diff --git a/functions b/functions
index 6f2164a777..ebcae334e0 100644
--- a/functions
+++ b/functions
@@ -45,6 +45,37 @@ function short_source {
 # export it so child shells have access to the 'short_source' function also.
 export -f short_source
 
+# Download a file from a URL
+#
+# Will check cache (in $FILES) or download given URL.
+#
+# Argument is the URL to the remote file
+#
+# Will echo the local path to the file as the output.  Will die on
+# failure to download.
+#
+# Files can be pre-cached for CI environments, see EXTRA_CACHE_URLS
+# and tools/image_list.sh
+function get_extra_file {
+    local file_url=$1
+
+    file_name=$(basename "$file_url")
+    if [[ $file_url != file* ]]; then
+        # If the file isn't cache, download it
+        if [[ ! -f $FILES/$file_name ]]; then
+            wget --progress=dot:giga -c $file_url -O $FILES/$file_name
+            if [[ $? -ne 0 ]]; then
+                die "$file_url could not be downloaded"
+            fi
+        fi
+        echo "$FILES/$file_name"
+        return
+    else
+        # just strip the file:// bit and that's the path to the file
+        echo $file_url | sed 's/$file:\/\///g'
+    fi
+}
+
 
 # Retrieve an image from a URL and upload into Glance.
 # Uses the following variables:
diff --git a/lib/etcd3 b/lib/etcd3
index 6e32cb31ca..60e827add2 100644
--- a/lib/etcd3
+++ b/lib/etcd3
@@ -24,15 +24,9 @@ set +o xtrace
 # --------
 
 # Set up default values for etcd
-ETCD_DOWNLOAD_URL=${ETCD_DOWNLOAD_URL:-https://github.com/coreos/etcd/releases/download}
-ETCD_VERSION=${ETCD_VERSION:-v3.1.7}
 ETCD_DATA_DIR="$DATA_DIR/etcd"
 ETCD_SYSTEMD_SERVICE="devstack@etcd.service"
 ETCD_BIN_DIR="$DEST/bin"
-ETCD_SHA256_AMD64="4fde194bbcd259401e2b5c462dfa579ee7f6af539f13f130b8f5b4f52e3b3c52"
-# NOTE(sdague): etcd v3.1.7 doesn't have anything for these architectures, though 3.2.0 does.
-ETCD_SHA256_ARM64=""
-ETCD_SHA256_PPC64=""
 ETCD_PORT=2379
 
 if is_ubuntu ; then
@@ -95,37 +89,19 @@ function cleanup_etcd3 {
 function install_etcd3 {
     echo "Installing etcd"
 
-    # Make sure etcd3 downloads the correct architecture
-    if is_arch "x86_64"; then
-        ETCD_ARCH="amd64"
-        ETCD_SHA256=${ETCD_SHA256:-$ETCD_SHA256_AMD64}
-    elif is_arch "aarch64"; then
-        ETCD_ARCH="arm64"
-        ETCD_SHA256=${ETCD_SHA256:-$ETCD_SHA256_ARM64}
-    elif is_arch "ppc64le"; then
-        ETCD_ARCH="ppc64le"
-        ETCD_SHA256=${ETCD_SHA256:-$ETCD_SHA256_PPC64}
-    else
-        exit_distro_not_supported "invalid hardware type - $ETCD_ARCH"
-    fi
-
-    ETCD_NAME=etcd-$ETCD_VERSION-linux-$ETCD_ARCH
-
     # Create the necessary directories
     sudo mkdir -p $ETCD_BIN_DIR
     sudo mkdir -p $ETCD_DATA_DIR
 
     # Download and cache the etcd tgz for subsequent use
+    local etcd_file
+    etcd_file="$(get_extra_file $ETCD_DOWNLOAD_LOCATION)"
     if [ ! -f "$FILES/etcd-$ETCD_VERSION-linux-$ETCD_ARCH/etcd" ]; then
-        ETCD_DOWNLOAD_FILE=$ETCD_NAME.tar.gz
-        if [ ! -f "$FILES/$ETCD_DOWNLOAD_FILE" ]; then
-            wget $ETCD_DOWNLOAD_URL/$ETCD_VERSION/$ETCD_DOWNLOAD_FILE -O $FILES/$ETCD_DOWNLOAD_FILE
-        fi
-        echo "${ETCD_SHA256} $FILES/${ETCD_DOWNLOAD_FILE}" > $FILES/etcd.sha256sum
+        echo "${ETCD_SHA256} $etcd_file" > $FILES/etcd.sha256sum
         # NOTE(sdague): this should go fatal if this fails
         sha256sum -c $FILES/etcd.sha256sum
 
