINGS to $_SERVER so we can both detect that the request is using HTTP/2 and make intelligent decisions on how the application performs (e.g. server push of multiple CSS files vs minifying/concatenating).

We should also support the ability to do server push using HTTP headers (current community thinking is leaning towards Link: <resource>; rel=preload header)

Backward Incompatible Changes

If we make this required for cli-server, then the new dependency requirement could be considered a BC break

Proposed PHP Version(s)

Next 7.x

RFC Impact

Adds a newly required dependency, libnghttp2


Adds HTTP/2 support to cli-server, potentially with a new flag. Meaning you could start the server like so:

php -S --http2 -t ./public/ ./public/index.html

To Existing Extensions


To Opcache

I do not believe this will affect opcache in any way

Open Issues

Unaffected PHP Functionality

Future Scope

Proposed Voting Choices

Patches and Tests

None yet, help needed


After the project is implemented, this section should contain

  1. the version(s) it was merged to
  2. a link to the git commit(s)
  3. a link to the PHP manual entry for the feature


Rejected Features

Keep this updated with features that were discussed on the mail lists.

see references
rfc/cli_server_http2.txt · Last modified: 2017/09/22 13:28 by