Rust Docker custom dependencies - docker

Question

Im using cargo-wharf to build my Rust project.
Cargo.toml:
# syntax = denzp/cargo-wharf-frontend:v0.1.0-alpha.2
[package]
name = "project_name"
version = "0.1.0"
edition = "2018"
[dependencies]
dep1 = {path = "../dep1", version = "0.2.0"}
...
[package.metadata.wharf.builder]
image = "clux/muslrust:nightly-2019-09-28"
target = "x86_64-unknown-linux-musl"
[package.metadata.wharf.output]
image = "scratch"
user = "root"
entrypoint = ["/usr/local/bin/project_name"]
[[package.metadata.wharf.binary]]
name = "project_name"
destination = "/usr/local/bin/project_name"
When I run docker build -f Cargo.toml . -t project_name,
this error occurs:
[+] Building 5.2s (11/11) FINISHED
=> [internal] load build definition from Cargo.toml 0.0s
=> => transferring dockerfile: 1.38kB 0.0s
=> [internal] load .dockerignore 0.0s
=> => transferring context: 2B 0.0s
=> resolve image config for docker.io/denzp/cargo-wharf-frontend:v0.1.0-alpha.2 3.3s
=> CACHED docker-image://docker.io/denzp/cargo-wharf-frontend:v0.1.0-alpha.2#sha256:a57861317aa7ae8010927d6e000c9be523d3b78c2b42f3e5c281c8cc3328b1a0 0.0s
=> Using build context 0.0s
=> => transferring dockerfile: 6.41kB 0.0s
=> CACHED docker-image://docker.io/denzp/cargo-container-tools:v0.2.0-alpha.1 0.0s
=> => resolve docker.io/denzp/cargo-container-tools:v0.2.0-alpha.1 0.7s
=> CACHED Collecting configuration metadata 0.0s
=> Resolving builder image 0.5s
=> Using build context 0.0s
=> => transferring context: 6.41kB 0.0s
=> CACHED docker-image://docker.io/clux/muslrust:nightly-2019-09-28#sha256:05cd14b73ae42a978d67a12e099eac8f6fe61daf2a963b7f401817a246ba4948 0.0s
=> ERROR Evaluating the build plan 0.3s
------
> Evaluating the build plan:
#11 0.259 error: failed to load source for a dependency on `dep1`
#11 0.259
#11 0.259 Caused by:
#11 0.259 Unable to update /dep1
#11 0.259
#11 0.259 Caused by:
#11 0.259 failed to read `/dep1/Cargo.toml`
#11 0.259
#11 0.259 Caused by:
#11 0.259 No such file or directory (os error 2)
#11 0.259 error: Child process failed
------
failed to solve with frontend dockerfile.v0: failed to solve with frontend gateway.v0: rpc error: code = Unknown desc = Unable to evaluate the Cargo build plan => caused by: Unable to read Cargo build plan => caused by: Unable to read the file => caused by: grpc-status: Unknown, grpc-message: "executor failed running [/usr/local/bin/cargo-build-plan --manifest-path /context/Cargo.toml --output /output/build-plan.json --target x86_64-unknown-linux-musl --release]: exit code: 1"
dep1 is a custom package that is at the same level as project_name.
So it is C:\Users\me\shared_folder\project_name\Cargo.toml
and C:\Users\me\shared_folder\dep1\Cargo.toml
When running cargo run from C:\Users\me\shared_folder\project_name\Cargo.toml, everything just works fine.
I already tried:
changing edition = "2018" as I read somewhere had no impact
deleted Cargo.lock and target folder, also didn't work for me
Does anyone know how to get my program + custom dependencies running in docker?

Answer 1

I'm somewhat baffled that this is possible, but the solution to your problem is easy:
You'll need to include the entire shared_folder (which contains both lib1 and project_name) as build context, i.e. your build context must be .. not .. Otherwise, the dockerized builder has no way of accessing lib1.
You'll need to specify where to find your Cargo.toml since it's not in the working directory of the builder anymore. You could do that by adding a workspace Cargo.toml to shared_folder, but I think that using --build-arg manifest-path=… is easier.
In summary:
buildx build -f Cargo.toml --build-arg manifest-path=project_name/Cargo.toml ..