Zero downtime deployment Nodejs application

Question

I have a Nodejs application that included clustering for being uptime and domain for error handling.

Now for achieving zero downtime deployment, I have an instruction but I need help to convert this instruction to Nodejs code (I need an example for it please).

This is the instruction:

1. When master starts, give it a symlink to worker code.
2. After deploying new code, update symlink
3. Send a signal to master: fork new workers!
4. Mater tells old workers to shut down, forks new workers from new code.
5. Mater process never stop running

Instruction source -> slide number 39

Answer 1

For 100% uptime the road is more or less the same regardless of the language you are using:

• Store your session tokens in a database rather than in an in-memory array or something. This will allow users to stay logged-in after you swap versions.

• Run your server inside a Docker container

• Use a proxy to handle swapping containers when you need to run a new server version.

I wrote easy-deploy to handle exactly that, so that I wouldn't need to worry about setting up the proxy every time.

Deploy version 1

easy-deploy -p 80:80 -v some/path:other/path my-image:1

To deploy a new version just run the command with the updated tag name

easy-deploy -p 80:80 -v some/path:other/path my-image:2

The proxy is taken care of. my-image:1 will be replaced by my-image:2 without letting any request drop.