-        tar xzvf $FILES/$ETCD_DOWNLOAD_FILE -C $FILES
+        tar xzvf $etcd_file -C $FILES
         sudo cp $FILES/$ETCD_NAME/etcd $ETCD_BIN_DIR/etcd
     fi
     if [ ! -f "$ETCD_BIN_DIR/etcd" ]; then
diff --git a/stackrc b/stackrc
index b123d8ac7c..0757d78775 100644
--- a/stackrc
+++ b/stackrc
@@ -732,6 +732,40 @@ if [[ "$DOWNLOAD_DEFAULT_IMAGES" == "True" ]]; then
     DOWNLOAD_DEFAULT_IMAGES=False
 fi
 
+# This is a comma separated list of extra URLS to be listed for
+# download by the tools/image_list.sh script.  CI environments can
+# pre-download these URLS and place them in $FILES.  Later scripts can
+# then use "get_extra_file <url>" which will print out the path to the
+# file; it will either be downloaded on demand or acquired from the
+# cache if there.
+EXTRA_CACHE_URLS=""
+
+# etcd3 defaults
+ETCD_VERSION=${ETCD_VERSION:-v3.1.7}
+ETCD_SHA256_AMD64="4fde194bbcd259401e2b5c462dfa579ee7f6af539f13f130b8f5b4f52e3b3c52"
+# NOTE(sdague): etcd v3.1.7 doesn't have anything for these architectures, though 3.2.0 does.
+ETCD_SHA256_ARM64=""
+ETCD_SHA256_PPC64=""
+# Make sure etcd3 downloads the correct architecture
+if is_arch "x86_64"; then
+    ETCD_ARCH="amd64"
+    ETCD_SHA256=${ETCD_SHA256:-$ETCD_SHA256_AMD64}
+elif is_arch "aarch64"; then
+    ETCD_ARCH="arm64"
+    ETCD_SHA256=${ETCD_SHA256:-$ETCD_SHA256_ARM64}
+elif is_arch "ppc64le"; then
+    ETCD_ARCH="ppc64le"
+    ETCD_SHA256=${ETCD_SHA256:-$ETCD_SHA256_PPC64}
+else
+    exit_distro_not_supported "invalid hardware type - $ETCD_ARCH"
+fi
+ETCD_DOWNLOAD_URL=${ETCD_DOWNLOAD_URL:-https://github.com/coreos/etcd/releases/download}
+ETCD_NAME=etcd-$ETCD_VERSION-linux-$ETCD_ARCH
+ETCD_DOWNLOAD_FILE=$ETCD_NAME.tar.gz
+ETCD_DOWNLOAD_LOCATION=$ETCD_DOWNLOAD_URL/$ETCD_VERSION/$ETCD_DOWNLOAD_FILE
+# etcd is always required, so place it into list of pre-cached downloads
+EXTRA_CACHE_URLS+=",$ETCD_DOWNLOAD_LOCATION"
+
 # 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
diff --git a/tools/image_list.sh b/tools/image_list.sh
index 29b93ed1d8..3a27c4acfd 100755
--- a/tools/image_list.sh
+++ b/tools/image_list.sh
@@ -1,5 +1,14 @@
 #!/bin/bash
 
+# Print out a list of image and other files to download for caching.
+# This is mostly used by the OpenStack infrasturucture during daily
+# image builds to save the large images to /opt/cache/files (see [1])
+#
+# The two lists of URL's downloaded are the IMAGE_URLS and
+# EXTRA_CACHE_URLS, which are setup in stackrc
+#
+# [1] project-config:nodepool/elements/cache-devstack/extra-data.d/55-cache-devstack-repos
+
 # Keep track of the DevStack directory
 TOP_DIR=$(cd $(dirname "$0")/.. && pwd)
 
@@ -31,12 +40,20 @@ for driver in $DRIVERS; do
     ALL_IMAGES+=$URLS
 done
 
-# Make a nice list
-echo $ALL_IMAGES | tr ',' '\n' | sort | uniq
-
 # Sanity check - ensure we have a minimum number of images
 num=$(echo $ALL_IMAGES | tr ',' '\n' | sort | uniq | wc -l)
 if [[ "$num" -lt 4 ]]; then
     echo "ERROR: We only found $num images in $ALL_IMAGES, which can't be right."
     exit 1
 fi
+
+# This is extra non-image files that we want pre-cached.  This is kept
+# in a separate list because devstack loops over the IMAGE_LIST to
+# upload files glance and these aren't images.  (This was a bit of an
+# after-thought which is why the naming around this is very
+# image-centric)
+URLS=$(source $TOP_DIR/stackrc && echo $EXTRA_CACHE_URLS)
+ALL_IMAGES+=$URLS
+
+# Make a nice combined list
+echo $ALL_IMAGES | tr ',' '\n' | sort | uniq