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< div class = "section" id = "best-practices" >
< h1 > Best Practices< a class = "headerlink" href = "#best-practices" title = "Permalink to this headline" > ¶< / a > < / h1 >
< p > Here are some tips for making the most of Ansible.< / p >
< div class = "section" id = "always-mention-state" >
< h2 > Always Mention State< a class = "headerlink" href = "#always-mention-state" title = "Permalink to this headline" > ¶< / a > < / h2 >
< p > The ‘ state’ parameter is optional to a lot of modules. Whether
‘ state=present’ or ‘ state=absent’ , it’ s always best to leave that
parameter in your playbooks to make it clear, especially as some
modules support additional states.< / p >
< / div >
< div class = "section" id = "group-by-roles" >
< h2 > Group By Roles< a class = "headerlink" href = "#group-by-roles" title = "Permalink to this headline" > ¶< / a > < / h2 >
< p > A system can be in multiple groups. See < a class = "reference internal" href = "patterns.html" > < em > Inventory & Patterns< / em > < / a > . Having groups named after things like
< em > webservers< / em > and < em > dbservers< / em > is repeated in the examples because it’ s a very powerful concept.< / p >
< p > This allows playbooks to target machines based on role, as well as to assign role specific variables
using the group variable system.< / p >
< / div >
< div class = "section" id = "directory-organization" >
< h2 > Directory Organization< a class = "headerlink" href = "#directory-organization" title = "Permalink to this headline" > ¶< / a > < / h2 >
< p > Playbooks should be organized like this:< / p >
< div class = "highlight-python" > < pre > # root of source control repository
├── acme/
│ ├── setup.yml
│ └── stop.yml
├── files/
│ └── some_file_path_foo.conf
├── handlers/
│ └── main.yml
├── tasks/
│ ├── setup.yml
│ └── stop.yml
├── templates/
│ ├── etc_acme_conf_acme.conf
│ └── etc_other_conf_other.conf
├── vars/
│ └── main.yml
└── global_vars.yml< / pre >
< / div >
< p > Any directories or files not needed can be omitted. Not all modules
may require ‘ vars’ or ‘ files’ sections, though most will require
‘ handlers’ , ‘ tasks’ , and ‘ templates’ . To review what each of
these sections do, see < a class = "reference internal" href = "playbooks.html" > < em > Playbooks< / em > < / a > and < a class = "reference internal" href = "playbooks2.html" > < em > Advanced Playbooks< / em > < / a > .< / p >
< p > The acme/setup.yml playbook would be as simple as:< / p >
< div class = "highlight-python" > < pre > ---
- hosts: webservers
user: root
vars_files:
- ../global_vars.yml
- vars/main.yml
tasks:
- include: tasks/setup.yml
handlers:
- include: handlers/main.yml< / pre >
< / div >
< p > The tasks are individually broken out in ‘ acme/tasks/setup.yml’ , and handlers, which are common to all task files,
are contained in ‘ acme/handlers/main.yml’ . As a reminder, handlers are mostly just used to notify services to restart
when things change, and these are described in < a class = "reference internal" href = "playbooks.html" > < em > Playbooks< / em > < / a > .< / p >
< p > Including more than one setup file or more than one handlers file is of course legal.< / p >
< p > Having playbooks be able to include other playbooks is coming in a
future release. See < a class = "reference external" href = "https://github.com/ansible/ansible/issues/538" > Issue 538< / a > .< / p >
< p > Until then, to manage your entire site, simply execute all of your playbooks together, in the order desired.
You don’ t have to do this though. It’ s fine to select sections of your infrastructure to manage at a single time.
You may wish to construct simple shell scripts to wrap calls to ansible-playbook.< / p >
< / div >
< div class = "section" id = "bundling-ansible-modules-with-playbooks" >
< h2 > Bundling Ansible Modules With Playbooks< a class = "headerlink" href = "#bundling-ansible-modules-with-playbooks" title = "Permalink to this headline" > ¶< / a > < / h2 >
< p class = "versionadded" >
< span class = "versionmodified" > New in version 0.5.< / span > < / p >
< p > If a playbook has a ” ./library” directory relative to it’ s YAML file,
this directory can be used to add ansible modules that will
automatically be in the ansible module path. This is a great way to
keep modules that go with a playbook together.< / p >
< / div >
< div class = "section" id = "miscellaneous-tips" >
< h2 > Miscellaneous Tips< a class = "headerlink" href = "#miscellaneous-tips" title = "Permalink to this headline" > ¶< / a > < / h2 >
< p > When you can do something simply, do something simply. Do not reach
to use every feature of Ansible together, all 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 >
< p > Optimize for readability. Whitespace between sections of YAML
documents and in between tasks is strongly encouraged, 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 >
< p > It is possible to leave off the ‘ name’ for a given task, though it
is recommended to provide a descriptive comment about why something is
being done instead.< / p >
< 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. This way you have an audit trail describing when and why you
changed the rules automating your infrastructure.< / p >
< 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
separate < a class = "reference internal" href = "modules.html#yum" > < em > yum< / em > < / a > and < a class = "reference internal" href = "modules.html#apt" > < em > apt< / em > < / a > module. Yum and apt have different
capabilities, and we don’ t want to code for the least common
denominator.< / p >
< 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 >
< 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 >
< div class = "admonition-see-also admonition seealso" >
< p class = "first admonition-title" > See also< / p >
< dl class = "last docutils" >
< dt > < a class = "reference internal" href = "YAMLSyntax.html" > < em > YAML Syntax< / em > < / a > < / dt >
< dd > Learn about YAML syntax< / dd >
< dt > < a class = "reference internal" href = "playbooks.html" > < em > Playbooks< / em > < / a > < / dt >
< dd > Review the basic playbook features< / dd >
< dt > < a class = "reference internal" href = "modules.html" > < em > Ansible Modules< / em > < / a > < / dt >
< dd > Learn about available modules< / dd >
< dt > < a class = "reference internal" href = "moduledev.html" > < em > Module Development< / em > < / a > < / dt >
< dd > Learn how to extend Ansible by writing your own modules< / dd >
< dt > < a class = "reference internal" href = "patterns.html" > < em > Inventory & Patterns< / em > < / a > < / dt >
< dd > Learn about how to select hosts< / dd >
< dt > < a class = "reference external" href = "https://github.com/ansible/ansible/tree/devel/examples/playbooks" > Github examples directory< / a > < / dt >
< dd > Complete playbook files from the github project source< / dd >
< dt > < a class = "reference external" href = "http://groups.google.com/group/ansible-project" > Mailing List< / a > < / dt >
< dd > Questions? Help? Ideas? Stop by the list on Google Groups< / dd >
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