diff --git a/doc/source/configuration.rst b/doc/source/configuration.rst
index 90b7d44dec..fef395c327 100644
--- a/doc/source/configuration.rst
+++ b/doc/source/configuration.rst
@@ -396,6 +396,24 @@ Set the following options to point to the master
         GLANCE_HOSTPORT=w.x.y.z:9292
         ENABLED_SERVICES=n-vol,n-cpu,n-net,n-api
 
+Guest Images
+------------
+
+Images provided in URLS via the comma-separated ``IMAGE_URLS``
+variable will be downloaded and uploaded to glance by DevStack.
+
+Default guest-images are predefined for each type of hypervisor and
+their testing-requirements in ``stack.sh``.  Setting
+``DOWNLOAD_DEFAULT_IMAGES=False`` will prevent DevStack downloading
+these default images; in that case, you will want to populate
+``IMAGE_URLS`` with sufficient images to satisfy testing-requirements.
+
+    ::
+
+        DOWNLOAD_DEFAULT_IMAGES=False
+        IMAGE_URLS="http://foo.bar.com/image.qcow,"
+        IMAGE_URLS+="http://foo.bar.com/image2.qcow"
+
 IP Version
 ----------
 
diff --git a/stackrc b/stackrc
index 156cb1f85a..43292a5e02 100644
--- a/stackrc
+++ b/stackrc
@@ -2,6 +2,11 @@
 #
 # stackrc
 #
+
+# ensure we don't re-source this in the same environment
+[[ -z "$_DEVSTACK_STACKRC" ]] || return 0
+declare -r _DEVSTACK_STACKRC=1
+
 # Find the other rc files
 RC_DIR=$(cd $(dirname "${BASH_SOURCE:-$0}") && pwd)
 
