adds build_args_from_env option

plugin.sh

@@ -47,13 +47,9 @@ if [ -n "${PLUGIN_BUILD_ARGS:-}" ]; then
 fi
 
 if [ -n "${PLUGIN_BUILD_ARGS_FROM_ENV:-}" ]; then
-    BUILD_ARGS_FROM_ENV=$(echo "${PLUGIN_BUILD_ARGS_FROM_ENV}" | tr ',' '\n' | while read build_arg; do echo "--build-arg=${build_arg}=${!build_arg}"; done)
+    BUILD_ARGS_FROM_ENV=$(echo "${PLUGIN_BUILD_ARGS_FROM_ENV}" | tr ',' '\n' | while read build_arg; do echo "--build-arg ${build_arg}=$(eval "echo \$$build_arg")"; done)
 fi
 
-echo "BUILD_ARGS_FROM_ENV"
-echo ${BUILD_ARGS_FROM_ENV:-}
-echo "BUILD_ARGS_FROM_ENV END"
-
 if [ -n "${PLUGIN_TAGS:-}" ]; then
     DESTINATIONS=$(echo "${PLUGIN_TAGS}" | tr ',' '\n' | while read tag; do echo "--destination=${REGISTRY}/${PLUGIN_REPO}:${tag} "; done)
 elif [ -f .tags ]; then
@@ -73,4 +69,5 @@ fi
     ${DESTINATIONS} \
     ${CACHE:-} \
     ${TARGET:-} \
-    ${BUILD_ARGS:-}
+    ${BUILD_ARGS:-} \
+    ${BUILD_ARGS_FROM_ENV:-}