Chef - Configuration Management

Imperative vs Declarative Approach

• Imperative == Shell Script
• Declarative == Chef

Push based vs Pull Based Deployments

• Push Based = Ansible, SaltStack

  • Master server pushes the configurations and softwares to the individual servers

• Pull Based = Chef, Puppet

  • Individual servers establishes connection with the master server and downloads, installs their required updates whenever needed.
  • Configuration pull is initiated by agent at regular intervals

Chef - Ruby based IT automation tool

Chef Deployment Model

• Server-Client - Production use cases

  • Master Server can only be Linux
  • Client/Nodes can be Windows or Linux

• Chef Zero - Development, Testing, POC

user 'username' do
    action: create
end

Install and configure httpd webserver

### Web Server Installation
package 'httpd' do
     action :install
end

### Web Server File Confirguration
file '/var/www/html/index.html' do
   content "Getting started with Chef\n"
   action :create
end

### Web Server Service Startup
service 'httpd' do
    action :start
end

Chef Components

1. Chef-Workstation
2. Chef Server
3. Chef-Client/Node

Chef Workstation

• Local Development Platform used to create, test and apply chef codes.
• Can be a local desktop or laptop with Chef DK (or) Chef Development Kit installed on it.
• Can be used as Chef Zero for developing, testing and validating chef codes before promoting to production.

Chef Server

• It is a node which has Chef server installed and configured.
• It manages chef code in a centralized location.
• Chef Workstation pushes the cookbooks to the Chef Server.

Chef Client

• The client node connects to the chef server and pulls the required configuration files and configures them locally.