Mastering Chef

Table of Contents

Mastering Chef

Credits

About the Author

About the Reviewers

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Free access for Packt account holders

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Downloading the example code

Errata

Piracy

Questions

1. Introduction to the Chef Ecosystem

Different modes of running Chef

Terminology used in the world of Chef

The anatomy of a Chef run

A Chef run using chef-client

Step 1 – Building a node object

Step 2 – Authenticate

Step 3 – Synchronization of cookbooks

Step 4 – Loading of cookbooks and convergence

Step 5 – Reporting and exception handling

Using chef-solo

Setting up a work environment

Summary

2. Knife and Its Associated Plugins

Introducing Knife

Managing cookbooks

Creating a new cookbook

Uploading a cookbook to chef-server

Getting the list of all the cookbooks on chef-server

Deleting cookbooks

Downloading a cookbook

Deleting multiple cookbooks

Managing environments

Creating an environment

Deleting an environment

Editing an environment

Listing all environments

Displaying information about an environment

Managing roles

Creating a new role

Deleting a role

Editing a role

Listing all available roles

Displaying information about a role

Managing nodes

Creating a node

Listing all available nodes

Displaying information about a node

Editing a node

Adding stuff to the run_list associated with a node

Deleting stuff from the run_list associated with a node

Deleting a node object

Managing an API client

Creating a new client

Listing all available API clients

Displaying information about a client

Deleting an existing client

Reregistering a client

The search command

Bootstrapping a node

Some useful Knife plugins

The knife-ssh plugin

The knife-ec2 plugin

The knife-azure plugin

The knife-google plugin

The knife-push plugin

Summary

3. Chef and Ruby

Ruby

IRB

Variables and types

Symbols

Basic operations

Arithmetic operators

Comparison operators

Assignment operators

Bitwise operators

Logical operators

The Ruby ternary operator

Ruby range operators

The Ruby defined? operator

Conditional statements and loops

The if statement

The unless statement

The case/when statement

The while loop

The until loop

The for loop

Methods

Blocks

Arrays

Creating an array

Accessing elements of an array

Adding elements to an array

Removing elements from an array

Iterating over an array

Selecting elements of an array

The nondestructive way

The destructive way

Bang methods

Hashes

Creating hashes

Iterating over a hash

Classes and objects

What's an object and a class?

