replace 'distro_python3' variable with 'distro_python_version'

RHEL7 derived distros use Python 2.7
RHEL8 uses Python 3.6
Ubuntu 18.04 uses Python 3.6, but we haven't enabled it yet.
Debian:buster uses Python 3.7, but we haven't enabled it yet.

We have several places in code where "/lib/pythonX.Y/site-packages"
is used so we need to know value of X.Y rather than py2/py3 switch.

How to check for Python 2:

{% if distro_python_version == '2.7' %}

Breaks: Iad6b70b433a0dd1b0f8ae6790fd280594517661a
Change-Id: Ie24f109af19ae0438c21e0d43cb3cc947812b4ce

3 files changed, 38 insertions, 21 deletions

diff --git a/kolla/common/config.py b/kolla/common/config.py
index 5d1082f65..05ccb13e0 100755
--- a/kolla/common/config.py
+++ b/kolla/common/config.py
@@ -266,10 +266,6 @@ _BASE_OPTS = [
     cfg.StrOpt('maintainer',
                default='Kolla Project (https://launchpad.net/kolla)',
                help='Content of the maintainer label'),
-    cfg.BoolOpt('distro_python3', default=None,
-                help=('Enable this to force python3 packaging names. By '
-                      'default this will try and determine the value of this '
-                      'based on the base_distro and base_distro_tag.')),
     cfg.StrOpt('base_package_type', default=None,
                help=('Set the package type of the distro. If not set then '
                      'the packaging type is set to "rpm" if a RHEL based '
diff --git a/kolla/image/build.py b/kolla/image/build.py
index 0306d9b2b..624db3406 100755
--- a/kolla/image/build.py
+++ b/kolla/image/build.py
@@ -693,13 +693,13 @@ class KollaWorker(object):
         deb_base = ['ubuntu', 'debian']
         deb_type = ['source', 'binary']
 
-        if self.conf.distro_python3 is not None:
-            self.distro_python3 = self.conf.distro_python3
-        elif self.base in rh_base and self.base_tag in ['8']:
-            # RHEL 8+ is python3
-            self.distro_python3 = True
+        if self.base in rh_base and self.base_tag.startswith('7'):
+            self.conf.distro_python_version = "2.7"
+        elif self.base in rh_base and self.base_tag.startswith('8'):
+            self.conf.distro_python_version = "3.6"
         else:
-            self.distro_python3 = False
+            # Assume worst
+            self.conf.distro_python_version = "2.7"
 
         # Determine base packaging type for use in Dockerfiles.
         if self.conf.base_package_type:
@@ -738,6 +738,7 @@ class KollaWorker(object):
         self.image_statuses_unmatched = dict()
         self.image_statuses_skipped = dict()
         self.maintainer = conf.maintainer
+        self.distro_python_version = conf.distro_python_version
 
         docker_kwargs = docker.utils.kwargs_from_env()
         try:
@@ -915,7 +916,7 @@ class KollaWorker(object):
                       'kolla_version': kolla_version,
                       'image_name': image_name,
                       'users': self.get_users(),
-                      'distro_python3': self.distro_python3,
+                      'distro_python_version': self.distro_python_version,
                       'rpm_setup': self.rpm_setup,
                       'build_date': build_date}
             env = jinja2.Environment(  # nosec: not used to render HTML
diff --git a/kolla/tests/test_build.py b/kolla/tests/test_build.py
index 6ed50fbf1..32c5a9928 100644
--- a/kolla/tests/test_build.py
+++ b/kolla/tests/test_build.py
@@ -381,25 +381,45 @@ class KollaWorkerTest(base.TestCase):
         kolla = build.KollaWorker(self.conf)
         self.assertEqual(2, len(kolla.rpm_setup))
 
-    def test_build_distro_python3(self):
-        """check distro_python3 conf value is taken"""
-        self.conf.set_override('distro_python3', True)
+    def test_build_distro_python_version_debian(self):
+        """check distro_python_version for Debian"""
+        self.conf.set_override('base', 'debian')
+        kolla = build.KollaWorker(self.conf)
+        self.assertEqual('2.7', kolla.distro_python_version)
+
+    def test_build_distro_python_version_rhel80(self):
+        """check distro_python_version for RHEL8.0"""
+        self.conf.set_override('base', 'rhel')
+        self.conf.set_override('base_tag', '8.0')
         kolla = build.KollaWorker(self.conf)
-        self.assertTrue(kolla.distro_python3)
+        self.assertEqual('3.6', kolla.distro_python_version)
 
-    def test_build_distro_python3_rhel8(self):
-        """check distro_python3 true for rhel8"""
+    def test_build_distro_python_version_rhel8(self):
+        """check distro_python_version for RHEL8"""
         self.conf.set_override('base', 'rhel')
         self.conf.set_override('base_tag', '8')
         kolla = build.KollaWorker(self.conf)
-        self.assertTrue(kolla.distro_python3)
+        self.assertEqual('3.6', kolla.distro_python_version)
+
+    def test_build_distro_python_version_ubuntu(self):
+        """check distro_python_version for Ubuntu"""
+        self.conf.set_override('base', 'ubuntu')
+        kolla = build.KollaWorker(self.conf)
+        self.assertEqual('2.7', kolla.distro_python_version)
+
+    def test_build_distro_python_version_centos7(self):
+        """check distro_python_version for CentOS 7.6.1810"""
+        self.conf.set_override('base', 'centos')
+        self.conf.set_override('base_tag', '7.6.1810')
+        kolla = build.KollaWorker(self.conf)
+        self.assertEqual('2.7', kolla.distro_python_version)
 
-    def test_build_distro_python3_non_rhel8(self):
-        """check distro_python3 false for non-rhel8"""
+    def test_build_distro_python_version_rhel7(self):
+        """check distro_python_version for RHEL7"""
         self.conf.set_override('base', 'rhel')
         self.conf.set_override('base_tag', '7')
         kolla = build.KollaWorker(self.conf)
-        self.assertFalse(kolla.distro_python3)
+        self.assertEqual('2.7', kolla.distro_python_version)
 
     def test_base_package_type(self):
         """check base_package_type conf value is taken"""