About a month ago I wrote about how cool was to migrate to HHVM on OpenShift. Custom cartridge for Nginx + HHVM and MariaDB was running fast and I was really excited about the new stack. I was landing on a new, beautiful world.

About a week later I faced some problems because of disk space. Files took only 560MB over 1GB but OpenShift shell gave me an error for 100% disk usage (and a nice blank page on the home because cache couldn’t be written). I wasn’t able to understand why it was giving me that error. It probably depends on log files written by custom cartridge in other position inside of the filesystem. No idea. Anyway I had no time to go deeper so I bought 1 more GB of storage.

The day after I bought the storage blog speed goes down. It was almost impossible to open the blog and CloudFlare gives me timeout for half of the requests. Blog visits started to fall and I have no idea about how to fix that. Some weeks later I discover some troubles with My Corderwall Badges and Simple Sharer Button Adder but, in the OpenShift environment, I had no external caching system useful to handle this kind of problems.

I didn’t want to come back to MySQL and Apache but also trash all my articles wasn’t fun so I choose something I rejected 3 years ago: I took a standalone server.


First choice was Scaleway. It’s trendy and is BareMetal. 3.5€ for a 4 core ARM (very hipster choice), 2 GB RAM, 50 GB SSD server. New interface is cool, better then Linode and Digital Ocean, server and resources are managed easily. Unfortunately HHVM is still experimental on ARM and SSD are on SAN, and they aren’t so fast (100MB/s).

Next choice was OVH. New 2016 VPS SSD (available in Canadian datacenters) are cheap enough (3.5$) and offer a virtual core Xeon with 2 GB RAM and 10 GB SSD. Multicore performances are lower and you have a lot of less storage but is an X86-64 architecture and SSD is faster (250 MB/s). I took this one!

Unfortunately my preferences aren’t changed since my first post. I’m still a developer, not a sysadmin. I’m not a master in Linux configuration and my stack has several running parts and my blog was still unavailable. My beautiful migration on cutting edge technologies became an emergency landing.

Luckily I found several online tutorial which explain how to master the WordPress stack. In the next days I completed the migration and my new stack now runs on: Pound, Varnish, Nginx, HHVM, PHP-FPM and MariaDB. I hope to have enough time in the coming days to publish all the useful stuff I used for configuration.

For the moment I’m proud to share average response time of the home page: 342ms 🙂


Everything started on Heroku in October 2012 over their dynos with Heroku Postgres and continued on OpenShift in August 2013 over a LAMP stack based on Apache 2.4, PHP 5.3 and MySQL 5.1.

Now it’s time to to move my little blog on a modern stack. Best offer on OpenShift is a variation of the standard LEMP (we can call it: LEMP-HH) stack with HHVM 3.8, MariaDB 5.5 over NGINX 1.7.


Actually biggest performances improvement was achieved adding a good cache plugin a few months ago. I always used W3 Total Cache and WP Super Cache but, in this specific case, they are both complex to use because of the structure of OpenShift stack. Best solution I found is WP Fastest Cache plugin, one of the latest cache plugin I tested. Here is the stunning header of their website showing two beautiful cheetahs (are they cheetahs?).


Anyway coming back on new stack, there is no official bundle yet but you can create a new application using tengyifei’s HHVM 3.8 cartridge and adding OpenShift MariaDB 5.5 cartridge. I wasn’t able to run them on different gears (with scaling option activated and HAProxy) but seems fast enough on a single gear.

Filesystem structure is similar to the standard PHP bundle except for the application dir that is named www/ instead of php/. I used last backup from UpdraftPlus to migrate database on MariaDB. On non scalable applications you need to forward port in order to access DB from your local machine. RHC command is:

rhc port-forward -a application-name

Source here: Getting Started with Port Forwarding on OpenShift

Moving on NGINX also causes problems on permalinks because .htaccess doesn’t work anymore. The Nginx Helper plugin fix the problem but you could simply add a couple of row to NGINX configuration located in /config/nginx.d/default.conf.erb.

# Handle any other URI
location / {
try_files $uri $uri/ /index.php?q=$request_uri;

Discussion on WordPress support forum: WordPress Permalinks on NGINX

Refactor of previous filesystem, migration of database and bugfix of permalinks and other stuff takes about 2 hours and, at the end, everything seems working fine. I’m quite confident this a future proof solution but I’m going to test it until next major update 🙂

[UPDATE 2015-09-06 21:56 CEST]

After migration sitemap_index.xml and robots.txt weren’t reachable. Some rules were missing. I took the opportunity to switch to Yoast SEO for sitemap, Facebook open graph and Twitter cards. Then, these rules fix problems with SEO.

