Improve Test-kitchen Performance

At my current gig, we've automated our cookbook testing with test-kitchen and integrated it into Jenkins.  This was all fine and good until we started to get concerned with how long our testing was taking, given that many of our .kitchen.yml files include multiple platforms and multiple test suites.  Because of this, some of our tests have as many as 8 systems to build so we can test all of the variations, and a single change would result in a 90 minute feedback loop.  That's WAY too long.

So I started doing some investigating into what was taking so long and I discovered that our Vagrant systems were swapping heavily during Chef runs.  That's when I discovered that Vagrant uses 256MB of memory as the default setting for it's instances.  That lead me to add in the following parameter to all of our .kitchen.yml files:

- name: centos-6.5
  driver_config:
    box: centos-6.5
    box_url: http://imagesource.acme.com/centos-6.5.box
    customize:
      memory: 1024

This simple change in the .kitchen.yml file decreased 90 minute test runs to 25 minutes!

Command-line Kung Fu

I recently stumbled on an article on Lifehacker that suggested a way to learn Linux commands in-line with your daily systems administration.  Basically, it calls for adding a string of commands to your .bashrc file that randomly selects a command from various bin directories and executes a whatis on them.

I thought it was brilliant, but when I went to try it I was bummed to find out that the shuf command is not shipped with the base distribution of CentOS, which is the primary OS I support.  Because of this, I decided to spin my own version of the hack that will work on CentOS.

# RANDOM COMMAND-LINE KNOWLEDGE

# List of bin directories that include commands you'd like to learn
binDirs='/bin /usr/bin /usr/sbin /sbin'

# Count the number of commands in $binDirs and randomly select a number in the range
randomNum=$(expr $RANDOM % $(ls $binDirs | wc -l))

# Based on the selected $randNum, select the corresponding command
randomCmd=$(ls $binDirs | head -${randomNum} | tail -1)

# Lookup the command with whatis and display the results
echo "Did you know that:"
whatis $randomCmd | sed 's/^/\t/g'

The hack isn't perfect because not all commands have an entry in the whatis database.  When this happens, you will see a response similar to this:

Did you know that:

        numastat: nothing appropriate

But, this doesn't happen all that often, and with this hack, I've discovered some awesome commands like watch.

Did you know that:
        watch                (1)  - execute a program periodically, showing output fullscreen