book

Puppet Best Practices

by Chris Barbour, Jo Rhett

September 2018

Intermediate to advanced

305 pages

7h 30m

English

O'Reilly Media, Inc.

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What Is a Best Practice?Who Should Read This BookWhy We Wrote This BookA Word on Puppet TodayNavigating This BookOnline ResourcesConventions Used in This BookUsing Code ExamplesO’Reilly SafariHow to Contact UsAcknowledgments
Declarative CodeWhat Is Declarative Code, Anyway?Resource Types and ProvidersProcedural ExampleNondeclarative Code with PuppetIdempotencySide EffectsResource-Level IdempotenceRun-Level IdempotenceNondeterministic CodeStatelessBenefits of Stateless DesignSources of State InformationSummary
Code and Data OrganizationCode and Data CategoriesTypes of Code LogicExamples of Logic TypesMapping Data Types to Puppet Use CasesApplication Logic and Puppet ModulesBusiness Logic Should Not Be Written into Component ModulesBusiness Logic with Roles and ProfilesBusiness, Service, Site, Node, and Application DataHiera Data SourcesNode ClassificationSummary
The Style GuideCoding PrinciplesKISS: Keep It SimpleThe Single Responsibility PrincipleSeparation of ConcernsInterface-Driven DesignDRY: Don’t Repeat YourselfDon’t Reinvent the WheelCode PracticesBalance of Resources Versus LogicBalance of Code Versus DataConditional LogicIterationGenerating ListsVariablesVariable NamingReferencing VariablesOther Variable Use CasesTrusted VariablesOrder of Assignment for Top-Level VariablesAssignment with SelectorsAttribute Values Chosen by Conditional EvaluationVariable InheritanceStrict VariablesFunction CallsAlways Use ParenthesesFunctions for Logging and DebuggingString Manipulation FunctionsPath ManipulationInput Validation FunctionsCatalog TestsData TransformationTemplatesERB TemplatesEPP TemplatesEPP Versus ERBOther Language FeaturesSummary
The Puppet Development KitInstalling the Puppet AgentUsing the Ruby that Comes Bundled with PuppetInstalling the Puppet Development KitFavor Editors or IDEs with Puppet PluginsUsing Vendor-Provided or Community ModulesPicking Good ModulesModule ChecklistModule Applicability to Your NeedsContributing ModulesDesigning Modules WellMake Use of Module StructureKeep the Module FocusedDesign Modules for Public ConsumptionPlanning and Scoping Your ModuleBasic Module LayoutThe Module’s Main ClassModule ParametersInput ValidationData in the ModuleThe params.pp PatternHiera Data in ModulesModularizing ClassesDependenciesClass RelationshipsClass ContainmentInterfacing with ClassesReusing Defined TypesProviding Clean Service Interfaces with Defined TypesSimplify Complex Operations with a Defined TypeInteracting with Other Resouces in the ModuleCreating Useful DocumentationREADME, REFERENCE, and Other MarkdownREFERENCE MarkdownSummary
Using Resources to Implement ChangeResource Types Abstract Implementation DetailsUse the Most Specific Resource TypeExamining a Naked ResourceExploring Resources with ToolsResource DeclarationEnsure statesUse Variables for Data-Driven DeclarationUse Arrays for Similar ResourcesUsing Automatic Resource Relationships for Clean CodeResource Declaration by FunctionsResources MetatypesResource MetaparametersAvoid Parse-Order Problems by Using Virtual ResourcesExporting ResourcesOverriding and Modifying Declared ResourcesResource Default StatementsResource ChainingResource CollectorsResource Best PracticesCustom Resource TypesUseful Defined TypesSummary
Separating Code and DataGlobal, Environment, and Module DataHiera BackendsDesigning the Hiera HierarchyVariable InterpolationDesign GuidelinesUseful Hierarchy LevelsEliminating DataAccessing HieraAutomatic Parameter LookupsHiera Function CallsConverting Serialized Hiera Data into Resource DeclarationsInterpolation in Your DataThe Built-In BackendsYAMLJSONHOCONeYAMLCustom Hiera BackendsDatabase and NoSQL EnginesService Discovery BackendsEncrypted Key/Value StorageSummary
RolesCreating Readable RolesDesign Roles for a Singular Use CaseProvide the Role for Use in Data LookupsProfilesA Sample Service ProfileProviding Actionable Data in Profile ParametersImplementing Business Logic in ProfilesDefining Module Relationships in ProfilesCreating Metaprofiles to Group ConfigurationsDesigning an Appropriate Profile StructureTesting Roles and ProfilesValidating Profiles by Using Unit TestsConfirming Profile Implementation with Acceptance TestsSummary
What Data Should the Node Classifier Provide?Roles and ProfilesNode-Specific DataNode StatementsNode Statement MatchingReplacing Node InheritanceNode Parameters Within Node BlocksFact-Based ClassificationFact-Based Role AssignmentSecurity and Fact-Selected Roles or ProfilesFact-Based Hiera ClassificationNode Parameters with Hiera ClassificationAvoiding Node Data in ManifestsServerless ClassificationENCsWhat Data Can an ENC Provide?Puppet Management ConsolesInventory and Infrastructure Management ENCsSummary
Puppet Environments in DepthPuppet Directory EnvironmentsSelectable Blocks for Catalog BuildingEnvironment ConfigurationEnvironment Independence and IsolationDeploying with r10kWhat Does r10k Actually Do?The Control RepositoryControl Repository Branch Contentsr10k Configuration FilePuppetfiler10k Deployment WalkthroughUses for r10kBuild Development EnvironmentsSimplifying Acceptance TestingImplement Continuous Integration, Delivery, and DeploymentDeploy Production EnvironmentsBuild and PackageRelease Management Strategies with r10kStage/Production BranchesSingle Branch (GitHub Flow)GitFlowInvoking r10kPuppet Prerun CommandDeploying on Receipt of a WebHookOrchestrating Deployments with MCollective/ChoriaInvoking r10k in Testing FrameworksCombining Multiple Invocation MethodsMigrating to r10kRepository-per-Module BenefitsConfiguring an Environment in the Control RepositoryEnabling Monolithic and Per-module Hybrid DeploymentMoving Modules to their Own RepositoriesPlacing Roles and Profiles in the site/ Module DirectoryRemove Fully Qualified PathsMoving Shared Tools to Their Own RepositoryImplementing Test CasesBest Practices for Puppet DeploymentsUsing Repository Access Control to Enforce Deployment PolicyEnabling Multiteam CoordinationPinning Module VersionsIsolating Puppet ExtensionsUtilizing Standard Environment Configuration PracticesGit Best PracticesDeployment PracticesSummary

