CODEWITHSUNDEEP
docker
Bert Kellerman
Bert Kellerman

Reputation: 1629

Docker: Can't access binary copied to certain images

I am trying to access a binary COPYed from the migrate container. When I COPY to python:3.7-alpine it works, but when I COPY to debian:buster-slim it can't be found.

Minimum steps to reproduce:

1.Create Dockerfile.test

FROM migrate/migrate:v4.6.2 AS migrate
FROM python:3.7-alpine
COPY --from=migrate /migrate /
CMD "/migrate"
  1. Build and run. This works.
docker build . -t migrate_test -f Dockerfile.test
docker run --name migrate_test migrate_test:latest

Usage: migrate OPTIONS COMMAND [arg...]
       migrate [ -version | -help ]
  1. Stop and remove container
docker stop migrate_test;docker rm migrate_test;
  1. Change image in Dockerfile.test
FROM migrate/migrate:v4.6.2 AS migrate
FROM debian:buster-slim
COPY --from=migrate /migrate /
CMD "/migrate"
  1. Build and run. This doesn't work
docker build . -t migrate_test -f Dockerfile.test
docker run --name migrate_test migrate_test:latest

/bin/sh: 1: /migrate: not found

Upvotes: 1

Views: 2198

Answers (1)

larsks
larsks

Reputation: 311606

It looks like you have things working, but just to clarify the situation for other folks who might find your question:

The issue is that the migrate/migrate:v4.6.2 is built on the Alpine image, which uses MUSL libc, whereas most other distributions use glibc. You're getting the "not found" message because the kernel is looking for the dynamic loader whose path is embedded in the image, as we see with the ldd command:

/ # ldd /migrate
        /lib/ld-musl-x86_64.so.1 (0x7f9e42ebd000)
        libc.musl-x86_64.so.1 => /lib/ld-musl-x86_64.so.1 (0x7f9e42ebd000)

This binary will be available on Alpine-based image, but not on images from Debian, Ubuntu, Fedora, CentOS, etc. One option is to simply copy over the necessary loader in your Dockerfile:

FROM migrate/migrate:v4.6.2 AS migrate
FROM debian:buster-slim
COPY --from=migrate /migrate /
COPY --from=migrate /lib/ld-musl-x86_64.so.1 /lib/ld-musl-x86_64.so.1

CMD "/migrate"

Another solution would be to rebuild the migrate command for your target distribution.

Upvotes: 2

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