fix: Update Docker entrypoint script to set default PORT and modify nginx configuration

Author: ChingEnLin

frontend/Dockerfile

@@ -24,7 +24,9 @@ COPY nginx.conf /etc/nginx/conf.d/default.conf.template
 
 # Create script to substitute environment variables in nginx config
 RUN echo '#!/bin/sh' > /docker-entrypoint.sh && \
-    echo 'envsubst < /etc/nginx/conf.d/default.conf.template > /etc/nginx/conf.d/default.conf' >> /docker-entrypoint.sh && \
+    echo '# Set PORT default if not provided' >> /docker-entrypoint.sh && \
+    echo 'export PORT=${PORT:-4000}' >> /docker-entrypoint.sh && \
+    echo 'envsubst "\$PORT" < /etc/nginx/conf.d/default.conf.template > /etc/nginx/conf.d/default.conf' >> /docker-entrypoint.sh && \
     echo 'exec nginx -g "daemon off;"' >> /docker-entrypoint.sh && \
     chmod +x /docker-entrypoint.sh
 

frontend/nginx.conf

@@ -1,5 +1,5 @@
 server {
-    listen       ${PORT:-4000};
+    listen       $PORT;
     server_name  localhost;
 
     location / {