在docker容器中生成一个新进程，该进程从头开始构建

Question

I'm trying to build a minimal docker image (FROM scratch) that contains 2 executable binaries. Both are binaries built with Go. The entrypoint is set to the first one. It takes some data on the image, transforms it using environment variables, starts a new process executing the second binary and pipes the data as an input for the spawned process.

FROM scratch
COPY bin /opt/my-app
ENTRYPOINT ["/opt/my-app/first", "--run", "/opt/my-app/second"]

When I build this image on my Mac, everything works fine. But when it's created it on our build server running linux, the first process cannot start the second one. It fails with an error "fork/exec /opt/my-app/second: no such file or directory". However, "second" binary does exist. In both cases docker engine 1.13.1 is used.

It also works if parent image is changed from scratch to debian:jessie.

Are there any limitations of the scratch image that I'm not aware of?

Answer 1

With a scratch image there will not be a libc (or any shared libs). If it works fine on debian, then I suspect the binary is not statically linked, which is the normal default. Try CGO_ENABLED=0 go build -a -installsuffix cgo as seen here http://www.blang.io/posts/2015-04_golang-alpine-build-golang-binaries-for-alpine-linux/