WIP: feat: simple alpine Dockerfile #151

Add a simple alpine dockerfile using cargo-chef to build
silverfish-stall images.

The image comes out at 32.5 MiB. This is not thought as a "production"
image, but just as a base image from which to build a production image.

I would like this to be pushed as a package as part of the release, in addition to the release binaries.

We could then have a silverfish-contrib folder or repo with a fly.dockerfile that consumes this image and is ready to use with fly.io or similar providers.

I generally don't like having significantly different build toolchains for deploy as compared to the build toolchain for test. could you explain a bit what we gain here by using cargo chef instead of just running a normal build?

@cjdesno wrote in #151 (comment):

I generally don't like having significantly different build toolchains for deploy as compared to the build toolchain for test. could you explain a bit what we gain here by using cargo chef instead of just running a normal build?

If you have docker caching setup, then cargo-chef lets you cache the layers more effectively, basically, cargo chef cook only runs if the dependencies change.

Then again, this isn't necessary, so we could just remove it and do a clean build every time.

i see, yeah i'd rather we just do a clean build here then.

if we want to push this image as part of the release, i wonder if it would make more sense to just build for musl in the release job (WIP: #161 ) and then pull the binary into this image, vs building both here and there. i'm open to either approach, haven't looked into what's standard for this.