WordPress Multisite on CentOS 7.2, Nginx 1.9.5, PHP7, batcache, and HTTP/2

It was time for an overhaul of my go-to WordPress stack. For a long while, I’ve been running PHP 5.4 on CentOS 6 with Varnish. Technical times are changing and it was overdue for an upgrade; so I bring you this!

My first impression of PHP 7 – WOW, Just WOW! The speed increase is phenomenal compared to PHP 5. It seems like the browser is no longer waiting on the server, but the other way around. WordPress is so fast on this setup that it feels like a native app. Perhaps even better/faster than a native app. I almost can’t believe it.

As for HTTP/2 – supposedly this new protocol is faster, but I don’t really see a huge difference with it on versus off. I’m sure its advantages will become apparent over time when we start to integrate more technology into our websites.

I decided to go away from varnish since I’m now running Batcache. Previously, I was a fan of W3TC, but have migrated away from that plugin (it’s become a bloated/buymebuyme nightmare now). This means you lose support for gzip, browser caching, and CDN settings from within WordPress, but you don’t really need to worry about those settings after they’re manually set up in Nginx anyways. Anyways, Batcache versus Varnish – I don’t really see a huge difference. If anything, the cache invalidation is much easier with Batcache. It’s a set-it-and-forget-it type of system and it “just works”.

On one of my production machines running this stack, I show load averages dropping from 3-4 down to less than 1. This is on a 16-core server, so that’s a significant performance gain. Again – I almost can’t believe it, but the numbers speak for themselves. As for memory usage, I don’t see much difference, but everything looks good and clean.

Specifications

Prerequisites

sudo yum update # update the system
sudo iptables -F # Flush iptables - we'll rebuild later
sudo yum install epel-release # Install EPEL repo
sudo yum install https://mirror.webtatic.com/yum/el7/webtatic-release.rpm
sudo yum install zlib-devel make gcc

Now, download the latest nginx source to a convenient location and compile it.

The Nginx Build

./configure \
--user=nginx \
--group=nginx \
--prefix=/etc/nginx \
--sbin-path=/usr/sbin/nginx \
--conf-path=/etc/nginx/nginx.conf \
--pid-path=/var/run/nginx.pid \
--lock-path=/var/run/nginx.lock \
--error-log-path=/var/log/nginx/error.log \
--http-log-path=/var/log/nginx/access.log \
--with-http_gzip_static_module \
--with-http_stub_status_module \
--with-http_ssl_module \
--with-pcre \
--with-file-aio \
--with-http_realip_module \
--with-http_v2_module \
--without-http_scgi_module \
--without-http_uwsgi_module

Then, of course, make and make install and nginx should compile. You can test this with /usr/sbin/nginx -c /etc/nginx/nginx.conf. You’ll want to kill that process after you test it.

Next, you need to be able to start/stop/reload nginx. Add this script to /etc/init.d/nginx:

#!/bin/sh
#
# nginx - this script starts and stops the nginx daemon
#
# chkconfig:   - 85 15
# description:  NGINX is an HTTP(S) server, HTTP(S) reverse \
#               proxy and IMAP/POP3 proxy server
# processname: nginx
# config:      /etc/nginx/nginx.conf
# config:      /etc/sysconfig/nginx
# pidfile:     /var/run/nginx.pid

# Source function library.
. /etc/rc.d/init.d/functions

# Source networking configuration.
. /etc/sysconfig/network

# Check that networking is up.
[ "$NETWORKING" = "no" ] & exit 0

nginx="/usr/sbin/nginx"
prog=$(basename $nginx)

NGINX_CONF_FILE="/etc/nginx/nginx.conf"

[ -f /etc/sysconfig/nginx ] & . /etc/sysconfig/nginx

lockfile=/var/lock/subsys/nginx

make_dirs() {
   # make required directories
   user=`$nginx -V 2>&1 | grep "configure arguments:" | sed 's/[^*]*--user=\([^ ]*\).*/\1/g' -`
   if [ -z "`grep $user /etc/passwd`" ]; then
       useradd -M -s /bin/nologin $user
   fi
   options=`$nginx -V 2>&1 | grep 'configure arguments:'`
   for opt in $options; do
       if [ `echo $opt | grep '.*-temp-path'` ]; then
           value=`echo $opt | cut -d "=" -f 2`
           if [ ! -d "$value" ]; then
               # echo "creating" $value
               mkdir -p $value & chown -R $user $value
           fi
       fi
   done
}

start() {
    [ -x $nginx ] || exit 5
    [ -f $NGINX_CONF_FILE ] || exit 6
    make_dirs
    echo -n $"Starting $prog: "
    daemon $nginx -c $NGINX_CONF_FILE
    retval=$?
    echo
    [ $retval -eq 0 ] & touch $lockfile
    return $retval
}

stop() {
    echo -n $"Stopping $prog: "
    killproc $prog -QUIT
    retval=$?
    echo
    [ $retval -eq 0 ] & rm -f $lockfile
    return $retval
}

