DevOps Classroom Series – 19/June/2021

Changing Convergence using Chef-Client Supermarket cookbook

• Add the following to the attributes file with your time interval

default['chef_client']['interval'] = 60

• Add the following to the run_list or default.rb

include_recipe 'chef-client::default'

Attribute Precedence

• In chef we can define attributes
  • attribute file

  default['qt_tomcat']['java_package'] = 'openjdk_8_jdk'
  

  • recipe

  node.default['qt_tomcat']['java_package'] = 'openjdk_8_jdk'
  

  • environments

  default_attributes( {'qt_tomcat' => {'java_package' => 'openjdk_8_jdk'}})
  

  • roles

  default_attributes( {'qt_tomcat' => {'java_package' => 'openjdk_8_jdk'}})
  

• Attributes have types
  • default
  • force_default
  • normal
  • override
  • force_override
  • automatic
• If we define the attribute at only one location (attributes, recipes, environments) then the attribute will be applied as expected
• But if we define the attribute with different values at different locations, then chef has weights associated in the combination of location & type.
• the attribute with higher weight will be applied
• Environments and roles have only two possible attribute types
  • default
  • override
• Automatic type is only for the attributes collected by chef client by running ohai tool

Data bags

• Data Bags are global variables which are stored as JSON data. Data bags can be used for storing sensitive content as the data bags support encryption and decryption
• Refer Here for the official docs
• Lets use a chef data bag to store sensitive
• Create a data bag using knife command

knife data bag create qtsensitive

• create a folder structure in chef-repo

chef-repo
----> data_bags
     ----> qtsensitive
           ----> passwords.json
----> cookbooks
----> environments
-----> roles

• The passwords.json file content

{
 "id": "passwords",
 "tomcat_password": "india@123",
 "mysql_password": "rootinqt123",
 "postgres_password": "rootinqt123"
}

• Lets upload this data bag item to chef server

knife data bag from file qtsensitive <path to passwords.json>

• Upload the data bag with secret text

knife data bag from file qtsensitive <path to passwords.json> --secret <secret text>

• But the local file in chef-repo is not encrypted to do that use

knife data bag from file qtsensitive <path to passwords.json> --secret <secret text> --local-mode

• Now lets see how to decrypt the encrypted password in the chef recipes
• Refer Here for the chef-repo used in the class room

Chef Server Install

• Refer Here for the steps

• Refer Here for the pre-requisites

• Commands used in the class to install chef server

mv chef-server-core_14.4.4-1_amd64.deb /tmp/
sudo dpkg -i /tmp/chef-server-core_14.4.4-1_amd64.deb
sudo chef-server-ctl reconfigure
sudo chef-server-ctl user-create qtdevops qt Devops qtdevops@gmail.com 'india123' --filename /home/ubuntu/qtdevops.pem
sudo chef-server-ctl org-create qthought 'QT Devops' --association_user qtdevops --filename /home/ubuntu/qthought-validator.pem
sudo chef-server-ctl install chef-manage
sudo chef-server-ctl reconfigure
sudo chef-manage-ctl reconfigure