book

Customizing Chef

Name: Customizing Chef
Author: Jon Cowie
ISBN: 9781491949375

by Jon Cowie

August 2014

Intermediate to advanced

388 pages

9h 49m

English

O'Reilly Media, Inc.

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Dedication
Foreword
Preface
Who This Book Is ForHow This Book Is OrganizedConventions Used in This BookUsing Code ExamplesSafari® Books OnlineHow to Contact UsAcknowledgments
I. Chef and Ruby 101
1. Introduction
What Is Configuration Management?So Why Chef?Think CriticallyMeet AwesomeIncCriteria for CustomizationHow Do We Find Out When Our Chef Runs Are Failing, and Why?How Do We Simplify Our Recipes to Reduce the Amount of Replicated Code?How Do We Stop Our Developers and Ops Staff from Treading All over Each Other’s Changes?State of the Customization NationChef SupermarketDevelopment ToolingWorkflow ToolingKnife PluginsHandlersRecipes and ResourcesChef Installation Types and Limitationschef-soloOpen Source ChefLocal ModePrivate Enterprise ChefHosted Enterprise ChefPrerequisitesKnifeNodes and ClientsCookbooks, Attributes, Roles, Environments, and Data BagsChef SearchRubyAssumptions
2. Just Enough Ruby to Customize Chef
Ruby Is Object-OrientedRuby Is Dynamically TypedClassesGetter and Setter MethodsVariable ScopingLocal VariablesClass Instance VariablesInheritanceModulesModules as NamespacesModules as MixinsUsing Other Classes and ModulesLocal ClassesRubyGemsBuilt-in ClassesWhen Things Go WrongExceptionsHandling ExceptionsDefining Custom Exception TypesTying It All TogetherFile OperationsHTTP RequestsSummary
3. Chef Internals
Chef ArchitectureChef Client ToolsChef ServerAnatomy of a Chef RunGet Configuration DataOhaiAuthenticate/RegisterLoad and Build Node ObjectSynchronize CookbooksSetUp RunContextLoad Cookbook DataConverge NodeFinalizeDry-Run and Why-RunThe Problem with Dry-RunWhy-Run ModeUsefulness of Why-RunUsing the SourceGetting the Chef Source CodeChef Source StructureTracing a chef-client RunExecute the chef-client CommandRun the Real chef-client ScriptThe Chef::Application::Client ClassThe Chef::Application::Client run_chef_client MethodThe Chef::Client ClassThe Chef::Client Class do_run MethodSummary
II. Customizing Chef Runs
4. Extending Ohai
IntroductionOhai Attribute CollectionThe Ohai Source CodeOhai Example 1: Plugin SkeletonTesting and Running Ohai PluginsTesting Using irbRunning Using ChefOhai Example 2: Adding More to the PluginThe Mash ObjectMultiple collect_data MethodsRunning example2.rbOhai Example 3: Multilevel PluginsSummary
5. Creating Handlers
Preparing a Test EnvironmentCreate the Test chef-client ConfigurationCreate a Test CookbookVerify That the Test Environment Works CorrectlyIntroduction to HandlersThe Run Status ObjectRun Status MethodsRun Information MethodsRun Object MethodsHandler Example 1: Start HandlerHandler Example 2: Report HandlerHandler Example 3: Exception HandlerHandlers: Summary and Further Reading