restart() {
    configtest || return $?
    stop
    sleep 1
    start
}

reload() {
    configtest || return $?
    echo -n $"Reloading $prog: "
    killproc $nginx -HUP
    RETVAL=$?
    echo
}

force_reload() {
    restart
}

configtest() {
  $nginx -t -c $NGINX_CONF_FILE
}

rh_status() {
    status $prog
}

rh_status_q() {
    rh_status > /dev/null 2>&1
}

case "$1" in
    start)
        rh_status_q & exit 0
        $1
        ;;
    stop)
        rh_status_q || exit 0
        $1
        ;;
    restart|configtest)
        $1
        ;;
    reload)
        rh_status_q || exit 7
        $1
        ;;
    force-reload)
        force_reload
        ;;
    status)
        rh_status
        ;;
    condrestart|try-restart)
        rh_status_q || exit 0
            ;;
    *)
        echo $"Usage: $0 {start|stop|status|restart|condrestart|try-restart|reload|force-reload|configtest}"
        exit 2
esac

Okay, the hard part is over with. If you can start and stop nginx with service nginx start and service nginx stop, then you’re good to go. Time to have some fun. Let’s install some more software.

# Install memcached
sudo yum install -y memcached

# Install mariadb (mysql)
sudo yum install -y mariadb-server mariadb-client

# Install PHP 7
sudo yum install -y php70w php70w-fpm php70w-mysql php70w-opcache php70w-devel php70w-gd php70w-mbstring php70w-xml

# Install ntp, set timezone, set date
sudo yum install -y ntp ntpdate
sudo mv /etc/localtime /etc/localtime.bk
sudo ln -s /usr/share/zoneinfo/America/New_York /etc/localtime
sudo ntpdate pool.ntp.org

# Install some other tools that you'll want to have ready
sudo yum install -y vim htop screen

Configure Nginx

Now you’ll want to set up your nginx.conf and conf.d/* files how you want them. Some key things to remember:

  • If you want to use HTTP/2, you’ll need SSL. If you want free (and easy) SSL certificates, check out LetsEncrypt.
  • On WordPress Multisite (subdomain installs), you’ll want a certificate for each subdomain and each mapped domain. That means you will need a minimum of two certificates for your root domain, and two certificates for each subsequent mapped domain. Each *.yourdomain.com subdomain requires it’s own certificate, and each domain you map to a subdomain requires yet another.

The default nginx.conf is probably okay, though nginx may complain about one or more listen directives (if so, just change whatever it says to change). Here a sample default.conf that includes WordPress rewrite support, concatenation, browser caching, and gzip:

server {
	listen 80;
	server_name {{ actual_hostname }};

	root {{ actual_webroot }};
	index index.php index.html index.htm;

	client_max_body_size 100M;

	gzip on;
	gzip_disable "msie6";
	gzip_vary on;
	gzip_proxied any;
	gzip_comp_level 6;
	gzip_buffers 16 8k;
	gzip_http_version 1.1;
	gzip_types text/plain application/json application/x-javascript application/xml application/xml+rss text/javascript;

	error_page 404 /404.html;
	location /404.html {
		root {{ actual_webroot }};
	}

	error_page 500 502 503 504 /50x.html;
	location = /50x.html {
		root {{ actual_webroot }};
	}

	location / {
		try_files $uri $uri/ /index.php?q=$uri&$args;
	}

	# Allow access to script concatenation engine
	location /_static/ {
		fastcgi_pass unix:/var/run/php-fpm/php-fpm.sock;
		include /etc/nginx/fastcgi_params;
		fastcgi_param SCRIPT_FILENAME $document_root/wp-content/mu-plugins/http-concat/ngx-http-concat.php;
		include fastcgi_params;
	}

	# Browser cache static assets and do not access log
	location ~* \.(jpg|jpeg|gif|png|css|js|ico|svg)$ {
		expires max;
		access_log off;
		log_not_found off;
	}

	# Block access to PHP files in uploads
	location ~* /(?:uploads|files)/.*\.php$ {
		deny all;
	}

	# Whitelist IPs for nginx status
	location /nginx_status {
		stub_status on;
		access_log off;
		allow 127.0.0.1;
		deny all;
	}

	# All PHP files
	location ~ \.php$ {
		try_files $uri $uri/ /index.php?q=$uri&$args;
		fastcgi_pass unix:/var/run/php-fpm/php-fpm.sock;
		fastcgi_index index.php;
		fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
		include fastcgi_params;
	}
}

This file came from my ansible install.yml so you’ll need to make a few obvious string replacements. You’ll also want to duplicate this into ssl.conf and modify accordingly to accommodate your domain(s) and SSL requirements. Activating HTTP/2 is as easy as modifying the listen directive to reflect listen 443 ssl http2;.

There are a ton of other configuration items to address and tweak, such as php.ini and /etc/php-fpm.d/www.conf, and don’t forget to set up /etc/sysconfig/memcached… but I’ll leave those fine details to you. Remember to build your firewall also.

As always, if you need pointers, feel free to hit me up in the comments.

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