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Cookbook Components – Attributes

Hands-On Lab

 

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Training Architect

Length

01:00:00

Difficulty

Intermediate

In this lab we will install the ChefDK tools on a server. We will need to make sure Docker is working, then ensure that Git is installed and has some basic configuration. Then we'll gain an understanding of Local Cookbook Development by creating a cookbook that uses a custom attribute to install a package. At the end of this hands-on lab, we will have installed and configured ChefDK tools, developed cookbooks, and tested them with docker and kitchen commands.

What are Hands-On Labs?

Hands-On Labs are scenario-based learning environments where learners can practice without consequences. Don't compromise a system or waste money on expensive downloads. Practice real-world skills without the real-world risk, no assembly required.

Cookbook Components - Attributes

Introduction

In this lab we will install the ChefDK tools on a server. We will need to make sure Docker is working, then ensure that Git is installed and has some basic configuration.

Then we'll gain an understanding of Local Cookbook Development by creating a cookbook that uses a custom attribute to install a package.

At the end of this hands-on lab, we will have installed and configured ChefDK tools, developed cookbooks, and tested them with docker and kitchen commands.

Instructions

We have a few tasks that need to be completed:

  1. Set up the environment for use with the rest of the tasks by installing Chef, Docker, Git and the Chef gem for Docker:
    • Install version 2.4.17 of the ChefDK tools.
    • Install Docker CE and all that it requires, start it up, then make it start at boot:
      • Modify our group membership so we don't need to run sudo all the time.
    • Install Git, and configure a name, email, and default editor.
    • Install the gem allowing Kitchen and Docker to work together.
    • Set SELinux to allow us to work through the rest of the steps.
  2. Create a cookbook called la_attributes.
  3. Create an attribute called default.
  4. Edit our kitchen.yml:
    • Change our driver name so that we're using Docker
    • Make it run in a privileged manner
    • Set it up so that we don't have to use sudo
    • Add a provisioner name and version
    • Remove any platforms so that it's just set to work on CentOS 7
  5. Configure the attribute we created earlier:
    • Add a default attribute of app and language, with a value of perl.
  6. Edit our recipe so that our attribute gets installed.
  7. Verify that the cookbook works
  8. Log into the Kitchen instance and test for whether or not the Perl language got installed.
  9. Clean up the environment.

Logging In

Using the credentials provided in the hands-on lab page, log into the server as cloud_user and we can get going.

On the Provided Server, Install Version 2.4.17 of the ChefDK Tools

We need to download the correct version of ChefDK, which is 2.4.17. In a command line, run:

wget https://packages.chef.io/files/stable/chefdk/2.4.17/el/7/chefdk-2.4.17-1.el7.x86_64.rpm

Now install it:

sudo rpm -ivh chefdk-2.4.17-1.el7.x86_64.rpm

Once it's installed, we need to make sure Chef uses the correct system locations for things:

echo 'eval "$(chef shell-init bash)"' >> ~/.bash_profile
source ~/.bash_profile

Now check to see if it worked with which ruby, and we should see /opt/chefdk/embedded/bin/ruby get returned.

Install What docker-ce Requires on This Server

We need Docker on our workstation, so we will need to install the yum-utils, add the Docker repository, and install Docker.

sudo yum -y install yum-utils
sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
sudo yum -y install docker-ce

Now let's set Docker to start now, and on system boot:

sudo systemctl start docker
sudo systemctl enable docker

We should also set your user to be able to use Docker without using the sudo command. Once we've done this, we have to log out and back in again:

sudo usermod -aG docker $USER
exit

Use SSH to get back in again, and check to make sure Docker is running:

docker ps

If we can do that without prefacing it with sudo, we're ready to continue.

Install Git and Set Some Global Defaults for Our User, Email Address, and Editor

When we use Kitchen, later in the lab, we need Git to be installed and set up with some basic information. These commands will make that happen:

Install it:

sudo yum -y install git

Configure some Git basics, like the username, email address, and a default text editor:

git config --global user.name "USERNAME"
git config --global user.email "YOUREMAIL@DOMAIN.COM"
git config --global core.editor vim

Note: We can use fake email information, since we don't actually use it for this lab. It just needs to be set or we will get errors later.

Install the Gem Required for Using Docker with the Test Kitchen

Docker requires a gem for this all to work. Install it with this:

gem install kitchen-docker

Update SELinux to Be Permissive

To perform the tasks properly you should change SELinux so that it is permissive:

sudo setenforce permissive

We should also /etc/selinux/config and change things to permissive there too:

sudo vim /etc/selinux/config

Change the SELINUX line from SELINUX=enforcing to SELINUX=permissive

Create a Cookbook for Use with These Tasks, and Call it la_attributes

Create the cookbook with this command:

chef generate cookbook la_attributes

Now get into the newly created directory:

cd la_attributes

Generate an Attribute Called default

Now we can generate an attributes, called default:

chef generate attribute default

We'll see an attibutes directory, if we run ls.

Edit Our Kitchen File

We need to change some things in kitchen.yml, so let's edit it:

vim .kitchen.yml

In the top section, we're going to replace vagrant with docker, and add some things. When we're done, that top section should look like this:

---
driver:
  name: docker
  privileged: true
  use_sudo: false

Remember that this is YAML, so we need to make sure we have the right number of spaces in spots. Those lines under driver are all indented two spaces.

Down in the provisioner section, we need to add a name and version. It should look like this when we're done:

provisioner:
  name: chef_zero
  # You may wish to disable always updating cookbooks in CI or other testing environments.
  # For example:
  #   always_update_cookbooks: <%= !ENV['CI'] %>
  always_update_cookbooks: true
  product_name: "chef"
  product_version: "13.8.5"

We're on a CentOS machine, so we need to get rid of ubuntu from the file. Just delete (or comment out) the line in the platforms section that reads:

  - name: ubuntu-16.04

That's it for kitchen.yml edits. Write and quit, so that we can get back to the command prompt.

Configure the Attribute We Created Earlier

Edit the attributes/default.rb file:

vim attributes/default.rb

Add the specific attributes:

default['app']['language'] = 'perl'

Edit Our Recipe

We need to get the perl package installed, the one we referred to back in the attribute, so add this text to the end of the ./recipes/default.rd file:

package node['app']['language'] do
  action :install
end

Verify That the Cookbooks Work

Use the kitchen verify command to ensure the cookbook works. We should see a line in the output that says yum_package[perl] action install.

Log into the Kitchen Instance to Check That Perl Got Installed

We can log in with kitchen login. Once we're in, we'll run perl -v. If we get a version number, then we know Perl has been installed.

Clean up the Environment

To clean up after ourselves, we just use the kitchen destroy command.

Conclusion

Well, we've done what we set out to do. We took a fresh server, built some framework, and were able to develop a simple cookbook that installed a package with a custom attribute. Congratulations!