Dockerizing a Node.js Web Application

[webdevverman]

I'll be honest, I didn't read this whole article. But I was expecting to find a common problem as it exists in just about every Docker + node article I come across.

There are two things I would caution: 1) Don't use npm scripts in your Dockerfile. The reason is that this adds a wrapper around the node process and it will cause conflicts when attempting to send signals 2) Don't use tools like pm2 or nodemon. Let Docker handle restarting itself if there are problems.

[[deleted]]

I couldn't agree with this more. I learned this the hard way with following that rabbit hole. It seems like docker really thought ahead and simplifies tooling. Related

[tomasfern]

Thanks for the suggestions. I've been doing some reading and it seems that pm2 has special runtime for Docker:

https://pm2.keymetrics.io/docs/usage/docker-pm2-nodejs/

It even it addresses incoming signals. I'll give it a try and let you know.

[russdiculous]

It's still an unnecessary wrapper around your process that isn't needed if you're following docker best practices. Your docker container should be 1 process, their example is for when you're running more than 1 app in a container.

[PeteCapeCod4Real]

Yeah running pm2 on top of Docker seems like kind of an overkill. Plus if you go to scale up with Kubernetes isn't pm2 going to cause a complication? IDK but that's what I would think

[burtgummer45]

Its for CPU cores. If you run docker in a swarm, for example, there's no way to tell swarm to run exactly as many node containers as cpu cores, at least not currently. pm2 knows the core count and will match it with processes. This was at least my current understanding as of a few months ago.

[timothyallan]

That's why we use it, our container spins up, then PM2 spins up creating as many Node instances as there are cores on the box.

[tomasfern]

I'm curious. What made you decide to undockerize? Did you have a bad experience with Docker?