Publish Docker images for ARM architecture

[ngosang]

Publish Docker images for ARM architecture in https://hub.docker.com/r/healthchecks/healthchecks/tags

GitHub Actions example => https://github.com/ngosang/urbackup-exporter/blob/master/.github/workflows/release-docker.yml#L103

[cuu508]

Building cryptography on arm/v7 throws an error, not sure how to fix it:

https://github.com/healthchecks/healthchecks/runs/3866973629?check_suite_focus=true#step:7:3563

I can also reproduce the problem locally:

cp docker/Dockerfile .
docker buildx build --platform linux/arm/v7 -t arm-build .

It produces the same error message:

#11 226.6   generating cffi module 'build/temp.linux-armv7l-3.9/_openssl.c'
#11 226.6   creating build/temp.linux-armv7l-3.9
#11 226.6   running build_rust
#11 226.6       Updating crates.io index
[...]
#11 226.6   subprocess.CalledProcessError: Command '['cargo', 'metadata', '--manifest-path', 'src/rust/Cargo.toml', '--format-version', '1']' died with <Signals.SIGSEGV: 11>.
#11 226.6   ----------------------------------------
#11 226.6   ERROR: Failed building wheel for cryptography

[ngosang]

@cuu508 take a look here, they are skipping that dependency with an environment variable => https://github.com/linuxserver/docker-healthchecks/blob/master/Dockerfile.aarch64

Since linuxserver provides Docker images for AMD64, ARM and ARM64 it is possible to archive.

[cuu508]

Unfortunately CRYPTOGRAPHY_DONT_BUILD_RUST does not work any more with cryptography >= 35.0.0, see #565

[ngosang]

They are publishing latest release (1.22.0) for ARM using the Dockerfile from my previous comment.
https://hub.docker.com/r/linuxserver/healthchecks/tags
Those images are working fine.

[cuu508]

They install dependencies like so:

pip3 install --no-cache-dir --find-links https://wheel-index.linuxserver.io/alpine/ -r requirements.txt 

If you look at https://wheel-index.linuxserver.io/alpine/, it has a prebuilt wheel for cryptography==35.0.0, armv7l. I guess that's how they get around building it from source and hitting the rust issue.

[cuu508]

Found issues with people hitting the same error: pyca/cryptography#6347 and docker/buildx#395 (comment)

[cuu508]

To work around the cryptography-rust-buildx-qemu issue I updated the Dockerfile to use piwheels.org repo (but only when the architecture is armhf): 1b0f5e9

I released v1.23.1 with these changes. Three architectures are now available on Docker Hub linux/amd64, linux/arm/v7 and linux/arm64. I have tested the first two and they seem to nominally work.

[ngosang]

@cuu508 Thank you, that was fast!
I'm still using the Linuxserver Docker image in production because is critical for me, but I will use the official Docker image eventually. I will report any issue then.