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I took a crack at installing Merb today, just to see how it works out. It’s a very minimal Ruby framework which in my (admittedly not very scientific) testing appears to be a lot faster than Rails, especially under conditions of high concurrency.

To get it running, I followed the instructions at the Merb book which is currently a work in progress at http://4ninjas.org. A quick tip: due to a dependency on extlib 0.9.3, the sake edgy technique didn’t work for me at first. I got it all running happily by doing the following.

First, install the Git source-code management tool and the Debian build tools if you don’t already have them:

sudo apt-get install build-essential git-core

sudo gem install rack mongrel json erubis mime-types rspec hpricot mocha rubigen haml markaby mailfactory  english addressable templater

Update: in the last few weeks gem dependencies have changed and you need to ensure you’ve got some specific versions available:

sudo gem install ruby2ruby --version=1.1.8

sudo gem install ParseTree --version=2.1.1

You’ll also need to ensure that you’ve got the MySql headers available in order to build the datamapper MySql libraries.

sudo apt-get install libmysqlclient15off libmysqlclient15-dev

git clone git://github.com/sam/extlib.git  
git clone git://github.com/sam/do.git

cd extlib
rake install ; cd ..
cd do
cd data_objects
rake install ; cd ..
cd do_mysql  # || do_postgres || do_sqlite3
rake install

For whatever reason, DataMapper 0.9.4 has a dependency on Merb-core 0.9.3, so you’ll need to install it and then proceed to build the newest DataMapper:

sudo gem install merb-core

git clone git://github.com/sam/dm-core.git
git clone git://github.com/sam/dm-more.git

cd dm-core ; rake install ; cd ..
cd dm-more
rake install; cd ..

After that stuff, the

sudo gem install sake
sake -i 'http://edgy.4ninjas.org/edgy.sake'
sake edgy:install packages="merb-stack"

commands worked just fine for me.

Bonus: install CouchDb, the wicked distributed database system which is currently an Apache incubator project.

sudo apt-get install build-essential erlang libicu38 libicu-dev libmozjs-dev
wget http://www.apache.org/dist/incubator/couchdb/0.8.0-incubating/apache-couchdb-0.8.0-incubating.tar.gz
tar -xvzf apache-couchdb-0.8.0-incubating.tar.gz 
cd apache-couchdb-0.8.0-incubating/
./configure
make && sudo make install

You can set up the CouchDb datastore as a service, with its own user, like this (thanks to these instructions, slightly modified to avoid the creation of a “couchdb” home directory):

sudo useradd couchdb
sudo mkdir -p /usr/local/var/lib/couchdb
sudo chown -R couchdb /usr/local/var/lib/couchdb
sudo mkdir -p /usr/local/var/log/couchdb
sudo chown -R couchdb /usr/local/var/log/couchdb
sudo mkdir -p /usr/local/var/run
sudo chown -R couchdb /usr/local/var/run

sudo cp /usr/local/etc/init.d/couchdb /etc/init.d/
sudo update-rc.d couchdb defaults
sudo /etc/init.d/couchdb start

After that, go to http://localhost:5984/_utils/index.html and you can administer your new distributed datastore. Of course, you could just ignore CouchDb and use Merb with a more “normal” database server like Mysql or Postgres.

If any of the version dependencies change again please leave a comment and I’ll update these instructions until Merb 0.9.4 is a little easier to get.