Hi,

carton doesn't find the cpanfile when invoked from the root / of a filesystem. If a cpanfile exists, carton says it can't locate a cpanfile:

root@3f57344871f4:/# carton install
Can't locate cpanfile: (cpanfile)

This happened to me when building inside a docker container, since debian stretch images workdir is /. To reproduce:

docker run --rm -ti debian:stretch /bin/bash
root@3f57344871f4:/# apt-get update ; apt-get -y upgrade ; apt-get install -y carton
root@3f57344871f4:/# cat - > cpanfile <<EOF
requires 'JSON::PP';
EOF
root@3f57344871f4:/# carton install
Can't locate cpanfile: (cpanfile)

I don't think that invoking carton in the filesystem root is specially wise, but it happens by default (and I can imagine lots more images have that default) and the error is very misleading.

Note that this happens with Debian packaged carton, as well as v1.0.34 from CPAN.