Recommended recipe for deploying a Julia app in Docker with efficient precompilation?

[ffevotte]

@robsmith11

Is there a recommended way to build Julia docker images that will

1. Do all precompilation during image creation rather than when a image is run,

Simply running Pkg.instantiate in your project should do the trick. I.e something like

COPY .... # copy the sources from your project into the Docker image
RUN julia --project="/path/to/my/project" \
          -e "import Pkg; Pkg.instantiate()"

@robsmith11

2. Cache as much dependency precompilation as possible, so that rebuilding a docker image only needs to update the precompilation for my app’s own code?

I’m less sure about this one. Perhaps you could copy the Project.toml file from your project (and perhaps also the Manifest.toml if you version it) to a temporary directory in the Docker image in an earlier stage, and Pkg.instantiate it at that time. This way, Docker should cache the results from this stage (including all precompiled packages) and when you later instantiate your real project, Julia/Pkg should find most of the dependencies already precompiled (provided their versions didn’t change inbetween).