Made some Dockerfile changes

Dockerfile

@@ -59,13 +59,11 @@ RUN bundle exec bootsnap precompile -j 1 app/ lib/
 
 ENV ASSETS_PRECOMPILE=true
 
-ARG SECRET_KEY_BASE=dummy_key_for_asset_compilation
-ARG RAILS_MASTER_KEY=dummy_master_key
-
-ENV SECRET_KEY_BASE=${SECRET_KEY_BASE} \
-    RAILS_MASTER_KEY=${RAILS_MASTER_KEY}
-
-RUN ./bin/rails assets:precompile
+RUN --mount=type=secret,id=SECRET_KEY_BASE,mode=0444,required=true \
+    --mount=type=secret,id=RAILS_MASTER_KEY,mode=0444,required=true \
+    SECRET_KEY_BASE=$(cat /run/secrets/SECRET_KEY_BASE) \
+    RAILS_MASTER_KEY=$(cat /run/secrets/RAILS_MASTER_KEY) \
+    ./bin/rails assets:precompile
 
 # Final stage for app image
 FROM base