book

Ansible: Up and Running

Name: Ansible: Up and Running
Author: Lorin Hochstein
ISBN: 9781491915325

by Lorin Hochstein

May 2015

Intermediate to advanced

200 pages

7h 14m

English

O'Reilly Media, Inc.

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Foreword
Preface
Why I Wrote This BookWho Should Read This BookNavigating This BookConventions Used in This BookOnline ResourcesSafari® Books OnlineHow to Contact UsAcknowledgments
1. Introduction
A Note About VersionsAnsible: What Is It Good For?How Ansible WorksWhat’s So Great About Ansible?Easy-to-Read SyntaxNothing to Install on the Remote HostsPush-BasedAnsible Scales DownBuilt-in ModulesVery Thin Layer of AbstractionIs Ansible Too Simple?What Do I Need to Know?What Isn’t CoveredInstalling AnsibleSetting Up a Server for TestingUsing Vagrant to Set Up a Test ServerTelling Ansible About Your Test ServerSimplifying with the ansible.cfg FileMoving Forward
2. Playbooks: A Beginning
Some PreliminariesA Very Simple PlaybookSpecifying an nginx Config FileCreating a Custom HomepageCreating a Webservers GroupRunning the PlaybookPlaybooks Are YAMLStart of FileCommentsStringsBooleansListsDictionariesLine FoldingAnatomy of a PlaybookPlaysTasksModulesPutting It All TogetherDid Anything Change? Tracking Host StateGetting Fancier: TLS SupportGenerating TLS certificateVariablesGenerating the Nginx Configuration TemplateHandlersRunning the Playbook
3. Inventory: Describing Your Servers
The Inventory FilePreliminaries: Multiple Vagrant MachinesBehavioral Inventory Parametersansible_connectionansible_shell_typeansible_python_interpreteransible_*_interpreterChanging Behavioral Parameter DefaultsGroups and Groups and GroupsExample: Deploying a Django AppAliases and PortsGroups of GroupsNumbered Hosts (Pets versus Cattle)Hosts and Group Variables: Inside the InventoryHost and Group Variables: In Their Own FilesDynamic InventoryThe Interface for a Dynamic Inventory ScriptWriting a Dynamic Inventory ScriptPre-Existing Inventory ScriptsBreaking Out the Inventory into Multiple FilesAdding Entries at Runtime with add_host and group_byadd_hostgroup_by
4. Variables and Facts
Defining Variables in PlaybooksViewing the Values of VariablesRegistering VariablesFactsViewing All Facts Associated with a ServerViewing a Subset of FactsAny Module Can Return FactsLocal FactsUsing set_fact to Define a New VariableBuilt-in Variableshostvarsinventory_hostnameGroupsSetting Variables on the Command LinePrecedence
5. Introducing Mezzanine: Our Test Application
Why Deploying to Production Is ComplicatedPostgreSQL: The DatabaseGunicorn: The Application ServerNginx: The Web ServerSupervisor: The Process Manager
6. Deploying Mezzanine with Ansible
Listing Tasks in a PlaybookOrganization of Deployed FilesVariables and Secret VariablesUsing Iteration (with_items) to Install Multiple PackagesAdding the Sudo Clause to a TaskUpdating the Apt CacheChecking Out the Project Using GitInstalling Mezzanine and Other Packages into a virtualenvComplex Arguments in Tasks: A Brief DigressionCreating the Database and Database UserGenerating the local_settings.py File from a TemplateRunning django-manage CommandsRunning Custom Python Scripts in the Context of the ApplicationSetting Service Configuration FilesEnabling the Nginx ConfigurationInstalling TLS CertificatesInstalling Twitter Cron JobThe Full PlaybookRunning the Playbook Against a Vagrant MachineDeploying Mezzanine on Multiple Machines
7. Complex Playbooks
Running a Task on the Control MachineRunning a Task on a Machine Other Than the HostManually Gathering FactsRunning on One Host at a TimeRunning Only OnceDealing with Badly Behaved Commands: changed_when and failed_whenRetrieving the IP Address from the HostEncrypting Sensitive Data with VaultPatterns for Specifying HostsLimiting Which Hosts RunFiltersThe Default FilterFilters for Registered VariablesFilters That Apply to File PathsWriting Your Own FilterLookupsfilepipeenvpasswordtemplatecsvfilednstxtredis_kvetcdWriting Your Own Lookup Plug-inMore Complicated Loopswith_lineswith_fileglobwith_dictLooping Constructs as Lookup Plug-ins
8. Roles: Scaling Up Your Playbooks
Basic Structure of a RoleExample: Database and Mezzanine RolesUsing Roles in Your PlaybooksPre-Tasks and Post-TasksA “Database” Role for Deploying the DatabaseA “Mezzanine” Role for Deploying MezzanineCreating Role Files and Directories with ansible-galaxyDependent RolesAnsible GalaxyWeb InterfaceCommand-Line InterfaceContributing Your Own Role