Modules

Summary

4. Controlling Access to Resources

The bootstrap process

Authentication

chef-client

Knife

Custom API calls

Authorization

The Open Source Chef server

Enterprise Chef

Object permissions

Groups

Summary

5. Starting the Journey to the World of Recipes

Resources

Guard attributes

Lazy evaluation of attributes

The package resource

The cookbook_file resource

The directory resource

The file resource

The execute resource

The cron resource

The service resource

The bash resource

The template resource

Helper modules

Inline methods

Inline modules

Library modules

Partial templates

Recipes

Attributes

Types of attributes

Including recipes

The run_list

Recipe DSL methods

The platform method

The platform_family method

The value_for_platform method

The value_for_platform_family method

The attribute method

The resources method

Best practices when writing recipes

Summary

6. Cookbooks and LWRPs

Cookbooks

Authoring a cookbook

Uploading a cookbook to the Chef server

Deleting a cookbook

Testing a cookbook

Cookbook versioning

Operators available for use with versioning

Freezing versions

Maintaining multiple versions of cookbooks

Maximum version control strategy

Branch tracking strategy

Custom resources

Setup

Resource

Provider

Provider DSL

Logging

Summary

7. Roles and Environments

Managing roles

Using Knife

Creating a new role

Editing an existing role

Deleting an existing role

Showing details about an existing role

Listing all roles on the Chef server

Using Ruby DSL

Using a JSON file

Using the Chef API

Using the Chef server WebUI

Managing environments

Using Knife

Creating a new environment

Editing an environment configuration

Deleting an environment

Displaying all the environments configured on the Chef server

Showing details associated with an environment

Comparing cookbook versions across environments

Creating or editing an environment using the configuration specified in a file

Using Ruby DSL

Setting up an environment on a node

Using Knife

Editing the client.rb file on the node

Role and environment attributes

Attribute precedence

Environment run lists

Summary

8. Attributes and Their Uses

Attribute naming

Different types of attributes

Different sources of attributes

The attribute file

Recipes

Roles and environments

Ohai

Attribute precedence

Attribute whitelisting

Summary

9. Ohai and Its Plugin Ecosystem

Running the Ohai binary

Ohai plugins

Custom plugins

Logging in Ohai plugins

Summary

10. Data Bags and Templates

Data bags

Management of a data bag

Creating a data bag

Editing a data bag item

Deleting a data bag item or a data bag

Getting a list of all the data bags set up on the Chef server

Getting a list of items and their properties

Using the data bags in recipes

Encrypted data bags

Templates

Template resources and a template in action

Partial templates

Summary

11. Chef API and Search

Prerequisites for using Chef API

Authentication of requests

Endpoints

/users

GET

POST

/users/NAME

DELETE

GET

POST

PUT

/clients

GET

POST

/clients/NAME

DELETE

GET

PUT

/roles

GET

POST

/roles/NAME

DELETE

GET

PUT

/roles/NAME/environments

GET

/roles/NAME/environments/NAME

GET

/cookbooks

GET

/cookbooks/NAME

GET

/cookbooks/NAME/VERSION

DELETE

GET

PUT

/data

GET

POST

/data/NAME

DELETE

GET

POST

/data/NAME/ITEM

DELETE

GET

PUT

/environments

GET

POST

/environments/NAME

DELETE

GET

PUT

/environments/NAME/cookbooks

GET

/environments/NAME/nodes

GET

/environments/NAME/recipes

GET

/environments/NAME/roles/NAME

Search

/search

GET

/search/INDEX

GET

POST

Patterns

Syntax

Exact matching

Wildcard matching

Range matching

Fuzzy matching

Operators

Using search in recipes

Ridley

Summary

12. Extending Chef

Custom Knife plugins

The skeleton of a Knife plugin

Namespace

Class name

Banner

Dependencies

Requirements

Options

Arguments

The run method

Search inside a custom Knife plugin

knife.rb settings

User interactions

Exception handling

A simple Knife plugin

Distributing plugins using gems

Custom Chef handlers

Summary

13. (Ab)Using Chef

The dynamic server list in Capistrano using Chef

Installing Capistrano

Capistrano style deployments using Chef's deploy resource

Phases of deployment

Callbacks

Actions

Attributes

Extending Chef to bootstrap distributed systems

Running jobs from your workstation

Running jobs from within recipes

Test-driven development with Chef

Development without TDD

Development with TDD

Types of tests

What to use where

How do we simulate a real-world scenario?

Tools

Using Chef in a dynamic environment such as the cloud

Summary

Index

Mastering Chef

Mastering Chef

Copyright © 2015 Packt Publishing

All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.

Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author, nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book.

Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.

First published: June 2015

Production reference: 1240615

Published by Packt Publishing Ltd.

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ISBN 978-1-78398-156-4

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Credits

Author

Mayank Joshi

Reviewers

Omri Bahumi

Evgeny Goldin

Panagiotis Papadomitsos

Commissioning Editor

Edward Gordon

Acquisition Editor

Meeta Rajani

Content Development Editor

Parita Khedekar

Technical Editors

Manali Gonsalves

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Copy Editors

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Project Coordinator

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Proofreader

Safis Editing

Indexer

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Graphics

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Production Coordinator

Komal Ramchandani

Cover Work

Komal Ramchandani

About the Author

Mayank Joshi works for Indix as a DevOps engineer. He has worn many hats during his 10-year long career. He has been a developer, a systems analyst, a systems administrator, a software consultant, and for the past 6 years, he has been fascinated with the phenomenal growth witnessed in cloud environments and the challenges of automation associated with the hosting of the infrastructure in such environments. Prior to Indix, he worked for start-ups such as SlideShare, R&D organizations such as CDAC, and even had a stint at a highly automated chemical plant of IFFCO.