# Rewrites for WordPress SEO XML Sitemap
rewrite ^/sitemap_index.xml$ /index.php?sitemap=1 last;
rewrite ^/([^/]+?)-sitemap([0-9]+)?.xml$ /index.php?sitemap=$1&sitemap_n=$2 last;
# Rewrites for robots.txt
rewrite ^/robots\.txt$ /index.php?robots=1 last;

bedrock_big_logo During the last couple of weeks I had to work on a PHP project with a custom WordPress stack I have never used before: Bedrock.

The home page says “Bedrock is a modern WordPress stack that gets you started with the best development tools, practices, and project structure.“.

What Bedrock really is

It is a regular WordPress installation with a different folder structure and is integrated with composer for dependencies management and capistrano for deploy. The structure reminds Rails or similar frameworks but contains usual WordPress component and run on the same web stack.

├── composer.json
├── config
│   ├── application.php
│   └── environments
│       ├── development.php
│       ├── staging.php
│       └── production.php
├── vendor
└── web
├── app
│   ├── mu-plugins
│   ├── plugins
│   ├── themes
│   └── uploads
├── wp-config.php
├── index.php
└── wp

Server configuration

The project use to works on Apache with mod_php but I personally don’t like this stack. I’d like to test it on HHVM but at the moment I preferred to run it on nginx with PHP-FPM. Starting with an empty Ubuntu 14.04 installation I set up a LEMP stack with memcached and Redis using apt-get:

apt-get update
apt-get install build-essential tcl8.5 curl screen bootchart git mailutils munin-node vim nmap tcpdump nginx mysql-server mysql-client memcached redis-server php5-fpm php5-curl php5-mysql php5-mcrypt php5-memcache php5-redis php5-gd

Everything works fine except the Redis extension (used for custom function unrelated with WordPress). I don’t know why but the config file wasn’t copied into the configuration directory /etc/php5/fpm/conf.d/. You can find it among the available mods into /etc/php5/mods-available/.

PHP-FPM uses a standard configuration placed into /etc/php5/fpm/pool.d/example.conf. It listen on or unix socket in /var/run/php5-fpm-example.sock (I assume the configured name was “example”).

Memcached should be configured to be used for session sharing among multiple servers. To activate it you need to edit the php.ini configuration file setting the following parameters into /etc/php5/fpm/php.ini

session.save_handler = memcache
session.save_path = 'tcp://,tcp://'

nginx configuration is placed into /etc/nginx/sites-available/ and linked into /etc/nginx/sites-enabled/ as usual and forward request to PHP-FPM for PHP files.

server {
listen 80 default deferred;
root /var/www/example/htdocs/current/web/;
index index.html index.htm index.php;
server_name www.example.com;
access_log /var/www/example/logs/access.log;
error_log /var/www/example/logs/error.log;
location / {
try_files $uri $uri/ /index.php?q=$uri&$args;
location ~\.php$ {
try_files $uri =404;
# fastcgi_pass;
fastcgi_pass unix:/var/run/php5-fpm-example.sock;
fastcgi_index index.php;
fastcgi_buffers 16 16k;
fastcgi_buffer_size 32k;
include fastcgi_params;
location ~ /\.ht {
deny all;

Root directory will be web/ of Bedrock prefixed with current/ to support the capistrano directory structure displayed below.

├── current -> /var/www/example/htdocs/releases/20150120114500/
├── releases
│   ├── 20150080072500
│   ├── 20150090083000
│   ├── 20150100093500
│   ├── 20150110104000
│   └── 20150120114500
├── repo
│   └── <VCS related data>
├── revisions.log
└── shared
└── <linked_files and linked_dirs>

Local configuration

I’m quite familiar with capistrano because of my Ruby recent background. You need a Ruby version greater then 1.9.3 to run it (RVM helps). First step is to download dependencies. Ruby uses Bundler.

# run it to install bundler gem the first time
gem install bundler
# run it to install dependencies
bundle install

Bundler read the Gemfile (and Gemfile.lock) and download all the required gems (Ruby libraries).

Now the technological stack is ready locally and on server 🙂
I’ll probably describe how to run a LEMP stack on OS X in a next post. For the moment I’m assuming you are able to run it locally. Here is useful guides by Jonas Friedmann and rtCamp.