@@ -560,40 +565,47 @@ CIRROS_ARCH=${CIRROS_ARCH:-"x86_64"}
 # Set default image based on ``VIRT_DRIVER`` and ``LIBVIRT_TYPE``, either of
 # which may be set in ``local.conf``.  Also allow ``DEFAULT_IMAGE_NAME`` and
 # ``IMAGE_URLS`` to be set in the `localrc` section of ``local.conf``.
-case "$VIRT_DRIVER" in
-    openvz)
-        DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-ubuntu-12.04-x86_64}
-        IMAGE_URLS=${IMAGE_URLS:-"http://download.openvz.org/template/precreated/ubuntu-12.04-x86_64.tar.gz"};;
-    libvirt)
-        case "$LIBVIRT_TYPE" in
-            lxc) # the cirros root disk in the uec tarball is empty, so it will not work for lxc
-                DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-${CIRROS_VERSION}-${CIRROS_ARCH}-rootfs}
-                IMAGE_URLS=${IMAGE_URLS:-"http://download.cirros-cloud.net/${CIRROS_VERSION}/cirros-${CIRROS_VERSION}-${CIRROS_ARCH}-rootfs.img.gz"};;
-            *) # otherwise, use the uec style image (with kernel, ramdisk, disk)
-                DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-${CIRROS_VERSION}-${CIRROS_ARCH}-uec}
-                IMAGE_URLS=${IMAGE_URLS:-"http://download.cirros-cloud.net/${CIRROS_VERSION}/cirros-${CIRROS_VERSION}-${CIRROS_ARCH}-uec.tar.gz"};;
-        esac
-        ;;
-    vsphere)
-        DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-0.3.2-i386-disk.vmdk}
-        IMAGE_URLS=${IMAGE_URLS:-"http://partnerweb.vmware.com/programs/vmdkimage/cirros-0.3.2-i386-disk.vmdk"};;
-    xenserver)
-        DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-0.3.4-x86_64-disk}
-        IMAGE_URLS=${IMAGE_URLS:-"http://ca.downloads.xensource.com/OpenStack/cirros-0.3.4-x86_64-disk.vhd.tgz"}
-        IMAGE_URLS+=",http://download.cirros-cloud.net/${CIRROS_VERSION}/cirros-${CIRROS_VERSION}-x86_64-uec.tar.gz";;
-    ironic)
-        # Ironic can do both partition and full disk images, depending on the driver
-        if [[ "$IRONIC_DEPLOY_DRIVER" == "agent_ssh" ]]; then
-            DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-${CIRROS_VERSION}-x86_64-disk}
-        else
-            DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-${CIRROS_VERSION}-x86_64-uec}
-        fi
-        IMAGE_URLS=${IMAGE_URLS:-"http://download.cirros-cloud.net/${CIRROS_VERSION}/cirros-${CIRROS_VERSION}-x86_64-uec.tar.gz"}
-        IMAGE_URLS+=",http://download.cirros-cloud.net/${CIRROS_VERSION}/cirros-${CIRROS_VERSION}-x86_64-disk.img";;
-    *) # Default to Cirros with kernel, ramdisk and disk image
-        DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-${CIRROS_VERSION}-${CIRROS_ARCH}-uec}
-        IMAGE_URLS=${IMAGE_URLS:-"http://download.cirros-cloud.net/${CIRROS_VERSION}/cirros-${CIRROS_VERSION}-${CIRROS_ARCH}-uec.tar.gz"};;
-esac
+DOWNLOAD_DEFAULT_IMAGES=$(trueorfalse True DOWNLOAD_DEFAULT_IMAGES)
+if [[ "$DOWNLOAD_DEFAULT_IMAGES" == "True" ]]; then
+    if [ -n $IMAGE_URLS ]; then
+        IMAGE_URLS+=","
+    fi
+    case "$VIRT_DRIVER" in
+        openvz)
+            DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-ubuntu-12.04-x86_64}
+            IMAGE_URLS+="http://download.openvz.org/template/precreated/ubuntu-12.04-x86_64.tar.gz";;
+        libvirt)
+            case "$LIBVIRT_TYPE" in
+                lxc) # the cirros root disk in the uec tarball is empty, so it will not work for lxc
+                    DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-${CIRROS_VERSION}-${CIRROS_ARCH}-rootfs}
+                    IMAGE_URLS+="http://download.cirros-cloud.net/${CIRROS_VERSION}/cirros-${CIRROS_VERSION}-${CIRROS_ARCH}-rootfs.img.gz";;
+                *) # otherwise, use the uec style image (with kernel, ramdisk, disk)
+                    DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-${CIRROS_VERSION}-${CIRROS_ARCH}-uec}
+                    IMAGE_URLS+="http://download.cirros-cloud.net/${CIRROS_VERSION}/cirros-${CIRROS_VERSION}-${CIRROS_ARCH}-uec.tar.gz";;
+                esac
+            ;;
+        vsphere)
+            DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-0.3.2-i386-disk.vmdk}
+            IMAGE_URLS+="http://partnerweb.vmware.com/programs/vmdkimage/cirros-0.3.2-i386-disk.vmdk";;
+        xenserver)
+            DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-0.3.4-x86_64-disk}
+            IMAGE_URLS+="http://ca.downloads.xensource.com/OpenStack/cirros-0.3.4-x86_64-disk.vhd.tgz"
+            IMAGE_URLS+=",http://download.cirros-cloud.net/${CIRROS_VERSION}/cirros-${CIRROS_VERSION}-x86_64-uec.tar.gz";;
+        ironic)
+            # Ironic can do both partition and full disk images, depending on the driver
+            if [[ "$IRONIC_DEPLOY_DRIVER" == "agent_ssh" ]]; then
+                DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-${CIRROS_VERSION}-x86_64-disk}
+            else
+                DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-${CIRROS_VERSION}-x86_64-uec}
+            fi
+            IMAGE_URLS+="http://download.cirros-cloud.net/${CIRROS_VERSION}/cirros-${CIRROS_VERSION}-x86_64-uec.tar.gz"
+            IMAGE_URLS+=",http://download.cirros-cloud.net/${CIRROS_VERSION}/cirros-${CIRROS_VERSION}-x86_64-disk.img";;
+        *) # Default to Cirros with kernel, ramdisk and disk image
+            DEFAULT_IMAGE_NAME=${DEFAULT_IMAGE_NAME:-cirros-${CIRROS_VERSION}-${CIRROS_ARCH}-uec}
+            IMAGE_URLS+="http://download.cirros-cloud.net/${CIRROS_VERSION}/cirros-${CIRROS_VERSION}-${CIRROS_ARCH}-uec.tar.gz";;
+    esac
+    DOWNLOAD_DEFAULT_IMAGES=False
+fi
 
 # Staging Area for New Images, have them here for at least 24hrs for nodepool
 # to cache them otherwise the failure rates in the gate are too high
@@ -606,6 +618,13 @@ if [[ "$PRECACHE_IMAGES" == "True" ]]; then
     fi
 fi
 
+# Detect duplicate values in IMAGE_URLS
+for image_url in ${IMAGE_URLS//,/ }; do
+    if [ $(echo "$IMAGE_URLS" | grep -o -F "$image_url" | wc -l) -gt 1 ]; then
+        die $LINENO "$image_url is duplicate, please remove it from IMAGE_URLS."
+    fi
+done
+
 # 10Gb default volume backing file size
 VOLUME_BACKING_FILE_SIZE=${VOLUME_BACKING_FILE_SIZE:-10250M}
 
diff --git a/tools/xen/README.md b/tools/xen/README.md
index 61694e9616..6212cc54d7 100644
--- a/tools/xen/README.md
+++ b/tools/xen/README.md
@@ -94,11 +94,6 @@ Of course, use real passwords if this machine is exposed.
     XENAPI_CONNECTION_URL="http://address_of_your_xenserver"
     VNCSERVER_PROXYCLIENT_ADDRESS=address_of_your_xenserver
 
-    # Download a vhd and a uec image
-    IMAGE_URLS="\
-    https://github.com/downloads/citrix-openstack/warehouse/cirros-0.3.0-x86_64-disk.vhd.tgz,\
-    http://download.cirros-cloud.net/0.3.4/cirros-0.3.4-x86_64-uec.tar.gz"
-
     # Explicitly set virt driver
     VIRT_DRIVER=xenserver