Merge "Add support to use stow for ensure-python"

roles/ensure-python/README.rst

@@ -3,14 +3,40 @@ Ensure specified python interpreter and development files are installed
 .. note:: This role is only available for Debian based platforms
           currently.
 
+There are three ways to install the python interpreter:
+
+1. Using distribution packages: This is the default (``python_use_pyenv`` and
+   ``python_use_stow`` are both false``).
+
+2. Install using ``pyenv``.
+
+3. Install using ``stow``.
+
+.. note:: You cannot use both ``pyenv`` and ``stow`` method for the same job.
+          That means that ``python_use_pyenv`` and ``python_use_stow``
+          cannot be set both to ``True`` at the same time.
+
 **Role Variables**
 
 .. zuul:rolevar:: python_version
 
-  Optional version of python interpreter to install, such as ``3.7``.
+   Optional version of python interpreter to install, such as ``3.7``.
 
 .. zuul:rolevar:: python_use_pyenv
    :default: False
 
-   Whether to optionally use pyenv to install python instead of distro
+   Whether to optionally use ``pyenv`` to install python instead of distro
    packages.
+
+.. zuul:rolevar:: python_use_stow
+   :default: False
+
+   In case you have image with already prepared python versions, for example used the
+   python-stow-versions element, you can activate them with stow utility
+   by setting this variable to ``true``.
+
+.. zuul:rolevar:: python_stow_dir
+   :default: /usr/local/stow
+
+   Sets the target directory for stow. This should be the path to the
+   directory where prepared python packages are located.

roles/ensure-python/defaults/main.yaml

@@ -1 +1,3 @@
 python_use_pyenv: false
+python_use_stow: false
+python_stow_dir: /usr/local/stow

roles/ensure-python/tasks/main.yaml

@@ -11,6 +11,7 @@
     - python_version is defined
     - ansible_distribution == 'Debian' or ansible_distribution == 'Ubuntu'
     - not python_use_pyenv
+    - not python_use_stow
   package:
     name: python{{ python_version }}-dev
     state: present
@@ -21,3 +22,9 @@
     - python_version is defined
     - python_use_pyenv
   include_tasks: pyenv.yaml
+
+- name: Activate python using stow
+  when:
+    - python_version is defined
+    - python_use_stow
+  include_tasks: stow.yaml

roles/ensure-python/tasks/stow.yaml

@@ -0,0 +1,13 @@
+- name: Get stow environments
+  find:
+    paths: "{{ python_stow_dir }}"
+    recurse: no
+    file_type: directory
+  register: stow_envs
+
+- name: Activate stow
+  command: "stow -d {{ python_stow_dir }} -S {{ zj_stow_env | basename }}"
+  loop: "{{ stow_envs.files | map(attribute='path') | unique }}"
+  loop_control:
+    loop_var: zj_stow_env
+  when: python_version in item