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  • Chef Cookbook
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Chef Cookbook

Chef Cookbook

By : Marschall
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Chef Cookbook

Chef Cookbook

By: Marschall

Overview of this book

Chef is a configuration management tool that lets you automate your more cumbersome IT infrastructure processes and control a large network of computers (and virtual machines) from one master server. This book will help you solve everyday problems with your IT infrastructure with Chef. It will start with recipes that show you how to effectively manage your infrastructure and solve problems with users, applications, and automation. You will then come across a new testing framework, InSpec, to test any node in your infrastructure. Further on, you will learn to customize plugins and write cross-platform cookbooks depending on the platform. You will also install packages from a third-party repository and learn how to manage users and applications. Toward the end, you will build high-availability services and explore what Habitat is and how you can implement it.
Table of Contents (9 chapters)
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Preface
Preface
What this book covers
What you need for this book
Who this book is for
Sections
Conventions
Reader feedback
Customer support
Free Chapter
1
1. Chef Infrastructure
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1. Chef Infrastructure
Introduction
Using version control
Installing the Chef Development Kit on your workstation
Using the hosted Chef platform
Managing virtual machines with Vagrant
Creating and using cookbooks
Inspecting files on your Chef server with knife
How to do it…
How it works…
There's more…
See also
Defining cookbook dependencies
Managing cookbook dependencies with Berkshelf
Using custom knife plugins
Deleting a node from the Chef server
Developing recipes with local mode
Using roles
Using environments
Freezing cookbooks
Running the Chef client as a daemon
2
2. Evaluating and Troubleshooting Cookbooks and Chef Runs
2. Evaluating and Troubleshooting Cookbooks and Chef Runs
Introduction
Testing your Chef cookbooks with cookstyle and Rubocop
Flagging problems in your Chef cookbooks with Foodcritic
Test-driven development for cookbooks using ChefSpec
Compliance testing with InSpec
Integration-testing your Chef cookbooks with Test Kitchen
Showing affected nodes before uploading cookbooks
Overriding a node's run list to execute a single recipe
Using chef-shell
Using why-run mode to find out what a recipe might do
Debugging Chef client runs
Inspecting the results of your last Chef run
Using Reporting to keep track of all your Chef client runs
Raising and logging exceptions in recipes
Diff-ing cookbooks with knife
Using community exception and report handlers
3
3. Chef Language and Style
3. Chef Language and Style
Introduction
Using community Chef style
Using attributes to dynamically configure recipes
Using templates
Mixing plain Ruby with Chef DSL
Installing Ruby gems and using them in recipes
Using libraries
Creating your own custom resource
Extending community cookbooks by using application wrapper cookbooks
Creating custom Ohai plugins
Creating custom knife plugins
4
4. Writing Better Cookbooks
4. Writing Better Cookbooks
Introduction
Setting environment variables
Passing arguments to shell commands
Overriding attributes
Using search to find nodes
Using data bags
Using search to find data bag items
Using encrypted data bag items
Accessing data bag values from external scripts
Getting information about the environment
Writing cross-platform cookbooks
Making recipes idempotent by using conditional execution
5
5. Working with Files and Packages
5. Working with Files and Packages
Introduction
Creating configuration files using templates
Using pure Ruby in templates for conditionals and iterations
Installing packages from a third-party repository
Installing software from source
Running a command when a file is updated
Distributing directory trees
Cleaning up old files
Distributing different files based on the target platform
6
6. Users and Applications
6. Users and Applications
Introduction
Creating users from data bags
Securing the Secure Shell daemon
Enabling passwordless sudo
Managing NTP
Installing nginx from source
Creating nginx virtual hosts
Creating MySQL databases and users
Managing Ruby on Rails applications
Managing Varnish
Managing your local workstation with Chef Pantry
7
7. Servers and Cloud Infrastructure
7. Servers and Cloud Infrastructure
Introduction
Creating cookbooks from a running system with Blueprint
Running the same command on many machines at once
Setting up SNMP for external monitoring services
Deploying a Nagios monitoring server
Using HAProxy to load-balance multiple web servers
Using custom bootstrap scripts
Managing firewalls with iptables
Managing fail2ban to ban malicious IP addresses
Managing Amazon EC2 instances
Managing applications with Habitat
8
Index
Index

Using roles

Roles group nodes with similar configurations. Typical cases are using roles for web servers, database servers, and so on.

You can set custom run lists for all the nodes in your roles and override attribute values from within your roles.

Let's see how to create a simple role.

Getting ready

For the following examples, I assume that you have a node named server and that you have at least one cookbook (I'll use the ntp cookbook) registered with your Chef server.

How to do it…

Let's create a role and see what we can do with it:

  1. Create a role:
    mma@laptop:~/chef-repo $ subl roles/web_servers.rb
name "web_servers"
description "This role contains nodes, which act as web servers"
run_list "recipe[ntp]"
default_attributes 'ntp' => {
  'ntpdate' => {
    'disable' => true
  }
}
  2. Upload the role on the Chef server:
    mma@laptop:~/chef-repo $ knife role from file web_servers.rb
Updated Role web_servers
  3. Assign the role to a node called server:
    mma@laptop:~/chef-repo $ knife node run_list add server 'role[web_servers]'
server:
  run_list: role[web_servers]
  4. Log in to your node and run the Chef client:
    user@server:~$ sudo chef-client
...TRUNCATED OUTPUT...
[2016-10-03T18:52:10+00:00] INFO: Run List is [role[web_servers]]
[2016-10-03T18:52:10+00:00] INFO: Run List expands to [ntp]
[2016-10-03T18:52:10+00:00] INFO: Starting Chef Run for server
...TRUNCATED OUTPUT...

How it works...

You define a role in a Ruby (or a JSON) file inside the roles folder of your Chef repository. A role consists of a name attribute and a description attribute. Additionally, a role usually contains a role-specific run list and role-specific attribute settings.

Every node with a role in its run list will have the role's run list expanded into its own. This means that all the recipes (and roles) that are in the role's run list will be executed on your nodes.

You need to upload your role to your Chef server by using the knife role from file command.

Only then should you add the role to your node's run list.

Running the Chef client on a node having your role in its run list will execute all the recipes listed in the role.

The attributes you define in your role will be merged with attributes from environments and cookbooks, according to the precedence rules described at https://docs.chef.io/roles.html#attribute-precedence.

See also

  • Find out how roles can help you find nodes in the Using search to find nodes recipe in Chapter 4, Writing Better Cookbooks
  • Learn more about in the Overriding attributes recipe in Chapter 4, Writing Better Cookbooks
  • Read everything about roles at https://docs.chef.io/roles.html
End of Section 18
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