DevOps Classroom Series – 17/Apr/2020

Recipe DSL (Domain Specific Language)

• In chef we write recipes, and recipes are .rb (ruby) files
• To work on chef you donot need to know whole ruby, but you can use any thing in ruby.

file '/tmp/test.txt' do
  action :create
end

Write a chef cookbook to install tomcat server

• Documentation as reference
• Create a chef cookbook

chef generate cookbook -b tomcat

• Find out manual commands to install tomcat on ubuntu

sudo apt-get update
sudo apt-get install tomcat8 -y

• These steps are specific for ubuntu, so let me create a new recipe for ubuntu

chef generate recipe --help
chef generate recipe . tomcat_ubuntu

• Every recipe will have a naming format <cookbookname>::<recipename>
  • in tomcat cookbook tomcat_ubuntu recipe name tomcat::tomcat_ubuntu
  • Writing default or directly writing cookbookname is same tomcat is equal to tomcat::default
• Lets try to automate the below commands and write them in tomcat_ubuntu recipe

sudo apt-get update
sudo apt-get install tomcat8 -y

• Now add the resources in tomcat_ubuntu recipe

#
# Cookbook:: .
# Recipe:: tomcat_ubuntu
#
# Copyright:: 2020, The Authors, All Rights Reserved.

apt_update 'update' do
    ignore_failure true
    action :update
end

apt_package 'tomcat8' do
    action :install
end

• Now make changes in the run_list in the kitchen.yaml file
• Now we want to install tomcat on centos using the same cookbook
• Manual commands are

sudo yum install tomcat -y
sudo service tomcat start

• Create a new recipe tomcat_centos

#
# Cookbook:: .
# Recipe:: tomcat_centos
#
# Copyright:: 2020, The Authors, All Rights Reserved.

yum_package 'tomcat' do
    action :install
end

service 'tomcat' do
    action :start
end

• Now i want to run recipe tomcat_ubuntu when the machine is ubuntu and recipe tomcat_centos when the machine is centos
• In chef we have a software called as ohai, which collects information about nodes and gives it to the chef server
• Note: Before next class bootstrap two nodes one ubuntu and one chef to manage.chef.io
• Now in the default.rb file in recipes i have written a simple condition to call the necessary recipe

#
# Cookbook:: tomcat
# Recipe:: default
#
# Copyright:: 2020, The Authors, All Rights Reserved.

if node['platform_family'] == 'rhel' 
    include_recipe 'tomcat::tomcat_centos'
elsif node['platform_family'] == 'debian'
    include_recipe 'tomcat::tomcat_ubuntu'
end

• And also i have changed kitchen.yaml file to include both platforms

---
driver:
  name: ec2
  aws_ssh_key_id: chef
  region: us-west-2
  availability_zone: us-west-2b
  subnet_id: subnet-89fb32ee
  instance_type: t2.micro
  image_id: 'ami-0bc06212a56393ee1'
  security_group_ids: ["sg-0fde1a94ae5592488"]

## The forwarded_port port feature lets you connect to ports on the VM guest via
## localhost on the host.
## see also: https://www.vagrantup.com/docs/networking/forwarded_ports.html

#  network:
#    - ["forwarded_port", {guest: 80, host: 8080}]

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 and product_version specifies a specific Chef product and version to install.
  ## see the Chef documentation for more details: https://docs.chef.io/config_yml_kitchen.html
  #  product_name: chef
  #  product_version: 15

verifier:
  name: inspec

transport:
  ssh_key: "./chef.pem"
  connection_timeout: 10
  connection_retries: 3
  username: centos

platforms:
  - name: ubuntu-18.04
    driver:
      image_id: 'ami-0d1cd67c26f5fca19'
    transport:
      username: ubuntu
  - name: centos-7

suites:
  - name: default
    run_list:
      - recipe[tomcat::default]
    verifier:
      inspec_tests:
        - test/integration/default
    attributes:

Exercise: Now try this approach for install apache server.

1. Create a cookbook called as apache
2. Ensure your kitchen has two platforms
3. manual steps are given below

centos:

sudo yum install httpd
sudo service httpd start -y

ubuntu:

sudo apt-get update
sudo apt-get install apache2 -y