cool cool - 1 year ago 72
Node.js Question

Node script - Failover from one server to another server

I have a nodejs script - lets call it "process1" on server1, and same script is running on server2 - "process2" (just with flag=false).

Process1 will be preforming actions and will be in "running" state at the beginning. process2 will be running but in "block" state with flag programmed within it.

What i want to acomplish is to, implement failover/fallback for this process. If process1 goes down flag on process2 will change, and process2 will take over all tasks from process1 (and vice versa when process1 cames back - fallback).

What is the best approach to do this? TCP connection between those?

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NOTE: Even its not too much relevant, but i want to mention that these processes are going to work internally, establishing tcp connection with third server and parsing data we are getting from that server. Both of the processes will be running on both of the servers, but only ONE process at the time can be providing services - running with flag true (and not both of them)

Update: As per discussions bellow and internal research/test and monitoring of solution, using reverse proxy will save you a lot of time. Programming fail-over based on 2 servers only will cover 70% of the cases related with the internal process which is used on the both machines - but you will not be able to detect others 30% of the issues caused because of the issues with the network (especially if you are having a lot of traffic towards DATA RECEIVER).

Answer Source

This is more of an infrastructure problem than it is a Node one, and the same situation can be applied to almost any server.

What you basically need is some service that monitors Server 1 and determines whether it's "healthy" or "alive" and if so continue to direct traffic to it. If the service determines that the server is no longer in a stable condition (e.g. it takes too long to respond, returns an error) it will redirect any incoming traffic to Server 2. When it's happy Server 1 has returned to normal operating conditions it will redirect the traffic back onto it.

In most cases, the "service" in this scenario is a reverse proxy like Nginx or CloudFlare. In your situation, this server would act as a buffer between Data Reciever and your network (Server 1 / Server 2) and route the incoming traffic to the relevant server.