Allow the build to be done without the install tasks

In order to cater for the option of doing a build without
doing the installation tasks too (as one might do in CI),
a flag has been added.

defaults/main.yml

@@ -60,6 +60,10 @@ venv_pip_install_args: ""
 # re-use the venv in subsequent deployments.
 venv_reuse_enable: yes
 
+# Enable the ability to *only* do the build, so that
+# the deploy host can be pre-populated with the venvs.
+venv_reuse_build_only: no
+
 # The path where a built venv should be stored on the
 # deployment host. By default, ensure that the location
 # separates venvs per distribution and architecture to

tasks/main.yml

@@ -25,8 +25,10 @@
 - include_tasks: "python_venv_install.yml"
   when:
     - venv_reuse_enable | bool
+    - not venv_reuse_build_only | bool
     - _src_venv_present.stat.exists | bool
 
 - include_tasks: "python_venv_set_facts.yml"
   when:
+    - not venv_reuse_build_only | bool
     - venv_facts_when_changed != []

tasks/python_venv_preflight.yml

@@ -21,6 +21,17 @@
   when:
     - venv_destination_path is not defined
 
+- name: Verify that venv_reuse_enable and venv_reuse_build_only are not interfering with each other
+  fail:
+    msg: |
+      If venv_reuse_build_only is enabled, then venv_reuse_enable must also
+      be enabled.
+      The variable venv_reuse_enable is set to {{ venv_reuse_enable }}.
+      The variable venv_reuse_build_only is set to {{ venv_reuse_build_only }}.
+  when:
+    - venv_reuse_build_only | bool
+    - not venv_reuse_enable | bool
+
 - name: Ensure that venv_reuse_download_path exists on the deployment host
   file:
     path: "{{ venv_reuse_download_path }}"