Add unpack-installer.sh

Utility script for unpacking the installer, and downloading it if it
was missing.  It prefers the full installer over the over-the-internet
installer.

Signed-off-by: Chris Plock <chrisplo@cisco.com>

scripts/unpack-installer.sh

@@ -0,0 +1,40 @@
+#!/bin/bash
+
+# Will look for full installer, else the smaller installer, else download
+# the installer and unpack it.  Assumes "devbuild" unless BUILD_VERSION
+# is set
+# 'BUILD_VERSION=1.2.3 unpack-installer.sh' looks for:
+#  - contiv-full-1.2.3.tgz
+#  - contiv-1.2.3.tgz
+#  - https://github.com/contiv/install/releases/download/1.2.3/contiv-1.2.3.tgz
+
+set -euo pipefail
+
+cd "$(git rev-parse --show-toplevel)"
+mkdir -p release
+cd release
+
+#################################
+# Extract the installer
+#################################
+
+# If BUILD_VERSION is not defined, assume "devbuild" which presumably was
+# created with make BUILD_VERSION=devbuild
+BUILD_VERSION="${BUILD_VERSION:-devbuild}"
+release_name="contiv-${BUILD_VERSION}"
+
+rm -rf ${release_name}
+
+# this tarball has a cache of binary assets
+release_tarball="contiv-full-${BUILD_VERSION}.tgz"
+if [ ! -f "${release_tarball}" ]; then
+    release_tarball="${release_name}.tgz"
+fi
+if [ ! -f "${release_tarball}" ]; then
+    # For release builds, get the build from github releases
+    echo Downloading ${release_tarball} from GitHub releases
+    curl --fail -L -O https://github.com/contiv/install/releases/download/${BUILD_VERSION}/${release_tarball}
+fi
+
+echo Unpacking ${release_tarball}
+tar -zoxf "${release_tarball}"