TestContainerStartedAndStopped cannot create mock container on ppc64el/arm64 xenial/wily

[Curtis Hovey]

As seen at
     http://reports.vapour.ws/releases/issue/56d1e94d749a5621808fcf26

1.25 and several 2.0 branches cannot create a mock container to test lxc. This issue affects the minority series-archs. arm64 and ppc64el (on both wily and xenial), and centos7-amd64 fail.

[Cheryl Jennings (cherylj)]

This test fails on centos because of the losetup / path issue:
[LOG] 0:10.940 ERROR juju.container.lxc failed to detach loop devices from lxc container: listing loop devices: exec: "losetup": executable file not found in $PATH

It fails on other series /arches because it cannot find tools to start the container with:
[LOG] 0:06.101 ERROR juju.provisioner cannot start instance for machine "0/lxc/0": need tools for arch arm64, only found [amd64]

This happens because we seed the tools with the current series / arch, but use the default series when creating a container ("trusty"). We need to add the trusty tools for the current arch.

[Cheryl Jennings (cherylj)]

PR for master: https://github.com/juju/juju/pull/4579

[Cheryl Jennings (cherylj)]

1.25 PR: https://github.com/juju/juju/pull/4586

[Cheryl Jennings (cherylj)]

Updated 1.25 PR: https://github.com/juju/juju/pull/4592

[John A Meinel (jameinel)]

Looking at https://github.com/juju/juju/blob/master/worker/provisioner/provisioner_test.go#L114

It appears that we hard code "amd64" as the default constraints everywhere. It is probably really hard to start an AMD64 container on PowerPC.