DevOps Classroom Series – 03/Nov/2021

Just enough Ruby for Chef

• Refer Here for the official docs from chef
• Local variables

x = 1 # number
y = 'hello' # string
z =  "hai" # string

• Embed a ruby variable in a string

topic = 'chef'
'Hello all, Welcome to #{topic}'
"Hello all, Welcome to #{topic}"

• True and false (boolean)
• Arrays
• White space Arrays: This is shortcut for creating arrays without quotes and commas
• Hash:
• Conditional Statement using if else:

if <condition>
    # if block
elsif <condition>
    # else if block
else
    # else block
end

• Looping using each

%w(redhat ubuntu).each do |osname|
  puts(osname)
end

• Other useful statements

Chef contd..

• Now lets try to apply whitespace array to array for package names in the apache_phpinfo cookbook Refer Here for the change set
• Now apply the kitchen convergence and verify if everything works or not
• Now our aim is to ensure this cookbook works for redhat instances also. The manual steps are

sudo yum install httpd -y
sudo systemctl enable httpd
sudo systemctl start httpd
sudo yum install  php php-mysql php-fpm -y
echo "<?php phpinfo(); ?>" | sudo tee /var/www/html/info.php
sudo systemctl restart httpd

• When we want to run the recipe on different distributions of linux we should have a way to identify the way to find the information about the node on which recipe is executing.
• For doing this in chef there is tool called as ohai which gets installed on the node and informs the chef server about the details of the node