79 lines
2.5 KiB
ReStructuredText
79 lines
2.5 KiB
ReStructuredText
.. _virtual-environments:
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====================
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Virtual Environments
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====================
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Python `virtual environments <https://virtualenv.pypa.io/en/stable/>`_ provide
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a mechanism for isolating python packages from the system site packages, and
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other virtual environments. Kolla-ansible largely avoids this problem by
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deploying services in Docker containers, however some python dependencies must
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be installed both on the Ansible control host and the target hosts.
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Ansible Control Host
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====================
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The kolla-ansible python package and its dependencies may be installed in a
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python virtual environment on the Ansible control host. For example:
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.. code-block:: console
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virtualenv /path/to/venv
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source /path/to/venv/bin/activate
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pip install -U pip
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pip install kolla-ansible
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deactivate
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It may be advantageous to also install Ansible in the virtual environment.
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.. code-block:: console
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source /path/to/venv/bin/activate
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(venv) pip install ansible
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(venv) deactivate
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To use the virtual environment, it should first be activated:
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.. code-block:: console
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source /path/to/venv/bin/activate
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(venv) kolla-ansible --help
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The virtual environment can be deactivated when necessary:
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.. code-block:: console
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(venv) deactivate
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Note that the use of a virtual environment on the Ansible control host does not
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imply that a virtual environment will be used for execution of Ansible modules
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on the target hosts.
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.. _virtual-environments-target-hosts:
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Target Hosts
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============
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Ansible supports remote execution of modules in a python virtual environment
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via the ``ansible_python_interpreter`` variable. This may be configured to be
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the path to a python interpreter installed in a virtual environment. For
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example:
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.. code-block:: yaml
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ansible_python_interpreter: /path/to/venv/bin/python
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Note that ``ansible_python_interpreter`` cannot be templated.
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Kolla-ansible provides support for creating a python virtual environment on the
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target hosts as part of the ``bootstrap-servers`` command. The path to the
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virtualenv is configured via the ``virtualenv`` variable, and access to
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site-packages is controlled via ``virtualenv_site_packages``. Typically we
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will need to enable use of system site-packages from within this virtualenv, to
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support the use of modules such as yum, apt, and selinux, which are not
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available on PyPI.
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When executing kolla-ansible commands other than ``bootstrap-servers``, the
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variable ``ansible_python_interpreter`` should be set to the python interpreter
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installed in ``virtualenv``.
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