[Link] Bootstrapping passenger and Ruby Enterprise on Ubuntu

Michael Lang has provided a whole bunch of extremely useful scripts to help you install passenger and ruby enterprise on ubuntu. He's blogged about why he's provided the scripts - basically because he want everybody to bootstrap for his blogposts so they can start with the same environment set up before he goes into the details of a particular explanation.

I for one am simply grateful - but his comments are closed on the articles, so I guess I'll just have to point at him instead. :)

Thanks Michael!

Getting ffmpeg to work under ubuntu

I had a fair whack of trouble getting ffmpeg to compile on ubuntu. These are the steps I took that finally got it working for me.

Firstly - I'm going to assume you've downloaded and installed the appropriate libraries (codecs?) for the various audio/video formats that you are going to use (eg lame). I'm just going to cover making ffmpeg actually compile and run.

The usual set of steps will be

• Downloading ffmpeg: svn checkout svn://svn.mplayerhq.hu/ffmpeg/trunk ffmpeg
• cd ffmpeg
• Configuring appropriately to your build. Eg: ./configure --enable-libmp3lame --disable-vhook --disable-mmx --enable-nonfree --enable-gpl --enable-shared --enable-libamr-nb --enable-libfaad --enable-libx264 --enable-encoder=x264 --prefix=/opt/local --extra-ldflags=-L/opt/local/lib --extra-cflags=-I/opt/local/include
• make
• sudo make install

If that all works for you, then brilliant, but for me it fell over while trying to make, telling me it couldn't find x264. For some reason it's necessary to add --enable-pthreads to make it work on ubuntu.

The next big hurdle for me was that a bug appears in the v4l2 library for ubuntu. It doesn’t properly load some of the basic linux types. This is apparently a well-known bug in some of the older linux headers, and will stall the compilation of ffmpeg with a whole slew of bogus error messages, that essentially boil down to the __u64 and __s64 types failing to be defined appropriately.

To make a temporary fix, you can open up asm/types.h (I used find to find it) and figure out where the asm types are located on your distro (for me they’re in asm-i386/types.h).

Now, copy the two lines that define __u64 and __s64 and paste them into:
/usr/include/linux/videodev2.h just above their first use to help define v4l2_std_id

Note - this is an ugly, quick hack, but it should get the compilation going again. For a more permanent solution - I'd suggest chatting to the ubuntu people... or maybe it's time for me to get around to upgrading from feisty ;)

That will generally get you compiled and installed, but I then fell over a run-time bug that boiled down to an error message: “cannot find libavdevice.so.52”. This problem had me stalled for weeks. Google returns a lot of talk about the problem, but very few solutions, but eventually I stumbled across the answer: you need to add a library path to your environment thus:
export LD_LIBRARY_PATH=/usr/local/lib/

Finally ffmpeg safely up and running on ubuntu. Yay!

Updating gem to 1.2.0 on Ubuntu

Like several others, I tried to gem update today and failed. It gave me weird error telling me it couldn't find the update gem in the repository:

%> sudo gem update --system
Updating RubyGems
Bulk updating Gem source index for: http://gems.rubyforge.org/
Updating rubygems-update
ERROR:  While executing gem ... (Gem::GemNotFoundException)
    could not find rubygems-update locally or in a repository

Googling gave me a fair few other links to people with the same issue. The main one seems to be listed under this ruby-forum topic which started as the release-notes for the Gem update to version 1.2.0. People that had problems updating to this gem listed their steps-to-reproduce in the replies below, and I tried all the suggestions.

sudo gem update --system was the original command I tried and it gave me the error as above. All the fora on the topic insisted that the workaround is to run: gem install rubygems-update -v 1.1.1, but this just gave the same error. I did note that most of these people were on various flavours of Mac, and the pleas for help from those on Ubuntu were drifting away into the sky unheard...

One forum user said he tried the above from his gem directory and that worked for him...
but not for me...

I even tried reinstalling ruby/rubygems via apt-get, but the former was latest version, and the latter doesn't exist...

I was about ready to nuke the site from orbit... and reinstall from scratch and went to the rubyforge page for rubygems. This lists the source code, but I also noticed it had individual "upgrade" gems available for download. This saved me from my previous scorched-earth plan, and eventually resulted in success. For future reference:

1. copy rubygems-update-1.1.0.gem to a local directory
2. then run: sudo gem install rubygems-update-1.1.0.gem
3. repeat with rubygems-update-1.2.0.gem
4. then run update_rubygems

Now it's all fine and sudo gem update --system happily fetches my new gems as before.

Ruby on Postgres on Ubuntu

Agile web devlopment in Rails [1st ed] is a great book - really. But when it comes to installing Rails on postgres - lets just say that it wasn't really written with ubuntu in mind. This page has far better installation steps (including setting up your pg_hba.conf for dapper).

The new edition is available now and I've just ordered myself a copy... this one looks great too - but is still based around MySQL. They do point at the RailsOnUbuntu page for installation, though - which is good. Definitely follow the "recommended way"!