Ansible, Puppet, and Chef

Ansible

Ansible is a powerful open platform for automating configurations, managing deployments, and orchestrating tasks. Unlike other configuration management systems that often use complex agents, Ansible is powered by agentless architecture. That is, to perform its tasks, it only requires SSH access and Python on managed nodes. What could be simpler?

Ansible configurations are described in YAML format in files called Playbooks. These Playbooks allow you to declaratively describe the state of the system, eliminating the need to execute complex command scripts. The point is that you can tell Ansible what the final result is needed, and it takes care of all the details rough work.

With Ansible you can:

• Automatically deploy applications.

• Manage services, install and update packages.

• Integrate with cloud platforms like AWS, Microsoft Azure, and Google Cloud.

• Orchestrate virtual machines and containers, including Kubernetes and Docker.

• Manage users and access rights.

• Configure network devices from various manufacturers.

Ansible has idempotency – the ability to run the same Playbook many times, and changes will only be applied in case of deviations from the desired state.

Puppet

Puppet already using the model client-server, where the Puppet Master management server interacts with agents installed on managed nodes. The main feature of Puppet is its ability to declaratively describe the state of system resources using its configuration language – Puppet DSL.

For example, you can manage files and their contents this way:

file { '/etc/nginx/nginx.conf':
  ensure  => 'file',
  owner   => 'root',
  group   => 'root',
  mode    => '0644',
  content => template('nginx/nginx.conf.erb'),
  require => Package['nginx'],
}

This description is then compiled into a directory that contains all the resources and their dependencies needed to achieve the desired system state.

It is also worth noting that Puppet, like Ansible, supports the concept of idempotency; it is achieved due to the fact that Puppet checks the current state of a resource before applying changes and actively makes changes only if necessary.

Puppet features:

• Modularity: It is possible to create modules that can be reused in different projects and environments.

• Hiera: A configuration data management tool that allows you to separate data from code.

• Factor: A utility that collects system information such as OS, IP addresses, RAM and other facts, which can then be used in configurations.

Chef

Chef is a powerful automation platform that lets you manage infrastructure as code using Ruby. That is, the configurations of servers, devices, and entire clouds are described in the form of code, which can then be versioned, tested and reused in different environments with a high degree of consistency.

Main components of Chef:

• Chef Server: A central server where all recipes, cookbooks, and policies are stored, as well as state information for each managed node.

• Chef Client: Installed on each managed node and is responsible for applying the configurations set on the server.

• Chef Workstation: A place where they create and test their cookboxes and recipes before distributing them through the Chef Server.

For example, let's set up a server with Chef, where the goal is to install and configure the Nginx web server on a node running Ubuntu OS. Let's skip all the installation points, everything is quite simple there.

In Chef Workstation we create a new cookbook that will contain all the necessary instructions and resources:

chef generate cookbook nginx_cookbook

The command will create a directory structure for a new cookbook called nginx_cookbook.

Next, go to the cookbook directory and create a recipe that will manage the Nginx installation. Open the file recipes/default.rb and write there:

# установка пакета Nginx
package 'nginx' do
  action :install
end

# управление службой Nginx
service 'nginx' do
  supports status: true, restart: true, reload: true
  action [:enable, :start]
end

# создание и публикация основной страницы Nginx
file '/usr/share/nginx/html/index.html' do
  content '<html>
  <head><title>Welcome to Chef managed Nginx!</title></head>
  <body><h1>Hello from Chef managed Nginx!</h1></body>
  </html>'
  mode '0644'
  owner 'www-data'
  group 'www-data'
  notifies :reload, 'service[nginx]', :immediately
end

Upload the cookbook to the Chef server for further distribution:

knife cookbook upload nginx_cookbook

Let's add the recipe from the cookbook to the run list for the target node via Chef Server using the command knife or via Web UI. After this, Chef Client installed on the target node will be able to apply the settings:

knife node run_list add NODE_NAME 'recipe[nginx_cookbook]'

Launch Chef Client on the node to apply the settings:

sudo chef-client

Let's compare these tools in the table

In conclusion, I remind you of the open lesson on configuration management and infrastructure stabilization. The lecture will discuss methods and tools for automating configuration management processes, change control and ensuring system integrity. Join us follow the link to register.