Support for ARM64 for docker image

[munyoudoum]

Currently only see linux/amd64 on https://hub.docker.com/r/megalinter/megalinter/tags

It would be amazing to have arm64 also

Thanks

[nvuillam]

It's probably possible :) https://medium.com/swlh/using-github-actions-to-build-arm-based-docker-images-413a8d498ee

But will take some time if I have to do it myself because of my little available time these days ^^

We could have "mirror" images with -arm , like megalinter/megalinter:arm-v5 , arm-beta , etc ...

Do you have Github Actions knownledge ? I would glady accept a PR :)

[echoix]

Today I tried to build an arm64 docker image.

The solution to build multiple docker images (same name, but different CPU architectures combined) is to use buildx.
Since it is running in a shell script and not in pure GitHub action, then the setup is to do

docker buildx create --use

Then, replacing

docker build --no-cache --build-arg "BUILD_DATE=${BUILD_DATE}" --build-arg "BUILD_REVISION=${BUILD_REVISION}" --build-arg "BUILD_VERSION=${BUILD_VERSION}" -t "${CONTAINER_URL}:${IMAGE_VERSION}" -f "${DOCKERFILE_PATH}" . 2>&1

with

docker buildx build --platform linux/amd64,linux/arm64 --no-cache --build-arg "BUILD_DATE=${BUILD_DATE}" --build-arg "BUILD_REVISION=${BUILD_REVISION}" --build-arg "BUILD_VERSION=${BUILD_VERSION}" -t "${CONTAINER_URL}:${IMAGE_VERSION}" -f "${DOCKERFILE_PATH}" . 2>&1

should do the work (replacing all the places with build by buildx build and platforms.

However, there is some prep work to make everything work.
Currently, in the Dockerfile some tools are downloaded with an explicit url targeting x86_64 or amd64, etc. There must be a way of defining different urls or download links per tool. Not all tools name arm64 the same way, so no variable in URL works for everyone (some call it aarch64 for example).
Also, some tools, like dotenv-linter have problems building for arm64 on Docker because of a long-standing problem of a rust crypto library, Ring. I tried to see if I could fix it myself, but it seems harder than it seems.

I also tried building the Dockerfile locally on a Raspberry Pi 4, but it failed when it came time to pull FROM checkmarx/kics:alpine as kics since my Raspberry Pi 4 was not installed on a 64-bit OS, so it reported armv7l, asking linux/arm/v7, which they don't publish.

So, I'll try to come back with a TODO list of linters to fix the install to get a building image, and one day we could talk about actual failing linters. In the meantime, some prep work to integrate having different URL installers should be done. Most of the Docker tools are ok, especially when they target only alpine, or many arch are available.

[nvuillam]

Thank a lot for your analysis :)

About not compliant linters, we could eventually flag them in descriptors so they are simply not added within arm64 images

Story to be continued... :)

[echoix]

I just hope that to start, at least one flavour would have all linters working... We'll see :)

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[echoix]

I'd like to keep it as a milestone task, but it'll be over the next two months though... I'm still thinking it out regularly

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[natpicone]

really needed

[echoix]

@natpicone What linters or flavours do you use in priority? It is not a simple task to have MegaLinter on arm, since we would have to ask for changes in many of the included projets.
Pure Python linters should run without any problems, but we still need to figure out how to built multi arch image Dockerfiles.