Enable build for ARM processor architectuere

[lilachic]

To be able to run the containers at Mac M1 processor we need to provide the container images build for ARM

Changes:

• Dockerfile

  • Add variable to pass custom made EMSDK image for building docker-container-crypt4gh Docker image for ARM.

• README

  • Add instruction to use build arguments for custom build Docker image.

[csc-felipe]

Nice work with figuring out how to add support for new macs. I was thinking that if we can specify the image, perhaps we don't need two separate variables, EMSDK_IMAGE and EMSCRIPTEN_VERSION. I think it could be better user experience for this to have only EMSDK_IMAGE. or what do you think?

[lilachic]

Nice work with figuring out how to add support for new macs. I was thinking that if we can specify the image, perhaps we don't need two separate variables, EMSDK_IMAGE and EMSCRIPTEN_VERSION. I think it could be better user experience for this to have only EMSDK_IMAGE. or what do you think?

good point. For building ARM we need to select locally for ARM built emsdk, that is why the option is added to use an image from custom registry.

The version of emsdk in Dockerfile was defined there, And I wanted to keep the option choosing the version of emsdk separate to the image. Not sure if we need this?

Hopefully in future we can use images build for multiplatform, same image containing both AMD and ARM versions. Then we could continue to use either official images or custom build emsdk images if needed?

[blankdots]

Hopefully in future we can use images build for multiplatform, same image containing both AMD and ARM versions. Then we could continue to use either official images or custom build emsdk images if needed?

sounds ok to me, and when this emscripten-core/emsdk#1211 is done maybe we can automate this somehow.

Environment vars, no preference there