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I'm trying to use an x86 Linux host machine to build an arm64 Linux docker image. Despite specifying --platform linux/arm64, I still get errors that suggest I'm not.

Dockerfile:

FROM ubuntu:20.04
SHELL ["/bin/bash", "-c"]
RUN echo 'Hello world'

Command:

docker build --progress plain --platform linux/arm64 -f test.Dockerfile . --no-cache

Output:

Sending build context to Docker daemon  989.2kB
Step 1/2 : FROM ubuntu:20.04
 ---> d25e19480966
Step 2/2 : RUN echo 'Hello world'
 ---> [Warning] The requested image's platform (linux/arm64/v8) does not match the detected host platform (linux/amd64) and no specific platform was requested
 ---> Running in f6c3dc9c965f
standard_init_linux.go:228: exec user process caused: exec format error
The command '/bin/sh -c echo 'Hello world'' returned a non-zero code: 1

Why does docker tell me "and no specific platform was requested" even though I do specify one? Oddly enough, this command works on my M1 Mac regardless of whether I specify linux/amd64 or linux/arm64 as the target platform. I would have expected a Linux-to-Linux build to run more smoothly. What am I missing?

Additional details:

Host machine is an EC2 instance running the Amazon Linux 2 AIM (amzn2-ami-kernel-5.10-hvm-2.0.20220606.1-x86_64-gp2)

$ docker --version
Docker version 20.10.13, build a224086

$ uname -m
x86_64

I installed qemu manually via

sudo yum install qemu-kvm -y
jkelle
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  • Does running `export DOCKER_BUILDKIT=1` first fix it? – BMitch Jul 29 '22 at 01:16
  • `docker buildx build --platform ...` seemed to helped here: https://stackoverflow.com/questions/71000707/docker-get-started-warning-the-requested-images-platform-linux-arm64-v8-doe – felice Jul 30 '22 at 13:53

0 Answers0