From 4dbfab66a13d6e0568133c5fe349a719167017fa Mon Sep 17 00:00:00 2001
From: Ian Wienand <iwienand@redhat.com>
Date: Mon, 20 Jul 2020 14:01:10 +1000
Subject: [PATCH] Pre-install python3 for CentOS

CentOS 7 is the only distro we support currently that doesn't have
Python 3 installed in some form in the base images.  For centos 7 add
an early install of it in the yum element so we can have all the
in-chroot scripts assume Python 3.  There is only one package that
causes issues; yaml which comes from EPEL.  Everywhere else it is a
base package, but we don't have a way to say "enable epel to install
this".  Just hack it in, we don't want to go reworking the world for
CentOS 7 at this point.

Also add python3 and it's yaml library to the centos 8 path.  This
brings in the "user" python3 in /urs/bin/python3 (the "system" python3
is already installed).  Again, this just lets us assume
/usr/bin/python3 in scripts for all platforms.

package-installs is one of these things running python in the chroot,
and unfortunately we have elements that use it at 01- level in
pre-installd.  Thus to make sure python3 is there nice and early, run
it at 0 level, but make sure it comes after yum/dnf update.

Change-Id: I088fc4284e889147ca9a375d4a159264cff53484
---
 ...2-package-installs => 10-package-installs} |  0
 .../{00-dnf-update => 00-0-dnf-update}        |  0
 .../yum/pre-install.d/00-1-centos-python3     | 25 +++++++++++++++++++
 3 files changed, 25 insertions(+)
 rename diskimage_builder/elements/package-installs/pre-install.d/{02-package-installs => 10-package-installs} (100%)
 rename diskimage_builder/elements/yum/pre-install.d/{00-dnf-update => 00-0-dnf-update} (100%)
 create mode 100755 diskimage_builder/elements/yum/pre-install.d/00-1-centos-python3

diff --git a/diskimage_builder/elements/package-installs/pre-install.d/02-package-installs b/diskimage_builder/elements/package-installs/pre-install.d/10-package-installs
similarity index 100%
rename from diskimage_builder/elements/package-installs/pre-install.d/02-package-installs
rename to diskimage_builder/elements/package-installs/pre-install.d/10-package-installs
diff --git a/diskimage_builder/elements/yum/pre-install.d/00-dnf-update b/diskimage_builder/elements/yum/pre-install.d/00-0-dnf-update
similarity index 100%
rename from diskimage_builder/elements/yum/pre-install.d/00-dnf-update
rename to diskimage_builder/elements/yum/pre-install.d/00-0-dnf-update
diff --git a/diskimage_builder/elements/yum/pre-install.d/00-1-centos-python3 b/diskimage_builder/elements/yum/pre-install.d/00-1-centos-python3
new file mode 100755
index 00000000..f39d2542
--- /dev/null
+++ b/diskimage_builder/elements/yum/pre-install.d/00-1-centos-python3
@@ -0,0 +1,25 @@
+#!/bin/bash
+
+if [ ${DIB_DEBUG_TRACE:-0} -gt 0 ]; then
+    set -x
+fi
+set -eu
+set -o pipefail
+
+# Ensure the python3 interpreter and YAML libraries are installed
+# early (even before package-installs, which is written in Python and
+# uses YAML).
+
+if [[ ${DISTRO_NAME} =~ (centos|rhel) && ${DIB_RELEASE} == 7 ]]; then
+    # Our package map and install stuff doesn't have a way to say
+    # "install this from EPEL".  So we hack in an install of it here
+    # from EPEL.  Nothing else should have installed EPEL at this
+    # early stage.
+    yum install -y python3 epel-release
+    yum install -y python36-PyYAML
+    yum remove -y epel-release
+elif [[ ${DISTRO_NAME} =~ (centos|rhel) && ${DIB_RELEASE} > 7 ]]; then
+    # For 8 and above ensure the "user" python3 package is installed
+    # so we have /usr/bin/python3 and pyyaml.
+    dnf install -y python3 python3-pyyaml
+fi