Add fallback on the default system version of Python

smortex · smortex · commit 9ad7d6758197 · 2025-04-24T12:00:02.000-10:00
When Python is not installed, the python_version fact is undef, but we
need to know which version of Python is going to be installed by the
module in order to use the proper command invocation for building
virtual envs.

This issue only occurs when the user use the system version of Python,
so add the default version of Python for supported operating systems
into Hiera and use that as a fallback when the version of Python is
unknown.
diff --git a/REFERENCE.md b/REFERENCE.md
@@ -67,6 +67,7 @@ class { 'python' :
 
 The following parameters are available in the `python` class:
 
+* [`default_system_version`](#-python--default_system_version)
 * [`ensure`](#-python--ensure)
 * [`version`](#-python--version)
 * [`pip`](#-python--pip)
@@ -92,6 +93,12 @@ The following parameters are available in the `python` class:
 * [`anaconda_installer_url`](#-python--anaconda_installer_url)
 * [`anaconda_install_path`](#-python--anaconda_install_path)
 
+##### <a name="-python--default_system_version"></a>`default_system_version`
+
+Data type: `Python::Version`
+
+The default version of Python provided by the operating system. Only used as a fallback if Python is not installed yet to determine how to handle some actions that vary depending on the Python version used.
+
 ##### <a name="-python--ensure"></a>`ensure`
 
 Data type: `Python::Package::Ensure`
diff --git a/data/common.yaml b/data/common.yaml
@@ -0,0 +1 @@
+python::default_system_version: "3.11"
diff --git a/data/os/Archlinux.yaml b/data/os/Archlinux.yaml
@@ -0,0 +1 @@
+python::default_system_version: "3.13"
diff --git a/data/os/Debian/11.yaml b/data/os/Debian/11.yaml
@@ -0,0 +1 @@
+python::default_system_version: "3.9"
diff --git a/data/os/Debian/12.yaml b/data/os/Debian/12.yaml
@@ -0,0 +1 @@
+python::default_system_version: "3.11"
diff --git a/data/os/FreeBSD.yaml b/data/os/FreeBSD.yaml
@@ -0,0 +1 @@
+python::default_system_version: "3.11"
diff --git a/data/os/Gentoo.yaml b/data/os/Gentoo.yaml
@@ -0,0 +1 @@
+python::default_system_version: "3.12"
diff --git a/data/os/RedHat/8.yaml b/data/os/RedHat/8.yaml
@@ -0,0 +1 @@
+python::default_system_version: "3.6"
diff --git a/data/os/RedHat/9.yaml b/data/os/RedHat/9.yaml
@@ -0,0 +1 @@
+python::default_system_version: "3.9"
diff --git a/data/os/Ubuntu/20.04.yaml b/data/os/Ubuntu/20.04.yaml
@@ -0,0 +1 @@
+python::default_system_version: "3.8"
diff --git a/data/os/Ubuntu/22.04.yaml b/data/os/Ubuntu/22.04.yaml
@@ -0,0 +1 @@
+python::default_system_version: "3.10"
diff --git a/data/os/Ubuntu/24.04.yaml b/data/os/Ubuntu/24.04.yaml
@@ -0,0 +1 @@
+python::default_system_version: "3.12"
diff --git a/hiera.yaml b/hiera.yaml
@@ -0,0 +1,23 @@
+---
+version: 5
+
+defaults:               # Used for any hierarchy level that omits these keys.
+  datadir: data         # This path is relative to hiera.yaml's directory.
+  data_hash: yaml_data  # Use the built-in YAML backend.
+
+hierarchy:
+  - name: "archicture"
+    paths:
+      - "architecture/%{facts.os.architecture}.yaml"
+      - "architecture/common.yaml"
+  - name: "osfamily/major release"
+    paths:
+      - "os/%{facts.os.name}/%{facts.os.release.major}.yaml"   # Used to distinguish between Debian and Ubuntu
+      - "os/%{facts.os.family}/%{facts.os.release.major}.yaml" #
+      - "os/%{facts.os.family}/%{facts.kernelrelease}.yaml"    # Used for Solaris
+  - name: "osfamily"
+    paths:
+      - "os/%{facts.os.name}.yaml"
+      - "os/%{facts.os.family}.yaml"
+  - name: 'common'
+    path: 'common.yaml'
diff --git a/manifests/init.pp b/manifests/init.pp
@@ -1,5 +1,6 @@
 # @summary Installs and manages python, python-dev and gunicorn.
 #
+# @param default_system_version The default version of Python provided by the operating system. Only used as a fallback if Python is not installed yet to determine how to handle some actions that vary depending on the Python version used.
 # @param ensure Desired installation state for the Python package.
 # @param version Python version to install. Beware that valid values for this differ a) by the provider you choose and b) by the osfamily/operatingsystem you are using.
 #  Allowed values:
@@ -38,6 +39,7 @@
 #   }
 #
 class python (
+  Python::Version            $default_system_version,
   Python::Package::Ensure    $ensure                      = 'present',
   Python::Version            $version                     = $facts['os']['family'] ? { 'Archlinux' => 'system', default => '3' },
   Python::Package::Ensure    $pip                         = 'present',
diff --git a/manifests/pyvenv.pp b/manifests/pyvenv.pp
@@ -41,7 +41,7 @@
 
   if $ensure == 'present' {
     $python_version = $version ? {
-      'system' => $facts['python3_version'],
+      'system' => $facts['python3_version'].lest || { $python::default_system_version },
       default  => $version,
     }
 
