alt Hacker NewsSomewhat adjacent in how I look at using Docker at all in prod, here's what I always wonder:
Is using Docker/Compose "just" as the layer for installing & managing runtime environment and services correct? Especially for languages like PHP?
I.e. am I holding it wrong if I run my "build" processes (npm, composer, etc) on the server at deploy time same as I would without containers? In that sense Docker Composer becomes more like Ansible for me - the tool I use to build the environment, not the entire app.
For the purpose of my question, let's assume I'm building normal CRUD services that can go a little tall or a little wide on servers without caring about hyper scale.
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I would say it's bad practice because you end up having to copy all the build dependencies (source code) to the host and you're potentially putting a bunch of extra load on the host during the build process.
Also adds moving parts to your deploy which increases risk/introduces more failure modes.
Couple things that come to mind
- disk space exhaustion during build
- I/o exhaustion esp with package managers that have lots of small files (npm)
However, on the small/hobby end I don't think it's a huge concern.
Have a look at multi stage container builds. Your images should not need a build step at start, the result should be in the baked image. Else you become reliant on fetching packages during build etc.
> if I run my "build" processes (npm, composer, etc) on the server at deploy time
It's perfectly fine, as long as you accept the risks and downsides. Your IP can get ratelimited for Docker Hub. The build process can exhaust resources on the host. Your server probably needs access to internal dev dependencies repository, thus, needs credentials it would not need otherwise. Many small things like that. The advantage is simplicity, and it's often worth the risk.