Installing Ruby’s linalg in Ubuntu

Ruby has a project for download called linalg that exposes the LAPACK functions in Ruby. LAPACK is a set of routines written in Fortran to do Linear Algebra operations. Now, before you cry foul about Fortran, LAPACK is used in a lot of places, and it’s pretty damn old and has held up over the years.

The linalg package just updated about two weeks ago, first since 2004, so it has some updates. Unfortunately, there’s no easy gem to install. You’ll have to download the tar, and then run

sudo ruby install.rb

Of course, you’ll run into some problems, unless you have other packages installed:

sudo apt-get install lapack3 lapack3-dev libg2c0-dev

Don’t worry, if you don’t like it, you can run uninstall. Read INSTALL file for more directions.
I use to wonder how people knew which packages to look for. Apparently, you look at the output and see what files the configure is crapping out on. Then use apt-file to search for which package the file is in. It’s one of those basic things that seems not mentioning in hindsight. Like calling “source ~/.bashrc” after you’ve edited your bash files. No one ever mentions that.

sudo apt-get install apt-file
sudo apt-file update
apt-file list g2c.h

Knowing that, you’ll know how to fish, and I’ll not post how to install stuff in the future.


Capistrano and Mongrel are easy to use, but deployment is still hard

So I finally got around to deploying with Capistrano. It was like learning how to walk all over again. Before, I had learned to deploy using just lightty behind apache, and that was a pain every time, since there would be steps I’d be forgetting. A good introduction to deploying with capistrano is “It’s time for a grown up server.” I also checked out Mongrel at the same time. It seems pretty neat.

I’m sure that Cappy is easy to use once it’s up and running, but boy, setting it up on a server from scratch has taken all day. This Yariv’s guy has a point when he says there’s so much stuff to install, compared to web development in Erlang–all you need is Yaws and Mnesia. But then again, all this ‘stuff’ is suppose to make our lives easier.

There are plenty of tutorials out there about setting up Capistrano and Mongrel, but deviate from them just a little, you’d better be ready to use your problem solving noggin.

SVN is just another TLA

One of the biggest problems I’ve run into while setting things up is that if you have a password on your svn repository, Cappy’s not going to like it too much. This is an old problem, and the old solution from Jamis exists. However, I noticed that when I used his solution, the options –username and –password was there twice. I’m guessing that you can do the following in your capistrano deploy.rb, and it would work…BUT!:

set :svn_username, ENV['USER'] || "default_username"
set :svn_password, { Capistrano::CLI.password_prompt('SVN Password: ') }
set :repository, "{application}/trunk"

This only works if the machine you’re developing on is the same as the machine that you’re deploying on, per the example in Agile Web Development with Rails (and already the example is outdated). When I did the cold deploy, I got this:

$ cap cold_deploy
* executing task cold_deploy
SVN Password:
...some other stuff clipped...
** [out :: remote_server] Authentication realm:
** [out :: remote_server] Password for 'someapp':
** [out :: remote_server] subversion is asking for a password
** [out :: remote_server] Authentication realm:
** [out :: remote_server] Username:

It seems like Capistrano checks the SVN twice. Once to find the latest version number when it is on the local development machine, and once again to checkout the latest version from the repository on the remote server machine. Since I had no way of controlling what goes on in the script while being executed on the remote machine, the prompts for a username and password for svn just got logged, and Cappy just waits on the local machine.

The only solution I came up with was just to go back to the Old Ways, where you ssh into the remote server machine and do a temp checkout by hand first. And you do the same on your local development machine.

$ svn co
$ rm -rf trunk

You can then just leave the deploy.rb script as:

set :repository, "{application}/trunk"

This way, svn caches your authentication on the remote machine (and local machine), and probably won’t ask for it again until maybe you reboot.

To get the pack of Mongrels running, you’d better get things right

Things were going hunky-dory, and I thought I was in the clear, but then there was a slight detour. I ran into this problem when I tried to start mongrel on the remote server.

