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Nov
20
Setup Ruby Enterprise Edition, nginx and Passenger (aka mod_rails) on Ubuntu
By Antonio Cangiano. Filed under Quick Tips, Ruby, Ruby on Rails | 6 Comments
The following is a very short guide on setting up Ruby Enterprise Edition (REE), nginx and Passenger, for serving Ruby on Rails applications on Ubuntu. It also includes a few quick and easy optimization tips.
We start with setting up REE (x64), using the .deb file provided by Phusion:
wget http://rubyforge.org/frs/download.php/66163/ruby-enterprise_1.8.7-2009.10_amd64.deb
sudo dpkg -i ruby-enterprise_1.8.7-2009.10_amd64.deb
ruby -v
In output you should see “ruby 1.8.7 (2009-06-12 patchlevel 174)…” or similar. If this is the case, good; while you are there, update RubyGems and the installed gems:
sudo gem update --system
sudo gem update
Next, you’ll need to install nginx, which is a really fast web server. The Phusion team has made it very easy to install, but if you simply follow most instructions found elsewhere, you’ll get the following error:
checking for system md library ... not found checking for system md5 library ... not found checking for OpenSSL md5 crypto library ... not found ./configure: error: the HTTP cache module requires md5 functions from OpenSSL library. You can either disable the module by using --without-http-cache option, or install the OpenSSL library in the system, or build the OpenSSL library statically from the source with nginx by using --with-http_ssl_module --with-openssl=options.
Instead, we are going to install libssl-dev first and then nginx and its Passenger module:
sudo aptitude install libssl-dev
sudo passenger-install-nginx-module
Follow the prompt and accept all the defaults (when prompted to chose between 1 and 2, pick 1).
Before I proceed with the configuration, I like to create an init script and have it boot at startup (the script itself is adapted from one provided by the excellent articles at slicehost.com):
sudo vim /etc/init.d/nginx
The content of which needs to be:
#! /bin/sh
### BEGIN INIT INFO
# Provides: nginx
# Required-Start: $all
# Required-Stop: $all
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: starts the nginx web server
# Description: starts nginx using start-stop-daemon
### END INIT INFO
PATH=/opt/nginx/sbin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
DAEMON=/opt/nginx/sbin/nginx
NAME=nginx
DESC=nginx
test -x $DAEMON || exit 0
# Include nginx defaults if available
if [ -f /etc/default/nginx ] ; then
. /etc/default/nginx
fi
set -e
. /lib/lsb/init-functions
case "$1" in
start)
echo -n "Starting $DESC: "
start-stop-daemon --start --quiet --pidfile /opt/nginx/logs/$NAME.pid \
--exec $DAEMON -- $DAEMON_OPTS || true
echo "$NAME."
;;
stop)
echo -n "Stopping $DESC: "
start-stop-daemon --stop --quiet --pidfile /opt/nginx/logs/$NAME.pid \
--exec $DAEMON || true
echo "$NAME."
;;
restart|force-reload)
echo -n "Restarting $DESC: "
start-stop-daemon --stop --quiet --pidfile \
/opt/nginx/logs/$NAME.pid --exec $DAEMON || true
sleep 1
start-stop-daemon --start --quiet --pidfile \
/opt/nginx/logs/$NAME.pid --exec $DAEMON -- $DAEMON_OPTS || true
echo "$NAME."
;;
reload)
echo -n "Reloading $DESC configuration: "
start-stop-daemon --stop --signal HUP --quiet --pidfile /opt/nginx/logs/$NAME.pid \
--exec $DAEMON || true
echo "$NAME."
;;
status)
status_of_proc -p /opt/nginx/logs/$NAME.pid "$DAEMON" nginx && exit 0 || exit $?
;;
*)
N=/etc/init.d/$NAME
echo "Usage: $N {start|stop|restart|reload|force-reload|status}" >&2
exit 1
;;
esac
exit 0
Change its permission and have it startup at boot:
sudo chmod +x /etc/init.d/nginx
sudo /usr/sbin/update-rc.d -f nginx defaults
From now on, you’ll be able to start, stop and restart nginx with it. Start the server as follows:
sudo /etc/init.d/nginx start
Heading over to your server IP with your browser, you should see “Welcome to nginx!”. If you do, great, we can move on with the configuration of nginx for your Rails app.
Edit nginx’ configuration file:
sudo vim /opt/nginx/conf/nginx.conf
Adding a server section within the http section, as follows:
server {
listen 80;
server_name example.com;
root /somewhere/my_rails_app/public;
passenger_enabled on;
rails_spawn_method smart;
}
The server name can also be a subdomain if you wish (e.g., blog.example.com). It’s important that you point the root to your Rails’ app public directory.
The rails_spawn_method directive is very efficient, allowing Passenger to consume less memory per process and speed up the spawning process, whenever your Rails application is not affected by its limitations (for a discussion about this you can read the proper section in the official guide).
