Invalid Docker Tags in Custom Docker Images

[Alexhuszagh]

Checklist

• I've looked through the issues and pull requests for similar reports

Describe your issue

Currently, if a project directory (inadvisably) contains invalid characters for a Docker tag, this will cause a build with pre-build hooks or a custom Dockerfile to fail.

A working example available here.

This produces the following errors:

$  cross build --target x86_64-unknown-linux-gnu --verbose
+ cargo metadata --format-version 1 --filter-platform x86_64-unknown-linux-gnu
+ rustc --print sysroot
+ rustup toolchain list
+ rustup target list --toolchain stable-x86_64-unknown-linux-gnu
+ rustup component list --toolchain stable-x86_64-unknown-linux-gnu
+ /usr/bin/docker
+ "/home/ahuszagh/git/CrossPrebuildUppercase" /usr/bin/docker build --label 'org.cross-rs.for-cross-target=x86_64-unknown-linux-gnu' --label 'org.cross-rs.workspace_root=/home/ahuszagh/git/CrossPrebuildUppercase' --tag cross-custom-CrossPrebuildUppercase:x86_64-unknown-linux-gnu-d59ad-pre-build --build-arg 'CROSS_CMD=apt-get update' --build-arg 'CROSS_DEB_ARCH=amd64' --file /home/ahuszagh/git/CrossPrebuildUppercase/target/x86_64-unknown-linux-gnu/Dockerfile.x86_64-unknown-linux-gnu-custom .
invalid argument "cross-custom-CrossPrebuildUppercase:x86_64-unknown-linux-gnu-d59ad-pre-build" for "-t, --tag" flag: invalid reference format: repository name must be lowercase
See 'docker build --help'.
Error: 
   0: could not run container
   1: when building custom image
   2: when pre-building
   3: `/usr/bin/docker build --label 'org.cross-rs.for-cross-target=x86_64-unknown-linux-gnu' --label 'org.cross-rs.workspace_root=/home/ahuszagh/git/CrossPrebuildUppercase' --tag cross-custom-CrossPrebuildUppercase:x86_64-unknown-linux-gnu-d59ad-pre-build --build-arg 'CROSS_CMD=apt-get update' --build-arg 'CROSS_DEB_ARCH=amd64' --file /home/ahuszagh/git/CrossPrebuildUppercase/target/x86_64-unknown-linux-gnu/Dockerfile.x86_64-unknown-linux-gnu-custom .` failed with exit status: 125

Note: CROSS_CMD=apt-get update

What target(s) are you cross-compiling for?

No response

Which operating system is the host (e.g computer cross is on) running?

• macOS
• Windows
• Linux / BSD
• other OS (specify in description)

What architecture is the host?

• x86_64 / AMD64
• arm32
• arm64 (including Mac M1)

What container engine is cross using?

• docker
• podman
• other container engine (specify in description)

cross version

cross 0.2.2 (latest main)

Example

No response

Additional information / notes

No response

[Alexhuszagh]

Since we can't guarantee the workspace root has a package name, it's probably a good idea to just replace any invalid characters (go to_lowercase(), and remove any other invalid characters).