Using Docker with nodejs with node-gyp dependencies
I'm planning to use Docker to deploy a node.js app. The app has several dependencies that require node-gyp. Node-gyp builds these modules (e.g. canvas, lwip, qrcode) against compiled libraries on the delivery platform, and in my experience these builds can be highly dependent on the o/s version and libraries installed, and they often break a simple npm install.
So is building my Dockerfile FROM node:version the correct approach? This seems to be the approach shown in every Docker/Node tutorial I've found so far. But if I build from a node image, what will happen when I deploy the container? How can I ensure the target host will have the libraries needed to compile the node-gyp modules?
The other way I'm looking at is to build the Dockerfile FROM ubuntu:version. But I think this would mean installing nodeJS into the Ubuntu image and the whole thing would be much larger.
Are there other ways of handling this?
Answer
How can I ensure the target host will have the libraries needed to compile the node-gyp modules?
The target host is running docker as well. As long as the dependencies are in your image then your server has them as well. That's the entire point with docker if you ask me. If it runs locally, then it runs on the server as well.
I'd go with node-alpine (FROM node:8-alpine) for even smaller files. I struggled with node-gyp before I wrapped my head around it, but now I don't even see how I ever thought it was a problem. As long as you add build tools RUN apk add python make gcc g++ you are good to go (this adds some 100-200mb to the size however).
Also if it ever gets time consuming (say you find yourself rebuilding your image with --no-cache every now and then) then it can be a good idea to split it up into a base-image of your own and another image FROM my-base-image:latest which contains things that you change a more often.
There is some learning curve for sure, but I didn't find it that steep. At least not if you have touched docker before.
The other way I'm looking at is to build the Dockerfile FROM ubuntu:version.
I had only used CentOS before jumping on docker, and I run CentOS on my servers. So I thought it would be a good idea to run CentOS-images as well, but I found that to be just silly. There is absolutely zero gain unless you need something very OS-specific. Now I've only used alpine for maybe half a year, and so far the only alpine-specific command I've needed to learn is apk add/del.
And you probably know already, but don't spend too much time optimizing docker file size in the beginning. (You can reduce layer size a lot by combining commands on one line, (adding packages, running command, removing packages). But that cancels out the use of the docker image cache if you make any small changes in big layers. Better to leave that out until it matters.