If you are trying to use rrdtool on an Engine Yard instance and your Ruby version is 1.8.7, you might get this error:

irb(main):001:0> require 'RRD'
LoadError: librrd.so.2: cannot open shared object file: No such file or directory - /usr/lib/ruby/site_ruby/1.8/i686-linux/RRD.so
from /usr/lib/ruby/site_ruby/1.8/i686-linux/RRD.so
from (irb):1
from :0

It’s sort of confusing because it looks like RRD.so doesn’t exist, but it does:

~ $ ls /usr/lib/ruby/site_ruby/1.8/i686-linux/RRD.so
/usr/lib/ruby/site_ruby/1.8/i686-linux/RRD.so

What is happening is that RRD.so is linked to a missing shared library:

/usr/lib/ruby/site_ruby/1.8/i686-linux $ ldd -v RRD.so
linux-gate.so.1 => (0xb7f23000)
libruby18.so.1.8 => /usr/lib/libruby18.so.1.8 (0xb7e3f000)
librrd.so.2 => not found
libdl.so.2 => /lib/libdl.so.2 (0xb7e34000)
libcrypt.so.1 => /lib/libcrypt.so.1 (0xb7e05000)
libm.so.6 => /lib/libm.so.6 (0xb7ddf000)
libc.so.6 => /lib/libc.so.6 (0xb7cab000)
librt.so.1 => /lib/librt.so.1 (0xb7ca2000)
/lib/ld-linux.so.2 (0x80000000)
libpthread.so.0 => /lib/libpthread.so.0 (0xb7c8a000)

Which brings up the question where does RRD.so come from?

~ $ equery belongs RRD.so
[ Searching for file(s) RRD.so in *... ]
net-analyzer/rrdtool-1.4.5 (/usr/lib/ruby/site_ruby/1.8/i686-linux/RRD.so)

However the package net-analyzer/rrdtool only provides librrd.so.4 not librrd.so.2:

~ $ equery belongs librrd.so
[ Searching for file(s) librrd.so in *... ]
net-analyzer/rrdtool-1.4.5 (/usr/lib/librrd.so -> librrd.so.4.1.4)

That seems mean that Engine Yard is pre-building the packages they provide and the current rrdtool package was built incorrectly.

I opened a support issue with Engine Yard about this and have been going back and forth with them about it. Finally I got this from them:

“It looks like there was an issue with compilation when we upgraded RRDTool to 1.4.5 on Ruby 1.8.7. If you need to use it, you shouldn’t have a problem with 1.9.2 or 1.9.3. As of right now, we’ll have to look into adding support on 1.8.7 but there’s no timeframe.”

A few days later that was followed up with:

“Moving forward, our developers are going to focus on more pressing issues right now than edge cases.”

“I will make sure that we Roadmap this since we are still supporting 1.8.7 but no idea on a time frame.”

So the rrdtool package they provide is broken for Ruby 1.8.7 and they probably won’t fix it any time soon.

The only workaround I could think of was to have a chef recipe to remove the offending RRD.so file and then install the librrd gem which will build a RRD.so file that is useable. I tested this on a staging environment and everything worked as expected.

However, rather than deploying this workaround we decided to go in a different direction to capture and report the metrics we where interested in for our application.