Lone Star Ruby Conference

I just got home from the Lone Star Ruby Conference. Of course I'm suffering from all the post conference side effects...bags under my eyes and a brain that feels like it's going to explode.

I just wanted to quickly get a few things out there:

LSRC is such a well run conference

Of course, Lone Star Ruby Conference is a great conference but what strikes me is how well it is organized and run. Everyone associated with putting on the conference should be very proud of the work they do.

It's always about the people.

Everyone always says it but that's because it's true. It was great getting to spend time with (in order of appearance) Jason, Wynn, Tim, Glenn, Dave, Mike, Marlon, Jim, Geof, Mike, Adam, James, Dana, Dan, Elena, Jeremy, Evan, Tim and Jeremy. (Sorry if I missed anyone!) Each person brings a whole set of smarts and experiences to our community and I'm always impressed just being privileged to their conversations.

But it's also about the code.

Being fully immersed into Ruby land for 3 days is like a breath of fresh air. The training day before the conference was well worth it and each talk on Friday/Saturday, whether it was technical in nature or not, helped make me a better programmer.

I know it will be a busy week catching up from being gone, but it was well worth it!

yaml.rb

I spent some time last week working on a problem that had me digging into Ruby's Standard Library implementation of yaml. I thought I'd take a few minutes to share some thoughts

Deep Serialization

To me, this was the reason I was using yaml over json or xml in the first place. I was in Rails and was eager loading an ActiveRecord object. I'd expect the #to_xml or #to_json methods to create a deeply nested structured document including all the associations I eager loading. But that's not the case.

However I was pleasantly surprised to find that #to_yaml did in fact do this. (It's not exactly apples to apples, #to_yaml is part of the Ruby Standard Library and #to_json and #to_xml are implemented in Rails.)

This was the home run feature for me so yaml and I started to get close.

Smart Class Transformations

Let's say our test.yml file looks like this:

--- !ruby/object:Family
kids:
  !ruby/object:Kid
    name: Beef
- !ruby/object:Kid 
    name: OshGosh
name: McSpadden

If you fire up irb and do:

require 'yaml'
YAML.load(File.read(test.yml))

You'll get something like:

#<YAML::Object:0x580408 @ivars={"name"=<"McSpadden", "kids"=>[#<YAML::Object:0x580660 @ivars={"name"=>"OshGosh"}, @class="Kid">]}, @class="Family">

So we've got some kind of yaml object with @ivars that looks to hold all the good stuff. Wouldn't it be nice if it just gave us Family and Kid objects! Yes it would be, but right now, since we're just irb-ing, YAML has no idea what a Family or Kid object looks like. Let's try this:

class Family; attr_accessor :name; end
class Kid; attr_accessor :name; end

YAML.load(File.read(test.yml))
#=> #<Family:0x576624 @name="McSpadden", @kids=[#<Kid:0x5768a4 @name="OshGosh">]>

That's what I'm talking about!

yaml-lab

I've found that when experimenting with new libraries it helps me to write a quick spec suite to test assumptions and understanding. In this vein, I've created a yaml-lab project on github with some of my experimentation. Feel free to clone it, fork it, whatever it. Here's the link yaml-lab on github.

That's all for now.

An Hour with Chef

Today I sat down and decided I would block out an hour to try out Chef, an ultrahip, super buzzed "systems integration framework." I really don't have an immediate need for Chef (well at least not that I know of yet!) but I love the idea of managing servers "by writing code, not by running commands" and it's all open source, Ruby goodness under the sheets, so I thought I'd give it a whirl.

I install the gem and head over to the "Configuring Chef" page. Right away I'm informed that working with Mac OS X probably is NOT going to go well out of the box. I do a few google searches and see there are a couple of Mac OS X cookbooks out there, but for this exercise, I decide to stay as close to official Opscode supported code as I can, so I dive in.

I get my ~/solo.rb and ~/chef.json setup per the instructions and now it's time to run chef-solo.

mark-mcspaddens-computer:~ mark$ sudo chef-solo -c ~/solo.rb -j ~/chef.json -r http://s3.amazonaws.com/chef-solo/bootstrap-latest.tar.gz
Password:
[Sun, 16 Aug 2009 16:05:47 -0500] INFO: Starting Chef Solo Run
/tmp/chef-solo/cookbooks/ruby/recipes/default.rb:45:in `from_file': undefined method `each' for nil:NilClass (NoMethodError)
from /usr/local/lib/ruby/gems/1.8/gems/chef-0.7.8/lib/chef/cookbook.rb:139:in `load_recipe'
from /usr/local/lib/ruby/gems/1.8/gems/chef-0.7.8/lib/chef/recipe.rb:79:in `include_recipe'
from /usr/local/lib/ruby/gems/1.8/gems/chef-0.7.8/lib/chef/recipe.rb:64:in `each'
from /usr/local/lib/ruby/gems/1.8/gems/chef-0.7.8/lib/chef/recipe.rb:64:in `include_recipe'
from /tmp/chef-solo/cookbooks/passenger_apache2/recipes/default.rb:26:in `from_file'
from /usr/local/lib/ruby/gems/1.8/gems/chef-0.7.8/lib/chef/cookbook.rb:139:in `load_recipe'
from /usr/local/lib/ruby/gems/1.8/gems/chef-0.7.8/lib/chef/recipe.rb:79:in `include_recipe'
from /usr/local/lib/ruby/gems/1.8/gems/chef-0.7.8/lib/chef/recipe.rb:64:in `each'
... 16 levels...
from /usr/local/lib/ruby/gems/1.8/gems/chef-0.7.8/lib/chef/application.rb:57:in `run'
from /usr/local/lib/ruby/gems/1.8/gems/chef-0.7.8/bin/chef-solo:26
from /usr/local/bin/chef-solo:19:in `load'
from /usr/local/bin/chef-solo:19