$ mongrel_rails start -d
/usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/rails.rb:32: uninitialized constant Mongrel::HttpHandler (NameError)
from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:27:in `require'
from /usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/bin/mongrel_rails:10
from /usr/bin/mongrel_rails:18

This one took a little bit of time to figure out, but it was easier than the next two. Gems said that mongrel was successful at the end, when in fact, it didn’t build at all! This was because I didn’t have make on my machine. To get it on Ubuntu, apt-get the build-essential package, and then reinstall the mongrel and mongrel_cluster gems. Odd thing is, I needed make to build rubygems on Ubuntu. Must have got removed when I did apt-get autoremove

However, the real kicker stumped me for a while here:

$ cap cold_deploy
** transaction: commit
* executing task spinner
* executing task start_mongrel_cluster
* executing "sudo mongrel_rails cluster::start -C /var/www/apps/my_app/current/config/mongrel_cluster.yml"
servers: ["remote_server"]
[remote_server] executing command
command finished
command "sudo mongrel_rails cluster::start -C /var/www/apps/my_app/current/config/mongrel_cluster.yml" failed on remote_server

Huh? What’s going on? I was stumped for most of the day. It’s always the little thing that get you, but you learn, and alas you learn. Ubuntu, by default, does not add any subsequent users to sudo. I had created another user on the remote server machine to do the deployment. Therefore, it had no sudo privileges. Run:

sudo usermod -G admin username

And after that, I ran into:

$ cap cold_deploy
servers: ["remote_server"]
[remote_server] executing command
** [out :: remote_server] Starting 2 Mongrel servers...
** [out :: remote_server] !!! Path to log file not valid: log/mongrel.log
** [out :: remote_server] mongrel::start reported an error. Use mongrel_rails mongrel::start -h to get help.
** [out :: remote_server] mongrel_rails start -d -e production -p 8000 -a -P log/ -c /var/www/apps/my_app
** [out :: remote_server] !!! Path to log file not valid: log/mongrel.log
** [out :: remote_server] mongrel::start reported an error. Use mongrel_rails mongrel::start -h to get help.
** [out :: aeolus] mongrel_rails start -d -e production -p 8001 -a -P log/ -c /var/www/apps/my_app
command finished

After reading through some google posts, I realized it was really simple. The configuration file for mongrel had the wrong path to it. It didn’t have the right path. in the mongrel setup, you need to make sure the deploy path as “current” on the end. Remember to add /current/ to wherever you’re deploying your application!

mongrel_rails cluster::configure -e production -p 8000 -a -N 2 -c /deploy/path/my_app/current

So hopefully, if any of you out there has run into the same problems, I’ve saved you a little bit of time. I can’t really say this is a tip, more like a log of my adventures deploying. Remember, if just doing it once will save you lots of time in the future, it’s probably worth it to learn how to do it.

"Installing" net/https library in Ruby

This isn’t written anywhere that I’ve looked, so it’s either obvious, or I just missed the boat. But basically, in order to use the “net/https” library, you don’t need to download it. It’s included in the build of Ruby 1.8.4+

However, what you do need to install is both openssl, and the ruby-openssl packages for it in ubuntu in order for it to be working. Tip!

How to install Ruby 1.8.5 from source on Ubuntu

Well, it ends up that installing Ruby 1.8.5 and the associated Gems is a pain on Ubuntu. I’m here to take away that pain, yo.

Installing Ruby 1.8.5 from source

First, get the source tarball of 1.8.5 from the ruby lang web page, and put it in /usr/local/src

sudo tar -xvzf ruby-1.8.5-p12
cd ruby-1.8.5-p12
sudo ./configure
sudo make
sudo make install

If all goes well, you’re in business. But if it complains about “cannot open crt1.o”
(which is likely on Ubuntu), you’ll divine on google that it needs a “glibc-devel-2.3.3-74.i386” package. But I’ve done the legwork already, and under ubuntu, it’s actually called “libc6-dev”

sudo apt-get install libc6-dev

So try making Ruby again. It should be ok. If not, well, it’s not documented here, since I didn’t run into that problem.

What I did run into was more pain installing Gems.

Installing Ruby Gems from source

Again, go get the source tarball of ruby gems, and put it into /usr/local/src

sudo tar -xvzf rubygems-0.9.1
cd rubygems-0.9.1
sudo ruby setup.rb

Now, if all is well, you’re golden. But since this is Ubuntu, it’s likely that you’re missing zlib. So, some people seemed to have been able to get it to work from using the “zlib-ruby” package. What I had to do was install zlib from source.

Installing Ruby Zlib from source

Get the Ruby Zlib source and again put it into /usr/local/src/

sudo tar -xvzf ruby-zlib-0.6.0
cd ruby-zlib-0.6.0
sudo ruby extconf.rb

If that didn’t work, most likely, you got a bunch of stuff that said:

checking for deflateReset() in -lz... no
checking for deflateReset() in -llibz... no
checking for deflateReset() in -lzlib... no

That means that you need the headers for zlib. So install the package “zlib1g-dev”

sudo apt-get install zlib1g-dev

Then try it again. That should work, and once you get zlib installed, you can get gems up and running.