Update Dockerfile

Dockerfile

@@ -1,8 +1,5 @@
 FROM node:16-alpine as build-frontend
 
-RUN --mount=type=secret,id=PUBLIC_BACKEND_WS_URL,mode=0444,required=true \
- export PUBLIC_BACKEND_WS_URL=$(cat /run/secrets/PUBLIC_BACKEND_WS_URL)
- 
 # Set the working directory
 WORKDIR /app
 
@@ -14,6 +11,9 @@ RUN npm ci --prefix frontend/
 # Copy the rest of the application files
 COPY frontend/ /app/frontend/
 
+RUN --mount=type=secret,id=PUBLIC_BACKEND_WS_URL,mode=0444,required=true \
+  echo "A=$(cat /run/secrets/PUBLIC_BACKEND_WS_URL)" > frontend/.env
+ 
 RUN npm run build --prefix frontend/
 
 # Start a new stage using python:3.9-alpine