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<div class="section" id="best-practices">
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<h1>Best Practices<a class="headerlink" href="#best-practices" title="Permalink to this headline">¶</a></h1>
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<p>Here are some tips for making the most of Ansible.</p>
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<div class="section" id="group-by-roles">
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<h2>Group By Roles<a class="headerlink" href="#group-by-roles" title="Permalink to this headline">¶</a></h2>
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<p>A system can be in multiple groups. See ref:<cite>patterns</cite>. Having groups named after things like
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‘webservers’ and ‘dbservers’ is repeated in the examples because it’s a very powerful concept.</p>
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<p>This allows playbooks to target machines based on role, as well as to assign role specific variables
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using the group variable system.</p>
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</div>
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<div class="section" id="directory-organization">
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<h2>Directory Organization<a class="headerlink" href="#directory-organization" title="Permalink to this headline">¶</a></h2>
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<p>Playbooks should be organized like this:</p>
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<div class="highlight-python"><pre>(root of source control repository)
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acme/ # each playbook has a directory
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setup.yml # playbook to manage the service
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stop.yml # playbook to halt the service (optional)
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files/
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some_file_path_foo.conf
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templates/
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etc_acme_conf_acme.conf
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etc_other_conf_other.conf
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vars/
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main.yml
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handlers/
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main.yml
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tasks/
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setup.yml
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stop.yml</pre>
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</div>
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<p>Any directories or files not needed can be omitted. Not all modules may require <cite>vars</cite> or <cite>files</cite> sections, though most
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will require <cite>handlers</cite>, <cite>tasks</cite>, and <cite>templates</cite>. To review what each of these sections do, see ref:<cite>playbooks</cite> and ref:<cite>playbooks2</cite>.</p>
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<p>The acme/setup.yml playbook would be as simple as:</p>
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<div class="highlight-python"><pre>----
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- hosts: webservers
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user: root
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vars_files
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- include: vars/main.yml
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tasks:
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- include: tasks/setup.yml
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handlers:
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- include: handlers/main.yml</pre>
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</div>
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<p>The tasks are individually broken out in ‘acme/tasks/setup.yml’, and handlers, which are common to all task files,
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are contained in ‘acme/handlers/main.yml’. As a reminder, handlers are mostly just used to notify services to restart
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when things change, and these are described in ref:<cite>playbooks</cite>.</p>
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<p>Including more than one setup file or more than one handlers file is of course legal.</p>
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<p>Having playbooks be able to include other playbooks is coming in release 0.5.</p>
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<p>Until then, to manage your entire site, simply execute all of your playbooks together, in the order desired.
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You don’t have to do this though, it’s fine to select sections of your infrastructure to manage at a single time.
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You may wish to construct simple shell scripts to wrap calls to ansible-playbook.</p>
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</div>
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<div class="section" id="miscellaneous-tips">
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<h2>Miscellaneous Tips<a class="headerlink" href="#miscellaneous-tips" title="Permalink to this headline">¶</a></h2>
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<p>When you can do something simply, do something simply. Do not reach to use every feature of Ansible together, all
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at once. Use what works for you. For example, you should probably not need ‘vars’, ‘vars_files’, ‘vars_prompt’ and ‘–extra-vars’ all at once, while also using an external inventory file.</p>
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<p>Optimize for readability. Whitespace between sections of YAML documents and in between tasks is strongly encouraged,
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as is usage of YAML comments, which start with “#”. It is also useful to comment at the top of each file the purpose of the individual file and the author, including email address.</p>
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<p>It is possible to leave off the “name” for a given task, though it is recommended to provide
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a descriptive comment about why something is being done instead.</p>
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<p>Use version control. Keep your playbooks and inventory file in git (or another version control system), and commit when you make changes to them.
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This way you have an audit trail describing when and why you changed the rules automating your infrastructure.</p>
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<p>Resist the urge to write the same playbooks and configuration files for heterogeneous distributions. While lots of software packages claim to make this easy on you, the configuration files are often quite different, to the point where it would be easier to treat them as different playbooks. This is why, for example, Ansible has a seperate ‘yum’ and ‘apt’ module. Yum and apt have different capabilities, and we don’t want to code for the least common denominator.</p>
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<p>Use variables for user tunable settings versus having constants in the tasks file or templates, so that it is easy to reconfigure a playbook. Think about this as exposing the knobs to things you would like to tweak.</p>
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<p>Since a system can be in more than one group, if you have multiple datacenters or sites, consider putting systems into groups by role, but also different groups by geography. This allows you to assign different variables to different geographies.</p>
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<div class="admonition-see-also admonition seealso">
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<p class="first admonition-title">See also</p>
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<dl class="last docutils">
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<dt><a class="reference internal" href="YAMLSyntax.html"><em>YAML Syntax</em></a></dt>
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<dd>Learn about YAML syntax</dd>
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<dt><a class="reference internal" href="playbooks.html"><em>Playbooks</em></a></dt>
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<dd>Review the basic playbook features</dd>
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<dt><a class="reference internal" href="modules.html"><em>Ansible Modules</em></a></dt>
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<dd>Learn about available modules</dd>
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<dt><a class="reference internal" href="moduledev.html"><em>Module Development</em></a></dt>
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<dd>Learn how to extend Ansible by writing your own modules</dd>
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<dt><a class="reference internal" href="patterns.html"><em>Inventory & Patterns</em></a></dt>
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<dd>Learn about how to select hosts</dd>
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<dt><a class="reference external" href="https://github.com/ansible/ansible/tree/master/examples/playbooks">Github examples directory</a></dt>
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<dd>Complete playbook files from the github project source</dd>
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<dt><a class="reference external" href="http://groups.google.com/group/ansible-project">Mailing List</a></dt>
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<dd>Questions? Help? Ideas? Stop by the list on Google Groups</dd>
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</dl>
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© Copyright 2012 Michael DeHaan.<br/>
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Last updated on May 13, 2012.<br/>
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