Make use of Ubuntu Cloud Archive switchable

The trove development environment is typically a linux VM within which
openstack is installed, and trove launches guest vm's within that
environment. To make it possible for these vm's to launch in one human
lifetime, one must set vt/x and enable nested hypervisors to use with
kvm; qemu emulation will take way too long.

The new libvirtd (v2.5.0) in Ubuntu Cloud Archive doesn't handle
nested hypervisors well and if you use it, you end up with a guest
hanging on the GRUB line.

To enable that use-case, we provide ENABLE_UBUNTU_CLOUD_ARCHIVE which
the trove developer can set (to False) before running devstack.

Change-Id: Ia0265c67bb7d2a438575a03c0ddbf2d9c53266ed
Closes-Bug: #1689370

Author: amrith

stackrc

@@ -665,6 +665,8 @@ case "$VIRT_DRIVER" in
         ;;
 esac
 
+# By default, devstack will use Ubuntu Cloud Archive.
+ENABLE_UBUNTU_CLOUD_ARCHIVE=$(trueorfalse True ENABLE_UBUNTU_CLOUD_ARCHIVE)
 
 # Images
 # ------

tools/fixup_stuff.sh

@@ -72,7 +72,10 @@ fi
 # We've found that Libvirt on Xenial is flaky and crashes enough to be
 # a regular top e-r bug. Opt into Ubuntu Cloud Archive if on Xenial to
 # get newer Libvirt.
-if [[ "$DISTRO" = "xenial" ]]; then
+# Make it possible to switch this based on an environment variable as
+# libvirt 2.5.0 doesn't handle nested virtualization quite well and this
+# is required for the trove development environment.
+if [[ "${ENABLE_UBUNTU_CLOUD_ARCHIVE}" == "True" && "$DISTRO" = "xenial" ]]; then
     # This pulls in apt-add-repository
     install_package "software-properties-common"
     # Use UCA for newer libvirt. Should give us libvirt 2.5.0.