6. Extending Chef Run Events
Introduction to the Event DispatcherEvent Dispatcher InitializationPublish OverviewSubscribe OverviewCreating FormattersFormatter Example 1: Skeleton FormatterFormatter Example 2: Slightly Less SkeletalFormatter Example 3: Custom Event MethodsSetting the Default FormatterFormatters: Summary and Further ReadingCreating Custom SubscribersSubscriber Example 1: Skeleton SubscriberSubscriber Example 2: Registration with Start HandlersSubscriber Example 3: Custom Event MethodsCustom Subscribers: SummaryRevisiting AwesomeInc—Which Customization?Summary
III. Customizing Recipes
7. Definitions and Libraries
Cookbook Structure RevisitedCreating a Test EnvironmentDefinitionsWhat Is a Definition?Definition Example 1: SkeletonAdding ParametersDefinition Example 2: Using ParametersAdding ResourcesDefinition Example 3: Using ResourcesLibrariesWhat Is a Library?Library Example 1: Modules and MixinsLibrary Example 2: Methods in a Custom NamespaceLibrary Example 3: Extending Core Chef ClassesSummary and Further Reading
8. Lightweight Resources and Providers
Introduction to Resources and ProvidersAutomatically Choosing ProvidersResources and Providers—Lightweight Versus HeavyweightIntroduction to LWRPsLWRP Example 1: Getting Started with LWRPsExample 1: Creating a ResourceExample 1: Creating a ProviderExample 1: Using Our LWRP in a RecipeThe LWRP Domain-Specific LanguageResource DSLProvider DSLLWRP Example 2: Extending the ProviderProvider InternalsDesired Resource StateCurrent Resource StateIdentifying and Executing ChangesKeep it simple, keep it relevantPick your state object sensiblyRemember the criteriaInforming Chef About UpdatesLWRP Example 3: Native ProviderExample 3: Preparing the Resource and ProviderExample 3: The load_current_resource MethodExample 3: Coding the ActionsSummary and Further Reading
9. Heavyweight Resources and Providers
Introduction to HWRPsWhy Write HWRPs?HWRPs in CookbooksHWRP Example 1: Getting Started with HWRPsExample 1: Creating a ResourceExample 1: Creating a ProviderExample 1: Using Our HWRP in a RecipeExample 1: Extending the ProviderAdvanced HWRP TricksMixing HWRPs and LWRPsOverriding Automatic Provider ResolutionImplementing Multi-Provider ResourcesHWRP Example 2: Extending the package ResourceExample 2: Creating a ProviderExample 2: Using Our Provider in a RecipeExample 2: Tapping into Chef’s Provider MappingSummary and Further Reading
IV. Other Customizations
10. Customizing Knife
The Knife Source CodeIntroduction to Knife PluginsAnatomy of a Knife CommandStep 1: Validate and Parse OptionsStep 2: Load PluginsStep 3: Get Subcommand ClassStep 4: Load DependenciesStep 5: Create Subcommand ObjectStep 6: Run PluginCreating a Test EnvironmentPrerequisites and PreparationVerifying That the Test Environment Works CorrectlyKnife Example 1: Wrapping an Existing PluginPresenting Presenters!Chef::Knife::Core::GenericPresenterChef::Knife::Core::NodePresenterThe UI ClassUser Interaction MethodsMessage Output MethodsOther Output MethodsObject Editing MethodsHighLine MethodsKnife Example 2: Search PluginWorking with Chef ObjectsLoading Objects: SearchingLoading Objects: Direct LoadingEditing and Saving Objects NoninteractivelyEditing and Saving Objects InteractivelyCreating and Updating Objects from FilesKnife Example 3: Tying It All TogetherRevisiting AwesomeInc—Plugin Best PracticesSummary and Further Reading
11. The Chef API
Introduction to the Chef APISo Why Use the Chef API?Authenticating to the Chef APICreating a Test EnvironmentAPI Example 1: Authenticating and Making a GET RequestThe Chef::Rest ClassAPI Example 2: Combining Multiple API RequestsError HandlingSecrets of the Chef APIThe /_status EndpointPartial SearchSummary and Further Reading
12. Contributing Your Customizations
DocumentationSupporting Your CodeManaging ContributionsTesting Your SoftwareRuby and Infrastructure Testing ToolsContinuous Integration ToolsChef-Specific ToolingFurther ReadingVersioning Your SoftwareSemantic VersioningLicensing and CopyrightCopyrightLicensing Your CodeDistributing Your CustomizationsSharing the Source CodeCommunity CookbooksRubyGemsDistribution via CookbookSummary
A. Chef API Endpoints and Verbs
Index
Colophon
Copyright

Overview

Take advantage of Chef’s highly customizable design to tackle specific automation issues that you can’t solve by simply using Chef’s tools, resources, and services out of the box. With this practical guide, you’ll examine the internal structure of this configuration management technology and learn where, how, and why to add custom code.

Author Jon Cowie not only provides code snippets and practical advice for customizing Chef, but also helps you determine case by case whether it’s in your best interests to customize at all. If you have intermediate-to-advanced Chef experience, this book is indispensable.

Explore Chef’s typical setups and why you’d want to customize them
Learn the Ruby concepts needed to write customizations
Customize the Chef run process and explore Chef’s internal classes
Gain more insight into your Chef runs through handlers and Chef’s event stream
Level up your Chef recipes by writing your own resources and providers
Create and extend plugins for Knife—Chef’s command-line tool
Interact with the Chef API to write scripts and reports
Learn how to contribute customizations to the Chef community

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