I would like to thank all my fellow colleagues at Indix for their wonderful support and allowing me to get some spare time amid some very tight work schedules.

I wouldn't have been able to work on cloud platforms and configuration management systems had I not associated with SlideShare. Thanks much, guys!

I would also like to thank my family for bearing with me while I was spending most of the time either working or writing the book.

Last but not least, special thanks to the wonderful team at Packt, especially Parita and Meeta, who really pushed me whenever I was losing focus.

About the Reviewers

Omri Bahumi started his relationship with Linux in 1999 at the age of 12. Since then, he has managed to engage with various areas of Linux-based production systems—from high performance network servers to low-level debugging and advanced networking trickery. He serves in EverythingMe's operations team, where he's in charge of designing, building, and deploying multi-data center cloud infrastructures for developers and users alike. A typical day in his life includes a mixture of having coffee, coding in various languages, managing AWS stacks, taming Docker and Chef, and working with engineers on upcoming features (not necessarily in this order). In his spare time, he likes to hack on Arduino, Raspberry Pi, ESP8266, and all sorts of programmable hardware, making cool electronic projects.

Evgeny Goldin is a Ruby, Groovy, and Scala software developer who turned into an automation and release engineer to introduce order where chaos usually reigns. On an average day, all things related to cloud, automation, and continuous delivery get his immediate attention. Back at home, he's a proud father of a 1-year-old son, dreaming of a day when a proper tech talk would happen between the two! When he has any spare time left, he explores the subjects of aviation safety, functional programming, and web security. He's an open source developer, speaker, and passionate advocate when it comes to tools and techniques that lead to smooth and painless release processes.

Panagiotis Papadomitsos is a distributed systems architect in the mobile intelligence division of Splunk, where he is responsible for the design, implementation, and maintenance of a self-healing, always-on highly distributed application mesh that spans three clouds and receives more than 450 billion events per hour from devices spread across the globe. He's been working with distributed systems for the past 10 years in various companies and positions, with responsibilities ranging from designing and implementing complex heterogeneous infrastructures using Chef and the Chef ecosystem to architecting and coding low-latency distributed applications in Erlang and Nginx/Lua, contributing code back to the community whenever possible. He is a performance-tuning enthusiast; you'll often find him measuring and optimizing critical code execution paths from the application level down to the OS kernel level. When away from the computer screen, he enjoys surfing, snowboarding, and playing the guitar.

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Preface

The core philosophy behind configuration management systems has its roots in the US Department of Defense, where it was adopted as a technical management discipline. Today, the philosophy has been adopted by many other disciplines, including systems and software engineering. The basic idea behind a configuration management system is to establish and maintain the consistency of a system or product throughout its lifetime. The following are the fundamental activities associated with any configuration management system:

The purpose of configuration management systems is to ensure that the state of the system isn't residing in the minds of people, but inside a revision control system, from which it's easy to figure out the current state of the system along with the changes that have been made to the underlying system over the course of time. It not only allows to record what changes were made, but also why the changes were made.

With a phenomenal increase in the usage of cloud platforms, new challenges have emerged for system architects, as they now need to design systems that are able to scale up the size of the infrastructure upon the demands laid down by the application's needs, and the manual configuration of systems in such a dynamic environment is just not possible.

Chef is a configuration management system developed by Opscode and is one of the most widely used systems in its category. It allows you to define the infrastructure as a code, and it can be used to build, deploy, and automate your infrastructure. With Chef, the infrastructure becomes as versionable, testable, and repeatable as an application code.

Mastering Chef is an attempt to provide in-depth knowledge of the underlying system. It provides users with insights into different components of the underlying system and also provides users with insight into the APIs that can be used to either extend Chef, or build toolsets around the ecosystem.

What this book covers

Chapter 1, Introduction to the Chef Ecosystem, serves as a reference to new users of Chef. After a brief introduction, we jump into the anatomy of a chef-client run and at the end, we'll see how to go about setting up our workstation for the development of a Chef code that is thoroughly tested before being pushed to the production environment.