Anyway Bedrock could run over any LAMP/LEMP stack. The only “special” feature is the Composer integration. Composer for PHP is like Bundler for Ruby. Helps developers to manage dependencies in the project. Here is used to manage plugins, themes and WordPress core update.

You can run composer install to install libraries. If you update libraries configuration or you want to force download of them (maybe after a fresh install) run composer update.


Capistrano enable user to setup different deploy environment. A global configuration is defined and you need to specify only custom configuration for each environment. An example of /config/deploy/production.rb:

set :application, 'example'
set :stage, :production
set :branch, "master"
server '', user: 'user', roles: %w{web app db}

Everything else is inherited from global config where are defined all the other deploy properties. Is important to say that deploy script of capistrano on Bedrock only download source code from Git repo and run composer install for main project. If you need to run in on any plugin you new to define a custom capistrano task and run it after the end of deploy. For instance you can add in the global configuration the following lines in order to install dependencies on a specific plugin:

namespace :deploy do
desc 'Rebuild Plugin Libraries'
task :updateplugin do
on roles(:app), in: :sequence, wait: 5 do
execute "cd /var/www/#{fetch(:application)}/htdocs/current/web/app/plugins/anything/ && composer install"
after 'deploy:publishing', 'deploy:updateplugin'

Now you are ready to deploy your Bedrock install on server!
Simply run cap production deploy, restart PHP-FPM (service php5-fpm restart) and enjoy it 😀

Many thanks to Giuseppe, great sysadmin and friend, for support during development and deploy of this @#@?!?@# application.

phpday_logoI used to refer to me as “PHP Developer” for a long time. More or less from the beginning of my career to 2011 when I moved to Ruby as main language. Last time I worked for real using PHP, tools were still uncomfortable and community was huge but still messy. 4 years later everything seems changed. Several important companies (including Facebook) leverage on it and both core language and most popular tools are improved a lot.

Things like HHVM, HackFIG, Composer, PHP7 many more are rapidly evolving the PHP landscape so I decided to attend the PHPDay 2015 to meet the Italian community refresh my knowledge.

It was a really interesting event. I had the opportunity to meet several awesome people and chat with them about almost everything (quite often chats happened on the grass of the beautiful location in Verona 🙂 )


Davey Shafik (@dshafik), a funny guy from Engine Yard, talks about PHP7 and HHVM as major improvements for the core of PHP. Enrico Zimuel (@ezimuel), core developer of Zend Framework, talks about ZF3. Steve Maraspin (@maraspin) talks about his experience with async PHP and parallel processing. Bernhard Schussek (@webmozart), core developer of Symfony, talks about Puli: a framework agnostic tool fro resource sharing.

I strongly believe PHP is changed. It included many “good parts” from other languages and is now ready to became, with the Facebook endorsement, a first class language.

See you next year at PHPDay 2016 😀

hiphop_logoHipHop was one of the most notable thing came from the Facebook labs about PHP development. PHP is slow and limited. They can’t rewrite theirs entire codebase so they decided to make PHP better. HipHop is a simply PHP to C++ compiler (HPHPc). Converted code is compiled into a binary and performance improvements are about 6x.

Unfortunately HipHop has several downsides. For all the performance gains that HPHPc provided, the curve for further performance improvements had flattened. HPHPc did not fully support the PHP language, including the create_function() and eval() constructs. HPHPc required a very different push process, requiring a bigger than 1 GB binary to be compiled and distributed to many machines in short order.

hhvm_logoTo overcome these problems Facebook develops, starting from early 2010, the HHVM: a PHP virtual machine. HHVM builds on top of HPHPc, using the same runtime and extension function implementations. HHVM converts PHP code into a high-level bytecode. This bytecode is then translated into x64 machine code dynamically at runtime by a just-in-time (JIT) compiler similarly to C#/CLR or Java/JVM.

hack_logoFacebook also released Hack, a programming language for HHVM that can be seen as a new version of PHP which it allows programmers to use both dynamic typing and static typing.

HHVM supports major PHP open source projects like WordPress. Running this project on seems really easy. A little modification was needed but last version (3.9) no longer need this. HHVM can also run on Heroku using a custom buildpack available here: https://github.com/hhvm/heroku-buildpack-hhvm.

