Fetch and pre-build dub dependencies

[Seb]

On Tuesday, 6 March 2018 at 18:03:34 UTC, Tamas wrote:
> I have a Dockerfile to build a vibe.d project. Docker has a 
> nice caching system so it continues building the docker image 
> from the step where it's needed when something changes. This is 
> typically at the step of adding my source files, then building 
> the binary.
>
> The problem is that fetching and building vibe dependencies 
> takes a lot of time every time some source files of mine 
> changes.
>
> I can pre-fetch dub dependencies, although it's a bit 
> cumbersome as fetch doesn't load dependencies of the given 
> package.
>
>     RUN dub fetch vibe-d --cache=system
>     RUN dub fetch vibe-core --cache=system
>     RUN dub fetch eventcore --cache=system
>     ....
>
> But there's no easy way to build these dependencies before I 
> add my project source files to the docker image. If I could do 
> that the docker build process would be tremendously faster, as 
> it would be simply skipped automatically by the Docker cache 
> system. Currently 99% of the time spent on building the 
> dependencies when i am creating a docker image. (I have to use 
> ldc for ARM, which is slower.)
>
> Is there an easy way to fetch and prebuild a dub package 
> dependencies?
>
> something like "dub fetch-and-build vibe-d --recursive 
> --cache=system"

For run.dlang.io, I fetch all dependencies and build them into 
the Docker image. That has the advantage that executions with dub 
packages are a lot faster.
It's just dub fetch and dub build though. Take a look:

https://github.com/dlang-tour/core-exec/blob/master/Dockerfile

dub fetch also fetches the dependencies of the package. The 
docker images don't have internet access on run.dlang.io, so it 
works fine for me. Maybe all you need is to disable the registry 
lookup?