The Cost of Extending PuppetMinimizing Development CostsReducing Upgrade CostsTestingStatic Code AnalysisUnit TestingAcceptance TestingCreating FactsDistributing Facts in ModulesFacts Puppet Can’t KnowStructured FactsAbusing FactsTrusted Certificate AttributesCustom Types and ProvidersAvoiding Creation of Duplicate TypesCreating a New Resource TypeCustom Resource ProvidersReuse Existing FrameworksCreating Custom Hiera BackendsChoose the Appropriate Backend TypeCreating a High-Performance BackendUsing Puppet’s Public Classes and Method CallsPuppet FacesIndirectionDeploying ExtensionspluginsyncDeploying Gem DependenciesDeploying Ruby Gem Extensions on Puppet ServerSummary

Content preview from Puppet Best Practices

Chapter 9. Release Engineering and r10k

r10k is a tool for deploying Puppet modules and environments based on a release specification. In this chapter, we review all the ways in which you can use r10k, with a focus on powerful features that are often overlooked. Because the use of r10k suffers from a lack of useful step-by-step instructions, we have included a walkthrough tutorial.

We then move on to designing release processes using r10k and the best practices for doing so. As such, we cover the following:

How you can use r10k for change control in Puppet
How r10k can simplify and enhance automated unit and acceptance testing
How r10k can enable multiple teams to coordinate effectively
How r10k can provide compliance auditing and controls without hampering development

Puppet Enterprise includes Code Manager, which has identical functionality and a shared parentage with r10k. Everything in this chapter also applies to Code Manager except for the r10k.yaml configuration file.

Further, there are several other tools that mimic r10k functionality and implement improvements for a specific need. All of the advice in this chapter applies to those tools, as well.

Although r10k is currently the best-practice tool to implement the workflows described here, it is not the only solution. This chapter covers testing, release, deployment, and CI strategies in general for Puppet. These topics are applicable to Puppet regardless of the deployment tool that you use.