My first experiment was to run WordPress on Heroku using HHVM. First step is create a Heroku app using HHVM buildpack:

heroku create --buildpack https://github.com/hhvm/heroku-buildpack-hhvm

Then you can deploy a standard WordPress installation adding the following config.hdf (the HHVM configuration file)

Server {
DefaultDocument = index.php
Eval {
Jit = true
VirtualHost {
* {
Pattern = .*
RewriteRules {
dirindex {
pattern = ^/(.*)/$
to = $1/index.php
qsa = true
StaticFile {
FilesMatch {
* {
pattern = .*.(dll|exe)
headers {
* = Content-Disposition: attachment
Extensions {
css = text/css
gif = image/gif
html = text/html
jpe = image/jpeg
jpeg = image/jpeg
jpg = image/jpeg
png = image/png
tif = image/tiff
tiff = image/tiff
txt = text/plain

Warning: don’t miss a newline character on the last line or linter will fail and you will going to hate this project 😉

Everything works fine. You can add you favorite MySQL hosted service and run your WordPress 5 minutes installation. Almost every plugin seems 100% compatible, I tested most popular with no problem. Performances are better and you also have the opportunity to use Hack to develop new custom plugins.

Now I’m curious about how HHVM can improve my production installations of WordPress. About this I’m looking for an OpenShift cartridge for HHVM or someone want to collaborate to create a new one (the only I found on Github seems “young”). Anyone interested? Let me know!

A few hours after I posted about DataSift architecture, @choult, one of the about 25 ninjas who develop DataSift platform, tweet me.

The following SlideShare presentation by @stuherbert, another ninja, talks about the use of PHP in DataSift. Unlike what you may think, PHP is widely used in data processing.


System is decomposable in three major data pipelines:

  • Data Archiving (Adds new data to Historic Archive)
  • Filtering Pipeline (Filtering and delivery data in realtime)
  • Playback Pipeline (Filtering and delivery data from Historic Archive)

And PHP is used for many parts of these.


They use a custom build of PHP 5.3.latest with several optimizations and compiled-in extensions (ZeroMQ, APC, XHProof, Redis, XDebug). The also develop some internal components:

  • Frink, tweetrmeme’s framework
  • Stone: foundation of in-house test tools, Hornet and Storyteller (they probably open source a fork named Storyplayer).

Unfortunately I wasn’t able to find more details about these. Anyway, here is the presentation:


Informations about VKontakte, the largest european social network, and its infrastructure are very few and fragmented. The only recent insights, in english, about its technology is a BTI’s press release which talks about VK migration on their infrastructure. Everything was top secret.

Only on 2011 at Moscow HighLoad++Pavel Durov and Oleg Illarionov told something about the architecture of the social network and insights are collected into this post (in russian). 

VK seems not different than any other popular social network: is over a LAMP stack and uses many other open source technologies.

  • Debian is the base for their custom Linux distro.
  • nginx mange load balancing in front of Apache who runs PHP using mod_php and XCache as opcode cacher.
  • MySQL is the main datastore but a custom DBMS (written using C and based on memcached protocol) is used for some magics. memcached helps also page caching.
  • XMPP is used for messages and chats and runs over node.js. Availability is granted by HAProxy who handle the node’s fragility.
  • Multimedia files are stored using xfs and media encoding is made using ffmpeg.
  • Everything is distributed over more than 4 datacenters

vk_logoThe main difference betweek VK and other social network is about server functions: VK servers are multifunctional. There is no clear distinction between database servers or file servers, they are used simultaneously in several roles.

Load balancing between servers occurs on a layered circuit which includes at balancing DNS, as well as routing requests within the system, wherein the different servers are used for different types of requests. 

For example, microblogging is working on a tricky circuit using memcached protocol capability for parallel sending requests for data on a large number of keys. In the absence of data in the cache, the same request is sent to the storage system, and the results are subjected to sorting, filtering and discarding the excess at the level of PHP-code.

The custom database is still a secret and is widely used in VKontakte. Many services use it: private messages, messages on the walls, statuses, search, privacy, friends lists and probably more. It uses a non-relational data model, and most operations are performed in memory. Access interface is an advanced protocol memcached. Specially compiled keys return the results of complex queries. They said is developed “best minds” of Russia.

