Thursday, April 14, 2016

Chef-Kitchen Do it simply..


If you are from agile background you would be already aware about the importance of testing your code as you develop. As DevOps SCM tools are maturing where we try to have our complete infrastructure as code it becomes a dire necessity to have our infrastructure code to be tested as well. In this blog I'll showcase how I'm using the testing capability of Chef to test our Chef code.

Prerequisites

This blog assumes that you have a basic understanding of Chef, Docker, Git and Vagrant. This blog is written in consideration with centos as platform. You can follow same procedure for ubuntu with some basic changes.

Setup Kitchen
Clone from our github repository to spin up a vagrant with kitchen and other chef tools.


  • Go to testkitchen directory.  

$ cd  Chef/centos/testkitchen


This directory includes a Vagrantfile, a cookbook and a knife.rb file.


  • View vagrantfile for provisioning.
This Vagrantfile have some basic vagrant provisioning with shell.
$ cat Vagrantfile

This file provision your vagrant using shell.


As this block contains a lot of stuff. FIrstly this need two rpm files to be placed in current directory (i.e. vagrant/chef/centos/testkitchen). Download these rpm using following commands. This vagrantfile uses centos/7 as base box.

$ wget ftp://195.220.108.108/linux/centos/7.2.1511/extras/x86_64/Packages/epel-release-7-5.noarch.rpm

Next in this block we are installing docker and rvm to manage our ruby version to 2.2.4.

  • Spin Up Vagrant box
$ vagrant up

This will perform everything for you. And creates a running vagrant with centos7 platform. Next login into this vagrant box using following command.

$ vagrant  ssh

Your testing environment is ready and you are all set to use kitchen to test and verify your cookbooks in different platforms using docker container.  

Test your first cookbook  

Change directory to /vagrant. /vagrant directory is shared between host and guest machine.

$ cd /vagrant

This cloned repo has its first cookbook “helloworld” in cookbooks folder. This cookbook creates a directory and place a hello.txt file in it.

Go to /vagrant folder and start using kitchen.
  • Initialize kitchen

$ kitchen init --driver=docker


This command initialize mandatory stuff to start with your kitchen. This creates  .kitchen.yml, chefignore file and a test folder.
.kitchen.yml file is the main configuration file for kitchen. This file contains mainly 4 blocks driver, provisioner, platforms and suites.
    • Driver:  This is the name of driver that is used to create new node for testing
    • Provisioner: This is the chef provisioner to simulate test, chef-zero and chef-solo are the options.
    • Platforms: This is the type of platform on which kitchen runs test eg. ubuntu-14.04 and centos-7.1
    • Suites: This is the collection of test suites with runlist and attributes.
       

Chefignore file determine which files to ignore when uploading cookbooks.
Test folder contains all test files running over the cookbooks.

  • Install required gems
Install required gems by using bundle. As your directory contains a Gemfile where gems are described with their specific version.  
$ bundle install

Then to verify run following command.

$ gem list kitchen
As this install two essential gems kitchen-docker and test-kitchen.

  • List all  your nodes.
$ bundle exec kitchen list
This command list all your nodes with last action performed on them.

Start kitchen cycle

  • Create your node using following command
$ bundle exec kitchen create

    • This command pulls image of docker if they are not present locally.
    • Install  openssh-server and other essential packages in newly created docker container.
if get “Kitchen is finished.” as final output. Now verify with kitchen list once again.


  • Converge your node
This step deploys your cookbook to newly created node. So let's tell kitchen which cookbook to run. Edit .kitchen.yml file and add recipe in runlist attribute of suits block.
Now run following command to converge your node.

$ bundle exec kitchen converge

    • Chef solo and dna.json got prepared and pushed into node /tmp/kitchen directory
    • This will put cookbook into the node and install chef by performing an Omnibus package installation.
    • Chef run initiated with information in .kitchen.yml file.
Verify again with kitchen list.

  • Login into node
$ bundle exec kitchen login  default-ubuntu-1404
&&
$ bundle exec kitchen login  default-centos
    • Login into node and manually verify /data directory and hello.txt file in it.

  • Verify your cookbook
Look into test directory structure.

As this directory contains “default” folder this is corresponding to your suit name i.e. default. Now create a directory structure to put files in particular location.

    • Use Bats to create test

$ mkdir -p test/integration/default/bats

Busser is the component which provides facility of testing in your node. Bats directory tells kitchen to which Busser runner plugin needs to be installed on the remote instance. In other words the bats directory name will cause Busser to installbusser-bats from RubyGems.

      • Write first test file.
$ vim  test/integration/default/bats/hellotest.bats

#!/usr/bin/env bats

@test "/data directory found in path" {
 run stat /data
 [ "$status" -eq 0 ]
}

@test "hello.txt file found in path" {
 run stat /data/hello.txt
 [ "$status" -eq 0 ]
}
      • Run kitchen verify

$ bundle exec kitchen verify

Now verify again with kitchen list, and see last action.

    • Use serverspec to create test
$ mkdir -p test/integration/default/serverspec

      • Write a test
$ vim  test/integration/default/serverspec/hellotest_spec.rb

require 'serverspec'

# Required by serverspec

set :backend, :exec

describe "file hello.txt status" do
 it "file hello.txt" do
   expect(file("/data/hello.txt")).to exist
 end
end

      • Run kitchen verify

$ bundle exec kitchen verify

Now verify again with kitchen list, and see last action.



  • Destroy your node
$ bundle exec kitchen destroy

This will destroy your node.

Kitchen test

$ bundle exec kitchen test

Kitchen test is an option to perform complete kitchen cycle with one command. This destroy existed nodes and then create, converge, verify node with your predefined suit in .kitchen.yml. And finally it destroy the node.

Now your cookbook is tested. So feel confident to use it.  

6 comments

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