document how to run cross

[glehmann]

I've seen cross mentioned in the documentation, so I thought it could be easy to run it. Not that much so far :-)

Here is what I tried to do:

VERSION --global-cache 0.7
IMPORT github.com/earthly/lib/rust AS rust

rust:
    FROM rust:alpine
    RUN apk add --no-cache musl-dev findutils
    DO rust+INIT --keep_fingerprints=true

cross:
    FROM +rust
    DO rust+CARGO --args="install cross"
    RUN apk add docker jq
    ARG --required target
    DO rust+SET_CACHE_MOUNTS_ENV
    COPY --keep-ts . ./
    WITH DOCKER
        RUN --mount=$EARTHLY_RUST_CARGO_HOME_CACHE \
            --mount=$EARTHLY_RUST_TARGET_CACHE \
            cross build --target $target --release
    END
    DO rust+COPY_OUTPUT --output="[^\./]+/release/[^\./]+"

but cross fails with this error:

              +cross | build=cross target=i686-unknown-linux-musl
              +cross | --> WITH DOCKER RUN --privileged cross build --target $target --release
              +cross | Starting dockerd with data root /var/earthly/dind/f93b09b85d482e3c2c2a9ba24dac0885b16ada45cadeaaa5667074ec0e54ffda/tmp.HMgOjE
              +cross | error: DEPRECATED: future versions of rustup will require --force-non-host to install a non-host toolchain as the default.
              +cross | warning: toolchain '1.75.0-x86_64-unknown-linux-gnu' may not be able to run on this system.
              +cross | warning: If you meant to build software to target that platform, perhaps try `rustup target add x86_64-unknown-linux-gnu` instead?
              +cross | info: syncing channel updates for '1.75.0-x86_64-unknown-linux-gnu'
              +cross | info: latest update on 2023-12-28, rust version 1.75.0 (82e1608df 2023-12-21)
              +cross | info: downloading component 'cargo'
              +cross | info: downloading component 'rust-std'
              +cross | info: downloading component 'rustc'
              +cross | info: installing component 'cargo'
              +cross | info: installing component 'rust-std'
              +cross | info: installing component 'rustc'

              +cross |   1.75.0-x86_64-unknown-linux-gnu installed - (error reading rustc version)

              +cross | error: rustup is not installed at '/tmp/earthly/.cargo'
              +cross | Error: 
              +cross |    0: couldn't install toolchain `1.75.0-x86_64-unknown-linux-gnu`
              +cross |    1: `rustup toolchain add 1.75.0-x86_64-unknown-linux-gnu --profile minimal` failed with exit status: 1
              +cross | earthly debugger | Command /bin/sh -c 'cross build --target $target --release' failed with exit code 1

$ earthly --version
earthly version v0.8.3 70916968c9b1cbc764c4a4d4d137eb9921e97a1f linux/amd64; Ubuntu 23.10 (Mantic Minotaur)

Is there a example with cross available somewhere?

[glehmann]

hey @joepio , I see in #34 that your using cross and earthly with much more success than I do. Would you have a configuration that you could share as an example, or a link to the Earthfile of your project if the sources are public?

[joepio]

Yes! https://github.com/atomicdata-dev/atomic-server/blob/develop/Earthfile

[glehmann]

@joepio thanks a lot, I've been able to make it work with your example :-)

for the reference, the problem disappeared when I switched from the alpine to the slim (debian) variant of the rust image.

That was not all though, I had to clean the target/release directory before each run — somehow some stuff generated during the build was making the next builds fail: https://github.com/glehmann/yage/blob/8446fe3722fb782e6f0aa2b8dfcbd3d00617e3bc/Earthfile#L43

Also I found quite useful to:

• pre install docker and jq in a common base layer to avoid reinstalling them for each platform: https://github.com/glehmann/yage/blob/8446fe3722fb782e6f0aa2b8dfcbd3d00617e3bc/Earthfile#L10
• install cross from binary instead of source — that's much faster: https://github.com/glehmann/yage/blob/8446fe3722fb782e6f0aa2b8dfcbd3d00617e3bc/Earthfile#L15
• fetch the project dependencies in a common base layer to avoid redownloading them for each platform: https://github.com/glehmann/yage/blob/8446fe3722fb782e6f0aa2b8dfcbd3d00617e3bc/Earthfile#L18
• build all the platforms in a single BUILD to let earthly properly deal with the image name on my local computer: https://github.com/glehmann/yage/blob/8446fe3722fb782e6f0aa2b8dfcbd3d00617e3bc/Earthfile#L78
• compute the rust target based on the earthly platform in order to be able to build an image for a single platform with earthly -P --platform linux/s590x +docker: https://github.com/glehmann/yage/blob/8446fe3722fb782e6f0aa2b8dfcbd3d00617e3bc/Earthfile#L24
• pull the cross image from on the host and push it in the dind instance with WITH DOCKER --pull in order to avoid redownloading it many time while working on the build locally: https://github.com/glehmann/yage/blob/8446fe3722fb782e6f0aa2b8dfcbd3d00617e3bc/Earthfile#L40

that's my take on using cross and earthly together. I hope it will be useful for others :-)

[idelvall]

Hi guys, thanks for pushing on this!
I will go through your examples and update the documentation accordingly

[idelvall]

Hi guys, I was able to improve a little @glehmann solution. This is what I did:

• Make the target mount cache ID depends on $TARGETPLATFORM. Add target cache suffix #45
• Now, the cleaning of the target folder is not needed, the builds run in parallel and crate compilation is cached

It's taking more time than expected for me to ship this though the library in a clean way and without losing parallelization, but I didn't want to hold it any longer.

Please let me know your thoughts!

[glehmann]

rust+CROSS works great, thanks 👍