First, you'll need to be on one of WebFaction's CentOS7 servers, because the build tools on our older servers are too old to build nghttp2. If you're not on a CentOS7 server (web500 or higher, or one of our cloud plans) then you can request a migration via the control panel.

Once you're on a CentOS7 server, run the following commands to install nghttp2 and an updated curl in your home directory:

mkdir -p ~/tmp ~/src
export TMPDIR=~/tmp
cd ~/src
git clone https://github.com/tatsuhiro-t/nghttp2.git
cd nghttp2
autoreconf -i
automake
autoconf
./configure --prefix=$HOME
make
make install
cd ~/src
export LDFLAGS="-L$HOME/lib $LDFLAGS"
export LD_LIBRARY_PATH=$HOME/lib:$LD_LIBRARY_PATH
export PATH=$HOME/bin:$PATH
wget http://curl.haxx.se/download/curl-7.46.0.tar.bz2
tar -xvjf curl-7.46.0.tar.bz2
cd curl-7.46.0
./configure --prefix=$HOME --with-nghttp2=$HOME --with-ssl
make
make install

Next, run curl --vesion to ensure that you have the new version (7.46) installed. The output should look something like this:

curl 7.46.0 (x86_64-pc-linux-gnu) libcurl/7.46.0 OpenSSL/1.0.1e
zlib/1.2.7 libssh2/1.4.3 nghttp2/1.14.0-DEV
Protocols: dict file ftp ftps gopher http https imap imaps ldap
ldaps pop3 pop3s rtsp scp sftp smb smbs smtp smtps telnet tftp 
Features: IPv6 Largefile NTLM NTLM_WB SSL libz HTTP2 UnixSockets

Next, run curl --http2 -I nghttp2.org to ensure that HTTP/2 is working as expected. The output should look something like this:

HTTP/1.1 101 Switching Protocols
Connection: Upgrade
Upgrade: h2c

HTTP/2.0 200
date:Fri, 12 Aug 2016 18:12:19 GMT
content-type:text/html
last-modified:Thu, 21 Jul 2016 14:06:56 GMT
etag:"5790d700-19e1"
accept-ranges:bytes
content-length:6625
x-backend-header-rtt:0.001839
server:nghttpx nghttp2/1.14.0-DEV
via:2 nghttpx
x-frame-options:SAMEORIGIN
x-xss-protection:1; mode=block
x-content-type-options:nosniff

Next, create a PHP 7 application via the control panel if you've not done so already.

Next, create a file named my_php.cgi in your PHP 7 application's directory with the following contents, replacing "your_username" and "your_appname" with your user name and app name respectively:

#!/bin/sh

USERNAME=your_username
APPNAME=your_appname

# set the env variables
export LD_LIBRARY_PATH=/home/$USERNAME/lib

# run the original script via PHP CGI
exec /home/php-cgi/php70.cgi /home/$USERNAME/webapps/$APPNAME$SCRIPT_URL

Next, make the my_php.cgi script executable:

chmod 711 ~/webapps/your_appname/my_php.cgi

Finally, create a .htaccess file in your PHP 7 application directory (if you don't have one already) and add the following to it:

Action php_custom /my_php.cgi
<FilesMatch .php$>
    SetHandler php_custom
</FilesMatch>

That's it! When you're done, your PHP 7 application will be able to use the newer curl library with HTTP/2 support.

Note that this technique can be adapted to almost any CGI or PHP application that needs to use custom libraries or environment variables.