From 6359cfbe02d1f5882f98a9629c4dd1536807d8b9 Mon Sep 17 00:00:00 2001
From: Steve Traylen <steve.traylen@cern.ch>
Date: Thu, 11 Jul 2019 16:46:28 +0200
Subject: [PATCH] Accept to use python3 if python is not on the path

RHEL8 in particular has no python command by design
attempt to use python3 if there is no python command.

https://developers.redhat.com/blog/2018/11/14/python-in-rhel-8/
---
 README.md                    |  4 ++--
 lib/facter/python_dir.rb     |  6 ++++++
 spec/unit/python_dir_spec.rb | 13 +++++++++++++
 3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 8e7e040f2..9dbe10c3f 100644
--- a/README.md
+++ b/README.md
@@ -1453,8 +1453,8 @@ class { 'collectd::plugin::protocols':
 
 #### Class: `collectd::plugin::python`
 The plugin uses a fact `python_dir` to find the python load path for modules.
-python must be installed as a pre-requisite for the this fact to give a
-non-default value.
+python or python3 must be installed as a pre-requisite for the this
+fact to give a non-default value.
 
 * `modulepaths` is an array of paths where will be Collectd looking for Python
   modules, Puppet will ensure that each of specified directories exists and it
diff --git a/lib/facter/python_dir.rb b/lib/facter/python_dir.rb
index 7c2b00064..c6beaf66b 100644
--- a/lib/facter/python_dir.rb
+++ b/lib/facter/python_dir.rb
@@ -10,6 +10,12 @@
       else
         Facter::Util::Resolution.exec('python -c "import site; print(site.getsitepackages()[0])"')
       end
+    elsif Facter::Util::Resolution.which('python3')
+      if Facter.value(:osfamily) == 'RedHat'
+        Facter::Util::Resolution.exec('python3 -c "from distutils.sysconfig import get_python_lib; print(get_python_lib())"')
+      else
+        Facter::Util::Resolution.exec('python3 -c "import site; print(site.getsitepackages()[0])"')
+      end
     else
       ''
     end
diff --git a/spec/unit/python_dir_spec.rb b/spec/unit/python_dir_spec.rb
index a7ebfb0c9..b0deaf8da 100644
--- a/spec/unit/python_dir_spec.rb
+++ b/spec/unit/python_dir_spec.rb
@@ -26,10 +26,23 @@
         expect(Facter.value(:python_dir)).to eq('/usr/lib/python2.7/site-packages')
       end
     end
+
+    context 'RedHat versioned python' do
+      before do
+        Facter.fact(:osfamily).stubs(:value).returns('RedHat')
+        Facter::Util::Resolution.stubs(:which).with('python').returns(false)
+        Facter::Util::Resolution.stubs(:which).with('python3').returns(true)
+        Facter::Util::Resolution.stubs(:exec).with('python3 -c "from distutils.sysconfig import get_python_lib; print(get_python_lib())"').returns('/usr/lib/python3.6/site-packages')
+      end
+      it do
+        expect(Facter.value(:python_dir)).to eq('/usr/lib/python3.6/site-packages')
+      end
+    end
   end
 
   it 'is empty string if python not installed' do
     Facter::Util::Resolution.stubs(:which).with('python').returns(nil)
+    Facter::Util::Resolution.stubs(:which).with('python3').returns(nil)
     expect(Facter.fact(:python_dir).value).to eq('')
   end
 end