Awesome. Well, I was warned. Since this is just an educational exercise for me, and decide to dig in and see what I can find. So I pull up /tmp/chef-solo in TextMate, and look at /tmp/chef-solo/cookbooks/ruby/recipes/default.rb. Ok. I see what's going on here. We're trying to install some ruby packages and my OS isn't listed the case statement. Well I'm a Ruby developer and know I already have all the Ruby libs I'll need, so let's just add an else case with an empty array.

# cookbooks/ruby/recipes/default.rb

# Line 24: Start of case
# Line 45: Add else case
extra_packages = case node[:platform]
when "ubuntu","debian"
%w{
ruby1.8
ruby1.8-dev
rdoc1.8
ri1.8
libopenssl-ruby
}
when "centos","redhat","fedora"
%w{
ruby-libs
ruby-devel
ruby-docs
ruby-ri
ruby-irb
ruby-rdoc
ruby-mode
}
else []
end

I'm pretty confident that will fix our error and not leave us without any libs we'll need, so let's try again this again, only this time we won't tell chef-solo to use the remote cookbook and by default it will use our local one instead. (Which is a big bonus...if I jack things up too bad, we just go back to the remote version.)

mark-mcspaddens-computer:~ mark$ sudo chef-solo -c ~/solo.rb -j ~/chef.json
Password:
[Sun, 16 Aug 2009 16:32:48 -0500] INFO: Starting Chef Solo Run
[Sun, 16 Aug 2009 16:32:54 -0500] INFO: Installing gem_package[stompserver] version 0.9.9
[Sun, 16 Aug 2009 16:33:03 -0500] INFO: Creating directory[/stompserver] at /stompserver
[Sun, 16 Aug 2009 16:33:03 -0500] INFO: Setting mode to 755 for directory[/stompserver]
[Sun, 16 Aug 2009 16:33:03 -0500] INFO: Creating directory[/stompserver/log] at /stompserver/log
[Sun, 16 Aug 2009 16:33:03 -0500] INFO: Setting mode to 755 for directory[/stompserver/log]
[Sun, 16 Aug 2009 16:33:03 -0500] INFO: Creating directory[/stompserver/log/main] at /stompserver/log/main
[Sun, 16 Aug 2009 16:33:03 -0500] INFO: Setting mode to 755 for directory[/stompserver/log/main]
[Sun, 16 Aug 2009 16:33:03 -0500] INFO: Creating template[/stompserver/run] at /stompserver/run
[Sun, 16 Aug 2009 16:33:03 -0500] INFO: Setting mode to 755 for template[/stompserver/run]
[Sun, 16 Aug 2009 16:33:03 -0500] INFO: Creating template[/stompserver/log/run] at /stompserver/log/run
[Sun, 16 Aug 2009 16:33:03 -0500] INFO: Setting mode to 755 for template[/stompserver/log/run]
[Sun, 16 Aug 2009 16:33:03 -0500] INFO: Creating a symbolic link from -> /etc/init.d/stompserver for link[/etc/init.d/stompserver]
[Sun, 16 Aug 2009 16:33:03 -0500] INFO: Creating a symbolic link from /stompserver -> /stompserver for link[/stompserver]
[Sun, 16 Aug 2009 16:33:03 -0500] ERROR: service[stompserver] (/tmp/chef-solo/cookbooks/runit/definitions/runit_service.rb line 65) had an error:
No such file or directory - /etc/init.d/stompserver status

Ok...something's going down with stompserver. Quick 'gem list' shows I have the gem. Let's see if the stompserver command works.

mark-mcspaddens-computer:~ mark$ stompserver -h
Usage: stompserver [options]
-C, --config=CONFIGFILE Configuration File (default: stompserver.conf)
-p, --port=PORT Change the port (default: 61613)
-b, --host=ADDR Change the host (default: localhost)
-q, --queuetype=QUEUETYPE Queue type (memory|dbm|activerecord|file) (default: memory)
-w, --working_dir=DIR Change the working directory (default: current directory)
-s, --storage=DIR Change the storage directory (default: .stompserver, relative to working_dir)
-d, --debug Turn on debug messages
-a, --auth Require client authorization
-c, --checkpoint=SECONDS Time between checkpointing the queues in seconds (default: 0)
-h, --help Show this message
mark-mcspaddens-computer:~ mark$ which stompserver
/usr/local/bin/stompserver

