ansible: add Python 3 to centos7-arm64 hosts

Installs Python 3.8, enabled via `. /opt/rh/rh-python38/enable`.

Author: richardlau

ansible/roles/baselayout/vars/main.yml

@@ -40,7 +40,7 @@ packages: {
 
   # centos-release-scl is required to enable SCLo but we do it manually in
   # partials/repo/centos7.yml for arm64
-  centos7_arm64: ['git'], # git2u not available for aarch64 (yet)
+  centos7_arm64: ['git,rh-python38-python'], # git2u not available for aarch64 (yet)
   centos7_x64: ['devtoolset-6-libatomic-devel,git2u,centos-release-scl'],
   centos7_ppc64: ['cmake3,devtoolset-6-libatomic-devel,git,python3'],
 

jenkins/scripts/select-compiler.sh

@@ -167,6 +167,10 @@ elif [ "$SELECT_ARCH" = "X64" ]; then
 elif [ "$SELECT_ARCH" = "ARM64" ]; then
   echo "Setting compiler for Node version $NODEJS_MAJOR_VERSION on arm64"
 
+  if [ "$NODEJS_MAJOR_VERSION" -gt "13" ]; then
+    . /opt/rh/rh-python38/enable
+    echo "Enabled Python 3.8"
+  fi
 
   case $nodes in
     centos7-arm64-gcc8 )