Mastering Ansible

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Chapter 1This command was piped into cat to prevent shell pagingfrom being used.Arguments can be templated with Jinja2, which will be parsed at module executiontime, allowing for data discovered in a previous task to be used in later tasks; this is avery powerful design element.[ 23 ]
System Architecture and Design of AnsibleArguments can be supplied in a key = value format, or in a complex format thatis more native to YAML. Here are two examples of arguments being passed to amodule showcasing the two formats:- name: add a keypair to novanova_keypair: login_password={{ pass }} login_tenant_name=adminname=admin-key- name: add a keypair to novanova_keypair: login_password: "{{ pass }}" login_tenant_name: adminname: admin-keyBoth formats will lead to the same result in this example; however, the complexformat is required if you wish to pass complex arguments into a module. Somemodules expect a list object or a hash of data to be passed in; the complex formatallows for this. While both formats are acceptable for many tasks, the complexformat is the format used for the majority of examples in this book.Module transport and executionOnce a module is found, Ansible has to execute it in some way. How the module istransported and executed depends on a few factors, however the common processis to locate the module file on the local filesystem and read it into memory, and thenadd in the arguments passed to the module. Finally, the boilerplate module codefrom core Ansible is added to complete the file object in memory. What happens nextreally depends on the connection method and runtime options (such as leaving themodule code on the remote system for review).The default connection method is smart, which most often resolves to the sshconnection method. With a default configuration, Ansible will open an SSHconnection to the remote host, create a temporary directory, and close the connection.Ansible will then open another SSH connection in order to write out the task objectfrom memory (the result of local module file, task module arguments, and Ansibleboilerplate code) into a file within the temporary directory that we just created andclose the connection.Finally, Ansible will open a third connection in order to execute the moduleand delete the temporary directory and all its contents. The module results arecaptured from stdout in the JSON format, which Ansible will parse and handleappropriately. If a task has an async control, Ansible will close the third connectionbefore the module is complete, and SSH back in to the host to check the status of thetask after a prescribed period until the module is complete or a prescribed timeouthas been reached.[ 24 ]
Page 1 and 2: [ 1 ]www.allitebooks.com
Page 3 and 4: Mastering AnsibleCopyright © 2015
Page 5 and 6: About the AuthorJesse Keating is an
Page 7 and 8: About the ReviewersRyan Eschinger i
Page 9 and 10: Patrik Uytterhoeven has over 16 yea
Page 12 and 13: Table of ContentsPrefaceviiChapter
Page 14 and 15: [ iii ]Table of ContentsPython obje
Page 16: Table of ContentsLookup plugins 193
Page 19 and 20: PrefaceChapter 7, Troubleshooting A
Page 21 and 22: PrefaceErrataAlthough we have taken
Page 23 and 24: System Architecture and Design of A
Page 43: System Architecture and Design of A
Page 55 and 56: Protecting Your Secrets with Ansibl
Page 70 and 71: Unlocking the Power ofJinja2 Templa
Page 72 and 73: Chapter 3Executing this playbook wi
Page 74 and 75: Chapter 3Changing the value of api.
Page 76 and 77: Chapter 3{% if dir != "/" %}data_di
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Controlling Task ConditionsAnsible
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Composing Reusable Ansible Content
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Now, let's execute the playbook aga
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Troubleshooting AnsibleAnsible is s
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Chapter 7Variable introspectionA co
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Chapter 7Running this modified play
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Using debug to display the entire c
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Chapter 7To discover the path to th
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Chapter 7The where and the list com
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My development system is a Mac lapt
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Chapter 7SummaryAnsible is software
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Extending AnsibleThe basic module c
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Extending AnsibleWith a module obje
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Extending AnsibleModule documentati
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included tasks, tagging 105, 106var
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Ansible ConfigurationManagementSeco
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