frontend/Dockerfile — Added ARG + ENV for build-time variables

docker-compose.yml — Added build.args to pass the values into the Docker build:

docker-compose.yml

@@ -39,6 +39,10 @@ services:
     build:
       context: ./frontend
       dockerfile: Dockerfile
+      args:
+        NEXT_PUBLIC_API_URL: ${NEXT_PUBLIC_API_URL}
+        UPLOAD_R2_WORKER_API: ${UPLOAD_R2_WORKER_API}
+        R2_UPLOAD_API_KEY: ${R2_UPLOAD_API_KEY}
     restart: unless-stopped
     environment:
       NEXT_PUBLIC_API_URL: ${NEXT_PUBLIC_API_URL}

frontend/Dockerfile

@@ -3,6 +3,16 @@ WORKDIR /app
 COPY package*.json ./
 RUN npm ci
 COPY . .
+
+# Build args for NEXT_PUBLIC_ vars (baked in at build time)
+ARG NEXT_PUBLIC_API_URL
+ARG UPLOAD_R2_WORKER_API
+ARG R2_UPLOAD_API_KEY
+
+ENV NEXT_PUBLIC_API_URL=$NEXT_PUBLIC_API_URL
+ENV UPLOAD_R2_WORKER_API=$UPLOAD_R2_WORKER_API
+ENV R2_UPLOAD_API_KEY=$R2_UPLOAD_API_KEY
+
 RUN npm run build
 
 FROM node:20-alpine AS production