9. Making Ansible Go Even Faster
SSH Multiplexing and ControlPersistManually Enabling SSH MultiplexingSSH Multiplexing Options in AnsiblePipeliningEnabling PipeliningConfiguring Hosts for PipeliningFact CachingJSON File Fact-Caching BackendRedis Fact Caching BackendMemcached Fact Caching BackendParallelismAccelerated ModeFireball Mode
10. Custom Modules
Example: Checking That We Can Reach a Remote ServerUsing the Script Module Instead of Writing Your Owncan_reach as a ModuleWhere to Put Custom ModulesHow Ansible Invokes ModulesGenerate a Standalone Python Script with the Arguments (Python Only)Copy the Module to the HostCreate an Arguments File on the Host (Non-Python Only)Invoke the ModuleExpected OutputsOutput Variables Ansible ExpectsImplementing Modules in PythonParsing ArgumentsAccessing ParametersImporting the AnsibleModule Helper ClassArgument OptionsAnsibleModule Initializer ParametersReturning Success or FailureInvoking External CommandsCheck Mode (Dry Run)Documenting Your ModuleDebugging Your ModuleImplementing the Module in BashSpecifying an Alternaive Location for BashExample Modules
11. Vagrant
Convenient Vagrant Configuration OptionsPort Forwarding and Private IP AddressesEnabling Agent ForwardingThe Ansible ProvisionerWhen the Provisioner RunsInventory Generated by VagrantProvisioning in ParallelSpecifying Groups
12. Amazon EC2
TerminologyInstanceAmazon Machine ImageTagsSpecifying CredentialsEnvironment VariablesConfiguration FilesPrerequisite: Boto Python LibraryDynamic InventoryInventory CachingOther Configuration OptionsAuto-Generated GroupsDefining Dynamic Groups with TagsApplying Tags to Existing ResourcesNicer Group NamesEC2 Virtual Private Cloud (VPC) and EC2 ClassicConfiguring ansible.cfg for Use with ec2Launching New InstancesEC2 Key PairsCreating a New KeyUpload an Existing KeySecurity GroupsPermitted IP AddressesSecurity Group PortsGetting the Latest AMIAdding a New Instance to a GroupWaiting for the Server to Come UpCreating Instances the Idempotent WayPutting It All TogetherSpecifying a Virtual Private CloudDynamic Inventory and VPCBuilding AMIsWith the ec2_ami ModuleWith PackerOther Modules
13. Docker
The Case for Pairing Docker with AnsibleDocker Application Life CycleDockerizing Our Mezzanine ApplicationCreating Docker Images with AnsibleMezzanineThe Other Container ImagesPostgresMemcachedNginxCertsBuilding the ImagesDeploying the Dockerized ApplicationStarting the Database ContainerRetrieving the Database Container IP Address and Mapped PortWaiting for the Database to Start UpInitializing the DatabaseStarting the Memcached ContainerStarting the Mezzanine ContainerStarting the Certificate ContainerStarting the Nginx ContainerThe Entire Playbook
14. Debugging Ansible Playbooks
Debugging SSH IssuesThe Debug ModuleThe Assert ModuleChecking Your Playbook Before ExecutionSyntax CheckList HostsList TasksCheck ModeDiff (Show File Changes)Limiting Which Tasks RunStepStart-at-TaskTagsOnward
A. SSH
Native SSHSSH AgentStarting Up ssh-agentMac OS XLinuxAgent ForwardingSudo and Agent ForwardingHost Keys
B. Default Settings
C. Using IAM Roles for EC2 Credentials
AWS Management ConsoleCommand-Line
Glossary
Bibliography
Index

Content preview from Ansible: Up and Running

Chapter 11. Vagrant

Vagrant is a great environment for testing Ansible playbooks, which is why I’ve been using it all along in this book, and why I often use Vagrant for testing my own Ansible playbooks.

Vagrant isn’t just for testing configuration management scripts; it was originally designed to create repeatable development environments. If you’ve ever joined a new software team and spent a couple of days discovering what software you had to install on your laptop so you could run a development version of an internal product, you’ve felt the pain that Vagrant was built to alleviate. Ansible playbooks are a great way to specify how to configure a Vagrant machine so newcomers on your team can get up and running on day one.

Vagrant has some built-in support for Ansible that we haven’t been taking advantage of. In this chapter, we’ll cover Vagrant’s support for using Ansible to configure Vagrant machines.

Tip

A full treatment of Vagrant is out of scope of this book. For more information, check out Vagrant: Up and Running, authored by Mitchell Hashimoto, the creator of Vagrant.

Convenient Vagrant Configuration Options

Vagrant exposes many configuration options for virtual machines, but there are two that I find particularly useful when using Vagrant for testing: setting a specific IP address and enabling agent forwarding.

Port Forwarding and Private IP Addresses

When you create a new Vagrantfile using the vagrant init command, the default networking configuration allows you to ...

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