Ok I have stompserver, but I'm not getting a link into /etc/init.d/stompserver. So I hack around with trying to pass this directory into the runit_service command in the stompserver default recipe. After a few unsuccessful tries, resort to my old caveman ways and run a command:

sudo ln -s /usr/local/bin/stompserver /etc/init.d/stompserver

Time to run chef-solo again...it spins for a while...and spins for a long while...so I decide to investigate. I know the next command we're trying to hit is "/etc/init.d/stompserver status" So I run that in another Terminal and get:

mark-mcspaddens-computer:~ mark$ /etc/init.d/stompserver status
status
MemoryQueue initialized
TopicManager initialized
QueueManager initialized
Stomp protocol handler starting on 127.0.0.1 port 61613
/usr/local/lib/ruby/gems/1.8/gems/eventmachine-0.12.0/lib/eventmachine.rb:500:in `start_tcp_server': no acceptor (RuntimeError)
from /usr/local/lib/ruby/gems/1.8/gems/eventmachine-0.12.0/lib/eventmachine.rb:500:in `start_server'
from /usr/local/lib/ruby/gems/1.8/gems/stompserver-0.9.9/bin/stompserver:34
from /usr/local/lib/ruby/gems/1.8/gems/eventmachine-0.12.0/lib/eventmachine.rb:224:in `call'
from /usr/local/lib/ruby/gems/1.8/gems/eventmachine-0.12.0/lib/eventmachine.rb:224:in `run_machine'
from /usr/local/lib/ruby/gems/1.8/gems/eventmachine-0.12.0/lib/eventmachine.rb:224:in `run'
from /usr/local/lib/ruby/gems/1.8/gems/stompserver-0.9.9/bin/stompserver:17
from /etc/init.d/stompserver:19:in `load'
from /etc/init.d/stompserver:19

[NOTE: After the steps that follow, I realize I probably got this error because chef-solo was still running while I tried it. But it's still always fun to see things step by step, so I'll include my next steps even through they're probably not necessary.]

Super. I'm waaaayyyy past the "not running commands" so I do "sudo gem install eventmachine" and it upgrades me from 0.12.0 to 0.12.8. I kill the original chef-solo command (which is still just hanging) and next, I see if these acts have appeased stompserver.

mark-mcspaddens-computer:~ mark$ /etc/init.d/stompserver status
status
MemoryQueue initialized
TopicManager initialized
QueueManager initialized
Stomp protocol handler starting on 127.0.0.1 port 61613

This sits there for a while, but no errors, and since we're trying to run some kind of server here, I take no news as good news. I kill off the stompserver and decide it's time to try chef-solo again. And it hangs. But I've got an idea.

In one terminal I do "sudo /etc/init.d/stompserver status" and after that is rolling I open a different Terminal and run chef-solo. Looks like we're getting somewhere.

Sun, 16 Aug 2009 17:13:33 -0500] INFO: Starting Chef Solo Run
[Sun, 16 Aug 2009 17:13:34 -0500] INFO: Creating a symbolic link from -> /etc/init.d/stompserver for link[/etc/init.d/stompserver]
[Sun, 16 Aug 2009 17:13:34 -0500] INFO: Creating a symbolic link from /stompserver -> /stompserver for link[/stompserver]
[Sun, 16 Aug 2009 17:13:39 -0500] INFO: Installing package[apache2] version 2.2.10

So I've got stompserver behind me, but this Apache install is taking a bit of time...and then I get.

[Sun, 16 Aug 2009 17:18:08 -0500] ERROR: service[apache2] (/tmp/chef-solo/cookbooks/apache2/recipes/default.rb line 30) had an error:
wrong number of arguments (0 for 1)

Ok. Let's open up the apache2 cookbook and see what's up. I open up /tmp/chef-solo/cookbooks/apache2/recipes/default.rb and start trying a few ways on including "mac_os_x" and my specific system setup in into a few of the case statements, but after about 5 minutes I've still got the same error.

----

And my hour is up*. Kind of a bummer...but not really. To me, this is really kind of cool. Sure I would have loved to get my chef server configured, but getting to crack open a few recipes and even the chef source itself is a really cool exercise.

Next time I go Chefing, I'll probably start with one of the Mac OS X cookbooks out there or fire up my Ubuntu laptop that normally sits idle in the office. Honestly, I would love to see an Opscode endorsed/supported/linked_to Mac OS X cookbook, it would have given me the confidence to start with one of those today. (But then again I may have missed out on some good code spelunking.)

Overall I enjoyed my hour with Chef and look forward to trying this all again at a future date. I'm very surprised at how straight forward the framework seems to be and how easy it was to jump in and get dirty with it.

All this talk about Chef, and cookbooks, and recipes has me hungry. Time for a snack! :)


* A younger less disciplined me would have kept hacking until I got it working, but that really wasn't the point of the exercise. Also, the timestamps will show I went a little longer than an hour. My brother called and we chatted for a bit. Family > Code...most of the time.