Issue
Image built on Mac OSX with M1 processor, deployed to an EC2 instance. But when scripts are run it yields the error:
standard_init_linux.go:219: exec user process caused: exec format error
Elsewhere on Stackoverflow, this is explained as a mismatch of OS architecture. Sure enough running "uname -m" on EC2 instance shows it to be x86_64, and "docker image inspect" shows the container to have architecture arm64.
Here's what I don't understand. "uname -m" on my Mac shows that to be x86_64 too. So how does the container inherit a different architecture?
More significantly, how do I build an image on my Mac that I can run on EC2?
Docker file is simply
FROM python
WORKDIR /
COPY requirements.txt .
RUN pip install -r requirements.txt
COPY src /src
with src containing, currently, some simple python scripts, executed thus:
docker run container/name python test.py
This works fine on my Mac, but gives the error above when executed on AWS.
Solution
OK. Here's what's happening. My Mac has the new M1 chip and I'm running the Tech Preview version of Docker Desktop. Under the hood the chip has the arm64 architecture, but interrogating it through iTerm and VSCode it claims to be x86_64 instead, hence my confusion when I posted the question. This is probably because both those apps are being quietly run through an Intel simulator behind the scenes and that's what's responding to the uname command.
However, because the processor is really arm64, that's the base architecture when I pull Python images from Docker (I tried lots of different flavours nd version of Python - all with the same results).
To force use of an amd64 AWS-compatible image I changed the first line of the Dockerfile to:
FROM --platform=linux/x86-64 python.
When containers from this image are run on the Mac that causes a warning
WARNING: The requested image's platform (linux/amd64) does not match the detected host platform (linux/arm64/v8) and no specific platform was requested
but it's just that, a warning, and the script runs (presumably by redirecting back through the Intel simulator. The scripts now run without problem (or warning) on the EC2 instance.
Answered By - petercoles Answer Checked By - David Marino (WPSolving Volunteer)