From 63d25d978ba0a0cdb1b689cafcebdaae7d609e06 Mon Sep 17 00:00:00 2001
From: "Daniel P. Berrange" <berrange@redhat.com>
Date: Tue, 9 Dec 2014 15:21:22 +0000
Subject: [PATCH] Allow use of dnf instead of yum on Fedora

Since Fedora 20 it has been possible to use 'dnf' as a drop-in
replacement for 'yum', and it is targetted to become the default
in Fedora 22

   http://fedoraproject.org/wiki/Changes/ReplaceYumWithDNF

There are many benefits of 'dnf' over 'yum' but the biggest
from the POV of an openstack developer is its speed.

Assuming an existing running devstack install ie all required
RPMs already installed on the system. Now look at how long it
takes to run stack.sh, during which yum does not have to
actually install anything

 # ./unstack.sh
 # time ./stack.sh
 real 11m12.193s
 user 10m17.129s
 sys  0m15.275s

Now, with 'export YUM=dnf' set in local.conf, run the same
test again

 # ./unstack.sh
 # time ./stack.sh
 real 0m48.610s
 user 0m28.939s
 sys  0m7.801s

So, this is showing that devstack is wasting 10 minutes just
for yum to figure out that everything is already installed.
The overhead of yum vs dnf is even worse when yum has to
acutally depsolve to install new packages.

Change-Id: Ia01a5f330a47b32207586902a861bedfc8a0f6e2
---
 functions-common | 8 ++++----
 stackrc          | 6 ++++++
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/functions-common b/functions-common
index 24507fef91..83db9d3667 100644
--- a/functions-common
+++ b/functions-common
@@ -1165,7 +1165,7 @@ function uninstall_package {
     if is_ubuntu; then
         apt_get purge "$@"
     elif is_fedora; then
-        sudo yum remove -y "$@"
+        sudo $YUM remove -y "$@" ||:
     elif is_suse; then
         sudo zypper rm "$@"
     else
@@ -1174,7 +1174,7 @@ function uninstall_package {
 }
 
 # Wrapper for ``yum`` to set proxy environment variables
-# Uses globals ``OFFLINE``, ``*_proxy``
+# Uses globals ``OFFLINE``, ``*_proxy``, ``YUM``
 # yum_install package [package ...]
 function yum_install {
     [[ "$OFFLINE" = "True" ]] && return
@@ -1186,7 +1186,7 @@ function yum_install {
     # https://bugzilla.redhat.com/show_bug.cgi?id=965567
     $sudo http_proxy=$http_proxy https_proxy=$https_proxy \
         no_proxy=$no_proxy \
-        yum install -y "$@" 2>&1 | \
+        $YUM install -y "$@" 2>&1 | \
         awk '
             BEGIN { fail=0 }
             /No package/ { fail=1 }
@@ -1196,7 +1196,7 @@ function yum_install {
 
     # also ensure we catch a yum failure
     if [[ ${PIPESTATUS[0]} != 0 ]]; then
-        die $LINENO "Yum install failure"
+        die $LINENO "$YUM install failure"
     fi
 }
 
diff --git a/stackrc b/stackrc
index ac798894b8..2a5d877223 100644
--- a/stackrc
+++ b/stackrc
@@ -621,6 +621,12 @@ API_WORKERS=${API_WORKERS:=$(( ($(nproc)/2)<2 ? 2 : ($(nproc)/2) ))}
 # Service startup timeout
 SERVICE_TIMEOUT=${SERVICE_TIMEOUT:-60}
 
+# Support alternative yum -- in future Fedora 'dnf' will become the
+# only supported installer, but for now 'yum' and 'dnf' are both
+# available in parallel with compatible CLIs.  Allow manual switching
+# till we get to the point we need to handle this automatically
+YUM=${YUM:-yum}
+
 # Following entries need to be last items in file
 
 # Local variables: