add healthcheck, and stopsignal, plus export the correct port

Dockerfile

@@ -52,8 +52,10 @@ ENV RATELIMITS_NORMAL_TOTAL_REQUESTS=500\
     RATELIMITS_BLACKLIST=example1.blacklist,example2.blacklist 
 ENV DOCUMENTS=about=./about.md
 
-EXPOSE 7777
-
+EXPOSE ${PORT}
+STOPSIGNAL SIGINT
 ENTRYPOINT [ "bash", "docker-entrypoint.sh" ]
 
+HEALTHCHECK --interval=30s --timeout=30s --start-period=5s \
+    --retries=3 CMD [ "curl" , "-f" "localhost:${PORT}", "||", "exit", "1"]
 CMD ["npm", "start"]