Pulling image fails with status 500 (invalid cross-device link)

[ryangalamb]

When trying to work through the "Pull and run a unikernel without building on VirtualBox" tutorial, running unik pull --image PythonExample --provider virtualbox fails with this message:

FATA[0059] [client/images.go:107] failed with status 500: [virtualbox/pull_image.go:43] renaming tmp image to /home/rjmill/.unik/virtualbox/images/PythonExample/boot.vmdk: {rename /tmp/tmp-pull-image-PythonExample035683735 /home/rjmill/.unik/virtualbox/images/PythonExample/boot.vmdk: invalid cross-device link}

Looking at the code where it fails, the daemon is trying to use os.Rename to move the image from my /tmp directory to somewhere in my /home directory.

The problem appears to be that my /home directory is on a separate partition from my /tmp directory. And using os.Rename to move a file between partitions doesn't work (hence the invalid cross-device link at the end of the error message.)

Other potentially useful info:

• I'm running Arch Linux.
• I've successfully built and run a node.js rump kernel on VirtualBox using these instructions.
• I found this issue in the ginkgo project, where they ran into what looks like the same problem and seem to have solved it

I'm not super familiar with Go yet, but this issue seems straightforward enough. I'll try taking a stab at this tomorrow and hopefully have a PR for this.

[ilackarms]

an easy workaround for this is to change the default directory that Go uses to store temporary files by overriding the default value of TMPDIR with another directory. e.g.

export TMPDIR=/path/to/custom/tmp/
unik daemon [...args]

I think a patch to fix this should be pretty simple. We already default to using ~/.unik/tmp on OSX because of an issue with Docker Machine there. We can simply make this the norm for both OSes

edit: Patched, this should be fixed now on master