Fix BuildImage names

Add compatibility for Alpine Images.

root/etc/cont-init.d/97-apt-install

@@ -1,13 +0,0 @@
-#!/usr/bin/with-contenv bash
-
-# Exit if no installable packages are provided
-if [ -z ${APT_PACKAGES+x} ]; then
-    echo "**** No APT packages to install ****"
-    exit 0
-fi
-
-if [ -f /usr/bin/apt ]; then
-    apt install -y --no-install-recommends ${APT_PACKAGES}
-else
-    echo "!!! apt not found !!!"
-fi

root/etc/cont-init.d/97-install-packages

@@ -0,0 +1,17 @@
+#!/usr/bin/with-contenv bash
+
+# Exit if no installable packages are provided
+if [ -z ${INSTALL_PACKAGES+x} ]; then
+    echo "**** No packages to install ****"
+    exit 0
+fi
+
+# Ubuntu
+if [ -f /usr/bin/apt ]; then
+    apt install -y --no-install-recommends ${INSTALL_PACKAGES}
+fi
+
+# Alpine
+if [ -f /sbin/apk ]; then
+    apk add --no-cache ${INSTALL_PACKAGES}
+fi