If you have lots of RAM (e.g., more than 512 MB) on your server, you may want to consider increasing you maximum pool size, with the directive passenger_max_pool_size from its default size of 6. Conversely, if you want to limit the number of processes running at any time and consume less memory on a small VPS (e.g., 128 to 256MB), you can decrease that number down to 2 (or something in that range). (Always test a bunch of configurations to find one that works for you). You can read more about this directive, in the official guide.
While you are modifying nginx’ configuration, you may also want to increase the worker processes (e.g., to 4, on a typical VPS) and add a few more tweaks (such as enabling gzip compression):
# ...
http {
passenger_root /usr/local/lib/ruby/gems/1.8/gems/passenger-2.2.5;
passenger_ruby /usr/local/bin/ruby;
include mime.types;
default_type application/octet-stream;
access_log logs/access.log;
sendfile on;
keepalive_timeout 65;
tcp_nodelay on;
gzip on;
gzip_comp_level 2;
gzip_proxied any;
server {
#...
When you are happy with the changes, save the file, and restart nginx:
sudo /etc/init.d/nginx restart
If you wish to restart Passenger in the future, without having to restart the whole web server, you can simply run the following command:
touch /somewhere/my_rails_app/tmp/restart.txt
Passenger also provides a few handy monitoring tools. Check them out:
sudo passenger-status
sudo passenger-memory-stats
That’s it, you are ready to go! I hope that you find these few notes useful.
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Oct
21
What is DB2 pureScale?
By Antonio Cangiano. Filed under DB2 | 3 Comments
There are two main types of scalability: vertical and horizontal. Vertical scalability consists of potentiating the hardware specs of a given server. This is typically done by increasing the number (and to a minor extent, speed) of the processors, adding more RAM, and so on. Commodity hardware tends to impose a strong limit on the resources that can be augmented. There is only so much that can be stuffed into your typical x64_86 Dell server, even replacing the entire machine with the top of the line model (having the same architecture). For this very reason, many customers opt to purchase more expensive hardware that has the advantage of facilitating vertical scalability, by allowing much more headroom for additional resources. This is why Unix-based solutions like IBM System p + AIX and Sun’s Solaris + SPARC are common choices in demanding environments.
For all their merits, even premium hardware solutions can only do so much in terms of vertical scalability. They may postpone the problem, by allowing a large number of processors and a huge amount of RAM to be installed, but they are still not limitless. And that’s when it becomes cheaper and much more feasible to attempt horizontal scalability, or the process of adding extra servers that share data and the overall system load.
Commercial databases, particularly DB2, excel at vertical scalability, which incidentally is one of the weakest aspects of open source RDBMS like MySQL. When it comes to horizontal scalability though, even commercial databases tend do struggle a little. Scalability is achieved, but a lot of work is required to configure complex setups involving masters, slaves, replication, failover servers, and so on. Until now.
IBM has just introduced a new technology for DB2 called pureScale, which accomplishes three incredible feats:
- Horizontal scalability: Virtually unlimited capacity by simply adding new nodes to the cluster.
- Application transparency: No code changes needed.
- Continuos data availability: regardless of which server fails, the system will continue to operate albeit with a proportionally reduced throughput.
DB2 pureScale applies to DB2 running on Unix (IBM System p running AIX only, for the moment), the same principles and rock solid technology employed by DB2 for z/OS Data Sharing and SYSPLEX. This technology happens to be employed by some of the largest companies in the world and it’s considered the golden standard when it comes to easily create OLTP database clusters, providing virtually unlimited scalability capabilities.
You can read more about it here and here. If you are going to IOD this year, don’t forget to attend this overview by one the architects of DB2 pureScale. And even if you can’t head over to Las Vegas next week, you can still attend online our Chat with the Lab today at 11:30am EST. Database scalability is a hot topic and this is going to be one of the most popular chats with the lab ever, so register for free now.
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Oct
19
Add code highlighting to your Google Waves
By Antonio Cangiano. Filed under General, Quick Tips | 5 Comments
Google Wave is still rough around the edges, but it has a lot of potential in terms of becoming a great collaboration tool. As a developer, your first question will probably be: “How do I add code highlighting to my waves?”. The answer is straightforward, however not very easy to find if you google it. I hope this post will help fellow developers who are experimenting with Google Wave.
The following steps are required to obtain syntax highlighting for your code:
- Create a new wave and add the Syntaxy robot to your wave. Use the wave address: kasyntaxy@appspot.com.
- Reply to your first message or within it, thereby creating a reply (called “blip” in Google lingo).
- Specify your code’s language, prefixing the name with a hash and exclamation mark, like #!python or #!ruby.
At this point, as you type the code in your blip it will be highlighted by the Syntaxy bot as shown in the picture below:
More advanced automatic syntax highlighting bots will probably appear as Google Wave progresses, but this one should do the trick for now. On a side note, if you copy and paste code from XCode, the code formatting will be kept in your waves and blips without the need for bots.
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