[WordPress][Nginx] Nginx 1.13.9 に実装された http2_push_preload を使って HTTP/2 push してみる ref: https://qiita.com/wokamoto/items/63b47c1b320807d6380b

file0.txt

$ sudo /opt/local/provision
$ nginx -v
nginx version: nginx/1.13.9

file1.txt

server {
  :
    http2_push /wp-content/themes/twentyseventeen/style.css?ver=4.9.4;
  :
}

file2.txt

server {
  :
    http2_push_preload on;
  :
}

file3.txt

Link: </wp-content/plugins/amazon-polly/public/css/amazonpolly-public.css?ver=1.0.0>; rel=preload; as=style,  </wp-content/themes/twentyseventeen/style.css?ver=4.9.4>; rel=preload; as=style
Link: </wp-content/plugins/amazon-polly/public/js/amazonpolly-public.js?ver=1.0.0>; rel=preload; as=script,  </wp-content/themes/twentyseventeen/assets/js/skip-link-focus-fix.js?ver=1.0>; rel=preload; as=script,  </wp-content/themes/twentyseventeen/assets/js/global.js?ver=1.0>; rel=preload; as=script,  </wp-content/themes/twentyseventeen/assets/js/jquery.scrollTo.js?ver=2.1.2>; rel=preload; as=script

file4.txt

Link: </app/style.css>; rel=preload; as=style; nopush
Link: </app/script.js>; rel=preload; as=script

file5.txt

Link: </app/style.css>; rel=preload; as=style, </app/script.js>; rel=preload; as=script

http2_push.php

<?php
/*
Plugin Name: HTTP/2 Push
Plugin URI: 
Description: HTTP/2 Push
Author: wokamoto
Version: 0.0.1
Author URI: http://dogmap.jp/

License:
 Released under the GPL license
  http://www.gnu.org/copyleft/gpl.html
*/
add_action('template_redirect', function(){
    if ( headers_sent() ) {
        return;
    }

    do_action('wp_enqueue_scripts');

    foreach( array('style' => wp_styles(), 'script' => wp_scripts()) as $as => $wp_links ) {
        $link = '';
        foreach ( $wp_links->queue as $handle ) {
            if ( $wp_links->registered[$handle] && ! preg_match('/-ie8$/i',$handle) && 'html5' !== $handle ) {
                $wp_link = $wp_links->registered[$handle];
                $src = preg_replace('#^https?://[^/]+#', '', $wp_link->src);
                $ver = $wp_link->ver ? $wp_link->ver : $wp_links->default_version;
                $link .= !empty($link) ? ', ' : '';
                $link .= " <{$src}?ver={$ver}>; rel=preload; as={$as}";
                //header("Link: <{$src}?ver={$ver}>; rel=preload; as={$as}", false);
            }
        }
        if ( !empty($link) ) {
            header("Link:{$link}", false);
        }
    }

}, 0, 1);