resource-get fails if /tmp and /var are on different file systems

[George Kraft]

If resource-get is called on a system where /tmp and /var are on different file systems, it fails with an error:

ERROR could not download resource: could not replace existing resource directory: rename /tmp/juju-resource-595581070/flannel-amd64 /var/lib/juju/agents/unit-flannel-0/resources/flannel-amd64: invalid cross-device link

The user reporting this used the manual provider. More details in the original report: https://github.com/juju-solutions/charm-flannel/issues/42

[George Kraft (cynerva)]

User is running Juju 2.3.3:

$ juju version
2.3.3-xenial-amd64

[John A Meinel (jameinel)]

I poked around a bit. The code assumes that it can rename the resource into
place from temp.
It should probably handle moving between filesystems or downloading into
the target dir under a temp name.

John
=:->

On Feb 26, 2018 18:05, "George Kraft" <email address hidden> wrote:

> User is running Juju 2.3.3:
>
> $ juju version
> 2.3.3-xenial-amd64
>
> --
> You received this bug notification because you are subscribed to juju.
> Matching subscriptions: juju bugs
> https://bugs.launchpad.net/bugs/1751291
>
> Title:
> resource-get fails if /tmp and /var are on different file systems
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/juju/+bug/1751291/+subscriptions
>

[Gábor Mészáros (gabor.meszaros)]

I got hit by this issue when deploying contrail-controller application.

[Gábor Mészáros (gabor.meszaros)]

The issue probably is that resources context Move uses os.Rename system call (resource/context/context.go:#139:
func (deps contextDeps) Move(target, source string) error {
        // Note that we follow the io.Copy() argument arder here
        // (os.Rename does not).
        return os.Rename(source, target)
}

This under ubuntu does not support moving files across file systems. From man 2 rename:
  EXDEV oldpath and newpath are not on the same mounted filesystem. (Linux permits a filesystem to be mounted at multiple
          points, but rename() does not work across different mount points, even if the same filesystem is mounted on both.)

[Jason Hobbs (jason-hobbs)]

Subscribed to field-high SLA - this is being hit onsite.

[Sandor Zeestraten (szeestraten)]

Hey Vinodhini, I think the comment in #6 was supposed to be in #1634390.

[Vinodhini (vinu-b)]

Thats correct. Thanks Sandor.

[Vinodhini (vinu-b)]

Details of PR committed:
https://github.com/juju/juju/pull/8701