cleaning up environment variable configuration

.env.production

-API_PREFIX=/api
+API_BASE=backend
 API_PORT=8080
+API_PREFIX=/api
 FRONTEND_PORT=8090
 VITE_FRONTEND_PORT=$FRONTEND_PORT
 VITE_API_PREFIX=$API_PREFIX

Dockerfile

@@ -10,14 +10,16 @@ RUN npm run build -- --mode production
 FROM nginx:stable-alpine AS production-stage
 ARG FRONTEND_PORT=8090
 ARG API_PORT=8080
+ARG API_BASE=backend
 ARG API_PREFIX=/api
 ENV FRONTEND_PORT=$FRONTEND_PORT
+ENV API_BASE=$API_BASE
 ENV API_PORT=$API_PORT
 ENV API_PREFIX=$API_PREFIX
 
 COPY --from=build-stage /app/dist /usr/share/nginx/html
 COPY nginx.conf.template /etc/nginx/conf.d/default.conf.template
-RUN envsubst '\$API_PORT \$FRONTEND_PORT \$API_PREFIX' < /etc/nginx/conf.d/default.conf.template > /etc/nginx/conf.d/default.conf
+RUN envsubst '\$API_BASE \$API_PORT \$FRONTEND_PORT \$API_PREFIX' < /etc/nginx/conf.d/default.conf.template > /etc/nginx/conf.d/default.conf
 RUN cat /etc/nginx/conf.d/default.conf
 EXPOSE $FRONTEND_PORT
 CMD ["nginx", "-g", "daemon off;"]
\ No newline at end of file

nginx.conf.template

 upstream api {
-    server backend:${API_PORT};
+    server ${API_BASE}:${API_PORT};
 }
 
 server {