Chapter 2, Knife and Its Associated Plugins, introduces the reader to one of the most widely used tools in the Chef ecosystem, called Knife. We will learn to use Knife to bootstrap instances and also learn about different plugins that can be used to accomplish daily routine tasks in a more efficient way.

Chapter 3, Chef and Ruby, brings a user up to speed with the required Ruby knowledge, thereby allowing them to write a more efficient infrastructure code. By the end of this chapter, the user will be equipped with enough knowledge of Ruby to extend the code for infrastructure provisioning, beyond what can be accomplished by merely using the DSL provided by Chef.

Chapter 4, Controlling Access to Resources, introduces the concept of organization, groups, and users, and explains how you can allow fine-grained access to different types of objects residing on the Chef server.

Chapter 5, Starting the Journey to the World of Recipes, introduces the reader to the most fundamental unit of code written by Chef developers—recipes. We'll learn about the different components of a recipe and get an understanding of the different resources that can be used to manage our infrastructure.

Chapter 6, Cookbooks and LWRPs, introduces users to cookbooks and how you can extend chef-client through the use of lightweight resource/provider. Readers will also learn how to create their own custom LWRPs by the end of this chapter.

Chapter 7, Roles and Environments, explains that, most of the time, a server is not just associated with one particular task and can perform many different operations. For example, you might have a web server that is also performing the role of an application server and a proxy. Roles allow users to attach multiple recipes to a server. Also, in most organizations, infrastructure is classified into different environments depending upon the use. For example, an organization might have a dev, QA, staging, and production environment. The configuration of applications running across these environments will be different to some extent. This chapter will explain what a role is, how we can group multiple recipes in a role, and how to use roles inside a recipe to do things conditionally. We'll also learn how you can manage different environments in your infrastructure using Chef.

Chapter 8, Attributes and Their Uses, explains that every service and a server can be identified with a role and set of properties associated with it. Some properties are system specific, such as the IP address, kernel, hostname, and so on. While they are necessary, an effective infrastructure code always needs more properties that can define the services and the server itself in a more precise manner. In this chapter, we'll see what the different types of attributes are and how to override values of the attributes.

Chapter 9, Ohai and Its Plugin Ecosystem, explains that as part of a chef-client run, many details related to the underlying system, such as architecture, operating system, network details, filesystem, and so on, are required to be collected by Chef. Ohai is a tool that allows for this. In this chapter, we'll learn about Ohai and its plugin-based architecture and associated plugins. We'll also learn how to write our own custom Ohai plugins.

Chapter 10, Data Bags and Templates, explains that in highly dynamic environments such as cloud, a configuration management system is only as good as its support for allowing the specification of the configuration in a form that is dynamic. Templates are just what the doctor ordered for this use case. Data bags, on the other hand, are data stores containing the data stored in a JSON format. In this chapter, we'll learn how to make effective use of databags and templates to define our infrastructure.

Chapter 11, Chef API and Search, explains that the Chef API is perhaps one of the most powerful features of Chef. Chef has a really wonderful API and its search facility is what makes it really fun to use. There are lots of cases where you can make use of Chef's API to build tools that can help in the efficient automation of the tasks. In this chapter, we'll look at Chef's API, using search in a recipe using Chef API, and also using a search through Knife.

Chapter 12, Extending Chef, covers the writing of a custom code suited for our requirements that will help us to extend the functionality of Chef. We'll learn how to write custom Knife plugins and custom Chef handlers.

Chapter 13, (Ab)Using Chef, explores some fun uses of Chef, which will allow an increase in productivity, while managing a large scale infrastructure. We'll see how we can extend tools such as Capistrano by using Chef API. We'll also learn how to manage large distributed clusters using an extension of Chef called Ironfan. We will also look at tools such as the Push Job server, which can be used for the orchestration of chef-client runs across a set of instances.

