DevOps Classroom Series – 10/Nov/2021

Notifications

• A resource may listen to another resource and then take action if the state of the resource being listened changes

file '/var/www/html/info.php' do
    content '<h1> hello </h1>'
end

service 'apache2' do
  action :nothing
  subscribes :restart, 'file[/var/www/html/info.php]', :immediately
end

file '/tmp/apache2' do
  action :nothing
  subscribes :touch, 'file[/var/www/html/info.php]', :immediately
end

Activity: Installing tomcat9 on ubuntu 20.04

• Refer Here for the manual steps
• Lets execute manual steps on the machine created using test kitchen
• Create a new cookbook tomcat9
• Initially lets automate till tomcat installation and enabling tomcat service
• Improvements:
  • Writing all the resources in one recipe is not a good idea. So lets create different recipes.
  • Lets start by using attributes
• Best Practices:
  • default.rb in recipes should just have resources to fail if they are running on unsupported platform or platform family and it should call other recipes to automate the deployment
• Recipe name => Generally recipe name is <cookbook-name>::<recipe-name-with-out-extension>. If we donot pass recipe name chef will assume it to be default <cookbook-name> => <cookbook-name>::default
• Lets generate a recipe for java installation
• Attributes so far

if platform?('ubuntu')
  default['tomcat9']['java_package'] = 'openjdk-11-jdk'
end

• recipe => java

#
# Cookbook:: tomcat9
# Recipe:: java
#
# Copyright:: 2021, The Authors, All Rights Reserved.

apt_update 'update ubuntu packages' do
  ignore_failure true
  action :update
  only_if { platform?('ubuntu') }
end

package node['tomcat9']['java_package'] do
  action :install
end

• recipe => default

#
# Cookbook:: tomcat9
# Recipe:: default
#
# Copyright:: 2021, The Authors, All Rights Reserved.

include_recipe 'tomcat9::java'

• Refer Here for the changes done
• Now lets try to converge to check if the java 11 is getting installed or not
  • kitchen converge
  • login & check for java installation
• Next step to be automated

sudo useradd -m -U -d /opt/tomcat -s /bin/false tomcat

 -m, --create-home
  -d, --home-dir /opt/tomcat
 -U, --user-group   create a group with the same name as the user => tomcat

 -s, --shell SHELL             login shell of the new account /bin/false

• Refer Here for the user resource
• For this lets create a new recipe configure
• Refer Here for the changes done
• Now add this recipe to default.rb in recipes

include_recipe 'tomcat9::java'
include_recipe 'tomcat9::configure'

• Fixed the group not existing issue and added configure to be included from default in this changeset Refer Here
• Exercise: Try to automate the steps which we have done for ubuntu in this cookbook to make it work for centos7 following the documentation Refer Here