I wasn’t able to find any other insight about VK infrastructure after this speech. They are like KGB 😀

It’s about half an year I want to move my blog away from Heroku. It’s the best PaaS I ever used but the free plan has a huge limit: the dynos idle. In a previous post i talked about how to use Heroku to build a reverse proxy in front of AppFog to avoid theirs custom domain limit but the idle problem is still there. My blog has less than 100 visits per day and almost every visitor has to wait 5-10 seconds to view home page because dynos are always idle.

openshift_logoToday I decided to move to another platform suggested by my friend @dani_viga: OpenShift. It’s a PaaS similar to Heroku which use Git to control revision and has a similar scaling system. And the free plan hasn’t the idle problem and it’s 10 times faster!

I created a new application using the following cartridge: PHP 5.3, MySQL 5.1 (I’d like to use MariaDB but cartridge is still in development and I couldn’t install it) and phpMyAdmin 3.4. They require a Git repo to setup application and provide a WordPress template to start. I used it as template moving code of my blog into /php directory.

The hard part was to migrate my PostgreSQL database into the new MySQL. To start I removed PG4WP plugin following installation instruction in reverse order.

Then I exported my PostgreSQL database using heroku db:pull command. It’s based on taps and is really useful. I had some problems with my local installation of MySQL because taps has no options about packet size and character set so you must set them as default. I added a few line to my.cnf configuration:

# enlarged, before was 1M
max_allowed_packet = 10M
# default to utf-8

At the end of the pull my local database contains a exact copy of the Heroku one and I can dump to a SQL file and import into the new MySQL cartridge using phpMyAdmin.

The only problem I had was about SSL certificate. The free plan doesn’t offer SSL certificate for custom domain so I have to remove the use of HTTPS for the login. You can do in the wp-config.php setting:

define('FORCE_SSL_ADMIN', false);

Now my blog runs on OpenShift and by now seems incredibly faster 😀

Yesterday I had to re-deploy the WordPress installation of PrimeGap.net on a new server and, looking for some tips about configuration, I found a new strange buzzword: LEMP Stack. 

We all know the LAMP Stack and we all know it’s old, slow and hard to scale. It includes any distribution of Linux, Apache with PHP as a module and MySQL 5.x.

A LEMP Stack is a bit different. First of all it uses nginx (pronounced “engine x”) and this explain the “E”. Then you can replace MySQL with any of the other fork. I personally use MariaDB 10.0. Many people also use Percona.

You can also replace PHP with another language such Python or Ruby but if you still use PHP choose PHP-FPM.

Many hosting provider provide useful guides to setup you server:

Linode is a bit different and uses PHP-FastCGI. Both uses MySQL. If you, like me, prefer MariaDB following guides should help you:

Current version of WordPress is easy to run on it. WordPress Codex provides a custom configuration to uses nginx. There are many optimization you can do. This Gist seems well done: https://gist.github.com/tjstein/902803

Welcome to the next-gen 🙂

When your WordPress blog gets bigger and traffic grows you have to handle cache. No excuse: is a fast, cheap and optimized way to deal with traffic problems.

W3 Total Cache and WP Super Cache are the most popular plugins to handle cache on WordPress which works well but I don’t like them. They are a good choice only if you don’t have many customizations or some hardware constrain. Recently I had many problems with both two because of other caching systems and some problems on the server.

Now if I have to activate cache on a production stack formed by Apache + PHP-CGI + WordPress I certainly choose nginx.

Using nginx you can activate a fully customized cache layer in front of your website. Unfortunately WordPress doesn’t support nginx cache natively. You need a plugin to deal with it: the WordPress Nginx proxy cache integrator. The code is below:

function add_xaccel_header() {
// Set the X-Accel-Expires header to never cache the page
// if it looks like the page needs to be tailored
// for a user.
$user_cookie_there = false;
foreach($_COOKIE as $key => $value){
if( preg_match('/wordpress_(?!test_cookie)|comment_author|wp-postpass/', $key) ){
$user_cookie_there = true;
header("X-Accel-Expires: 0");

The plugin sets a cookie to enable nginx to discriminate between logged and guest user and not cache pages for authors. Default behavior for nginx is to not cache any pages if a cookie is set.

After you had set this plugin you can put nginx in front of Apache. The authors of the plugin suggest an optimal configuration but I prefer a simpler one written by my friend @dani_viga on his blog.

[UPDATE 2013-03-05] Look at the post (finally public :))

In addition, to speed up IO (server’s NAS has some latency problems), we use a ramdrive to store cache files. We also had to disable mod_deflate in order to solve some problems when you active gzip compression before nginx.

Now average response time is under 100 ms, static contents are served without Apache and there is no potentially problematic plugin to manage. And purge cache takes less then 3 secs. 😀