Difference between revisions of "Ansible"
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[[wp:Ansible_(software)]] is an open-source software platform for configuring and managing computers. It combines multi-node software deployment, ad hoc task execution, and configuration management. Written in Python, it is packaged by [[RedHat]]. As of July 2016, we're using Ansible 2.2.0 | [[wp:Ansible_(software)]] is an open-source software platform for configuring and managing computers. It combines multi-node software deployment, ad hoc task execution, and configuration management. Written in Python, it is packaged by [[RedHat]]. As of July 2016, we're using Ansible 2.2.0 | ||
| + | == Installation == | ||
| + | The preferred way to [http://docs.ansible.com/intro_installation.html install] is to just <code>git clone</code> the source. Having the source makes it easy to upgrade, and it's self-contained, plus best of all you get all the examples and contribs. | ||
| + | If you see this error message: | ||
| + | <pre> | ||
| + | Traceback (most recent call last): | ||
| + | File "/usr/local/bin/ansible-playbook", line 44, in <module> | ||
| + | import ansible.constants as C | ||
| + | ImportError: No module named ansible.constants | ||
| + | </pre> | ||
| + | Be sure to source the env-setup script | ||
| + | |||
| + | == Getting Started == | ||
| + | You must source the environment setup script to begin using Ansible (assuming you are running from a git checkout) <code>source ~/bin/ansible/hacking/env-setup</code> | ||
Ansible provides three main commands: | Ansible provides three main commands: | ||
# <code>ansible-playbook</code> - to execute an Ansible playbook on the specified systems | # <code>ansible-playbook</code> - to execute an Ansible playbook on the specified systems | ||
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== Modules == | == Modules == | ||
Ansible comes with [https://docs.ansible.com/ansible/modules_by_category.html over 200 modules] that you should get familiar with in order to use the system effectively. | Ansible comes with [https://docs.ansible.com/ansible/modules_by_category.html over 200 modules] that you should get familiar with in order to use the system effectively. | ||
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| + | There are a bunch of modules in Ansible, like the [https://docs.ansible.com/ansible/mysql_db_module.html MySQL module], the [https://docs.ansible.com/ansible/monit_module.html Monit module], or the [https://docs.ansible.com/ansible/file_module.html File module] and other interesting modules like jabber, mail, sendgrid, dpkg_selections, composer, yum, redhat_subscription, the [https://docs.ansible.com/ansible/authorized_key_module.html authorized_key module] for working with SSH keys, and a whole section of [https://docs.ansible.com/ansible/list_of_system_modules.html system modules]. | ||
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| + | You can use the '''command module''' (secure but simple) or the '''[https://docs.ansible.com/ansible/shell_module.html shell module]'''. The latter may be useful if you need to run bash explicitly (defaults to /bin/sh); or anytime you need $HOME and redirection. | ||
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== Example Commands == | == Example Commands == | ||
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Ansible can deploy to virtualization environments and public and private cloud environments including VMWare, OpenStack, AWS, Eucalyptus Cloud, KVM, and CloudStack | Ansible can deploy to virtualization environments and public and private cloud environments including VMWare, OpenStack, AWS, Eucalyptus Cloud, KVM, and CloudStack | ||
| − | == | + | == Best Practices == |
| − | + | Use tags to organize your Ansible work | |
| − | < | + | |
| − | + | Use caching (default is off) to be able to refer to host 'facts' without having to hit each host in a playbook. | |
| − | + | ||
| − | + | Use register of [https://docs.ansible.com/ansible/playbooks_variables.html variables] to create more 'facts'. Results vary from module to module. Use -v to see possible values. | |
| − | + | ||
| − | </ | + | There is an order of precedence with [https://docs.ansible.com/ansible/playbooks_variables.html playbook variables], with role defaults the lowest priority and extra vars the winner. |
| − | + | ||
| + | The array notation is preferred over the dot notation for accessing variables. | ||
| + | {{ ansible_eth0["ipv4"]["address"] }} over {{ ansible_eth0.ipv4.address }} because some keywords in Python would conflict | ||
| + | |||
| + | Reserved words: | ||
| + | * hostvars | ||
| + | * group_names | ||
| + | * groups | ||
| + | * environemnt | ||
| + | |||
| + | '''inventory_hostname''' is the name of the . '''ansible_hostname''' is the discovered hostname | ||
| + | |||
| + | You can use a variables file to put sensitive data in a different file (one excluded from git). | ||
| + | <source lang="yaml"> | ||
| + | - hosts: all | ||
| + | remote_user: root | ||
| + | vars: | ||
| + | favcolor: blue | ||
| + | vars_files: | ||
| + | - /vars/top_secret.yml | ||
| + | </source> | ||
| + | |||
| + | You can use variables on the command line (and besides key=value pairs, you can use json or yml) | ||
| + | <source lang="yaml"> | ||
| + | --- | ||
| + | |||
| + | - hosts: '{{ hosts }}' | ||
| + | remote_user: '{{ user }}' | ||
| + | |||
| + | tasks: | ||
| + | - ... | ||
| + | </source> | ||
| + | <code>ansible-playbook release.yml --extra-vars "hosts=vipers user=starbuck"</code> | ||
| + | |||
| + | == Scope == | ||
| + | Ansible has 3 main scopes: | ||
| + | |||
| + | '''Global''': this is set by config, environment variables and the command line | ||
| + | '''Play''': each play and contained structures, vars entries, include_vars, role defaults and vars. | ||
| + | '''Host''': variables directly associated to a host, like inventory, facts or registered task outputs | ||
== Ansible with MediaWiki == | == Ansible with MediaWiki == | ||
Revision as of 23:37, 15 September 2016
- ↑ Choosing which host(s) to operate on https://docs.ansible.com/ansible/intro_patterns.html
