Local dune libraries are not accessible within a mirage project

[kit-ty-kate]

Using mirage-skeleton's hello project as an example, adding a simple local dune library such as:

$ mkdir lib
$ echo "(library (name my_local_lib))" > lib/dune

then trying to declare it in mirage:

-let main = main ~packages:[ package "duration" ] "Unikernel.Hello" (time @-> job)
+let main = main ~packages:[ package "duration"; package "my_local_lib" ] "Unikernel.Hello" (time @-> job)

Will make opam-monorepo fail during make depends as my_local_lib is not an opam project available in opam-repository (and even if there was that would cause a conflict between the vendored duniverse/my_local_lib and my_local_lib)

Could there be an additional parameter to Mirage.package to declare the package as a local library?

[kit-ty-kate]

If anybody else is looking for a solution, the following hack works ok for me: https://github.com/kit-ty-kate/exn.st/blob/79bd396ef04ffbc22b8660d46286c7b39b54a13c/Dockerfile#L5

[hannesm]

As stated on IRC, I think the way to achieve this is to run mirage configure in the top-level with -f my_unikernel/config.ml, and thereafter dune build --root . my_unikernel/dist which will take the local lib into account.

That's at least from my memory/experience, you may want to take a look at https://github.com/mirage/mirage-crypto/blob/main/.test-mirage.sh (executed by .e.g .cirrus.yml) that attempts to compile these unikernels as a CI job with the HEAD of mirage-crypto...

[kit-ty-kate]

I think it isn’t great if the expected toolchain (mirage configure && make depends && mirage build) does not work and we have to go out of our way to make something that should have a simple solution, happen.

It would be nice to have an extra ?local_libs:string list argument to Mirage.main, to be able to do that out of the box.

[hannesm]

agreed, related to #1371