What you need for this book

All the code in this book is written/tested against Chef 12.x. A basic list of software required to run the code in this book is as follows:

Operating system: Mac OS X/Linux/Windows

Ruby: 1.9.3+

Chef: 12.x

Git

Editor: Atom/Sublime/Vi/Emacs/TextMate

Who this book is for

This is a book for anyone who is interested in learning about Chef. You are not required to have any prior experience with the use of Chef or any configuration management system. You aren't expected to have experience with programming in Ruby; however, some experience with the fundamentals of programming will definitely be helpful.

Conventions

In this book, you will find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: Let's see what the knife command has to offer to us.

A block of code is set as follows:

knife[:aws_access_key_id] = AWS_ACCESS_KEY

knife[:aws_secret_access_key] = AWS_SECRET_KEY

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

node_name                'mayank' client_key            '~/keys/chef/mayank.pem'

validation_client_name  'chef-validator'

Any command-line input or output is written as follows:

$ knife search '*:*'

New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: Once you are done with it, click on the Create Role button.

Note

Warnings or important notes appear in a box like this.

Tip

Tips and tricks appear like this.

Reader feedback

Feedback from our readers is always welcome. Let us know what you think about this book—what you liked or may have disliked. Reader feedback is important for us to develop titles that you really get the most out of.

To send us general feedback, simply send an e-mail to <[email protected]>, and mention the book title via the subject of your message.

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Errata

Although we have taken every care to ensure the accuracy of our content, mistakes do happen. If you find a mistake in one of our books—maybe a mistake in the text or the code—we would be grateful if you would report this to us. By doing so, you can save other readers from frustration and help us improve subsequent versions of this book. If you find any errata, please report them by visiting http://www.packtpub.com/submit-errata, selecting your book, clicking on the errata submission form link, and entering the details of your errata. Once your errata are verified, your submission will be accepted and the errata will be uploaded on our website, or added to any list of existing errata, under the Errata section of that title. Any existing errata can be viewed by selecting your title from http://www.packtpub.com/support.

Piracy

Piracy of copyright material on the Internet is an ongoing problem across all media. At Packt, we take the protection of our copyright and licenses very seriously. If you come across any illegal copies of our works, in any form, on the Internet, please provide us with the location address or website name immediately so that we can pursue a remedy.

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We appreciate your help in protecting our authors, and our ability to bring you valuable content.

Questions

You can contact us at <[email protected]> if you are having a problem with any aspect of the book, and we will do our best to address it.

Chapter 1. Introduction to the Chef Ecosystem

Chef is a configuration management system written partly in Ruby and Erlang.

Before we begin our exciting journey towards becoming Chef masters, I think it would be prudent on our part to understand the underlying ecosystem.

The Chef ecosystem is primarily comprised of the following components:

WebUI: This is a Rails application that is used to view information about the Chef server over the Web.

ErChef: Prior to version 11.x, the Chef server API core (the code responsible for catering to requests by Knife or chef-client) was written in Ruby. However, since 11.x, this code has been rewritten in Erlang.

Bookshelf: This is used to store cookbooks content such as files, templates, and so on, that have been uploaded to chef-server as part of a cookbook version.

chef-solr: This is a wrapper around Apache Solr and is used to handle the REST API for indexing and search.

Rabbit MQ: This is used as a message queue for the Chef server. All items that are to be added to a search index repository are first added to a queue.

chef-expander: This is a piece of code that pulls messages from the RabbitMQ queue, processes them into a desired format, and finally posts them to Solr for indexing.

PostgreSQL: This is another major change since version 11.x. Earlier, CouchDB used to be the data storage; however, since version 11.x, PostgreSQL has become the data storage solution used by Chef.

chef-client: This is a Ruby application that runs on every machine that needs to be provisioned. It handles the task of authenticating with chef-server, registering nodes, synchronizing cookbooks, compiling resource collections, handling exceptions and notifications, and so on.

Knife: This is a Ruby application that provides an interface between a local chef repository and the Chef server.

The typical architecture of the Chef ecosystem can be understood by looking at the following figure:

Other than these components, we've chef-shell (shef), Ohai, and chef-solo that form an integral part of