use pm2 to guard and monitor the web service in docker file (#2238)

web/Dockerfile

@@ -40,12 +40,17 @@ ENV TZ UTC
 RUN ln -s /usr/share/zoneinfo/${TZ} /etc/localtime \
     && echo ${TZ} > /etc/timezone
 
+# global runtime packages
+RUN yarn global add pm2 \
+    && yarn cache clean
+
 WORKDIR /app/web
 COPY --from=builder /app/web/public ./public
 COPY --from=builder /app/web/.next/standalone ./
 COPY --from=builder /app/web/.next/static ./.next/static
 
 
+COPY docker/pm2.json ./pm2.json
 COPY docker/entrypoint.sh ./entrypoint.sh
 
 ARG COMMIT_SHA