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107 lines
2.8 KiB
Markdown
107 lines
2.8 KiB
Markdown
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# Auto Install Ansible roles
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*Author*: Will Thames <@willthames>
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*Date*: 19/02/2016
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## Motivation
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To use the latest (or even a specific) version of a playbook with the
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appropriate roles, the following steps are typically required:
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```
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git pull upstream branch
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ansible-galaxy install -r path/to/rolesfile.yml -p path/to/rolesdir -f
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ansible-playbook run-the-playbook.yml
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```
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The most likely step in this process to be forgotten is the middle step. While
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we can improve processes and documentation to try and ensure that this step is
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not skipped, we can improve ansible-playbook so that the step is not required.
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## Approaches
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### Approach 1: Specify rolesfile and rolesdir in playbook
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Provide new `rolesdir` and `rolesfile` keywords:
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```
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- hosts: application-env
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become: True
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rolesfile: path/to/rolesfile.yml
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rolesdir: path/to/rolesdir
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roles:
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- roleA
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- { role: roleB, tags: role_roleB }
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```
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Running ansible-playbook against such a playbook would cause the roles listed in
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`rolesfile` to be installed in `rolesdir`.
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Add new configuration to allow default rolesfile, default rolesdir and
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whether or not to auto update roles (defaulting to False)
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#### Advantages
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- Existing mechanism for roles management is maintained
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- Playbooks are not polluted with roles 'meta' information (version, source)
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#### Disadvantage
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- Adds two new keywords
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- Adds three new configuration variables for defaults
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### Approach 2: Allow rolesfile inclusion
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Allow the `roles` section to include a roles file:
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```
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- hosts: application-env
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become: True
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roles:
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- include: path/to/rolesfile.yml
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```
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Running this playbook would cause the roles to be updated from the included
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roles file.
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This would also be functionally equivalent to specifying the roles file
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content within the playbook:
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```
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- hosts: application-env
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become: True
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roles:
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- src: https://git.example.com/roleA.git
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scm: git
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version: 0.1
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- src: https://git.example.com/roleB.git
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scm: git
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version: 0.3
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tags: role_roleB
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```
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#### Advantages
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- The existing rolesfile mechanism is maintained
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- Uses familiar inclusion mechanism
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#### Disadvantage
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- Separate playbooks would need separate rolesfiles. For example, a provision
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playbook and upgrade playbook would likely have some overlap - currently
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you can use the same rolesfile with ansible-galaxy so that the same
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roles are available but only a subset of roles is used by the smaller
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playbook.
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- The roles file would need to be able to include playbook features such
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as role tagging.
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- New configuration defaults would likely still be required (and possibly
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an override keyword for rolesdir and role auto update)
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## Conclusion
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The author's preferred approach is currently Approach 1.
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Feedback is requested to improve either approach, or provide further
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approaches to solve this problem.
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