detect docker btrfs backend filesystem

[aojea]

Fixes: #1945,#2050

[aojea]

/assign @BenTheElder
@anfredette can you please verify this solves the issue for fedora33?

[anfredette]

I'm running on a fresh install of Fedora 33 Workstation in which btrfs replaced ext4 as the default filesystem.

kind was failing to start with the following error:
ERROR: failed to create cluster: failed to init node with kubeadm: command "docker exec --privileged ovn-control-plane kubeadm init --skip-phases=preflight --config=/kind/kubeadm.conf --skip-token-print --v=6" failed with error: exit status 1

For reference:
$ docker info --format='{{ index (index .DriverStatus 0) 1 }}'
btrfs

This change fixes my issue.

[k8s-ci-robot]

@anfredette: changing LGTM is restricted to collaborators

In response to this:

I'm running on a fresh install of Fedora 33 Workstation in which btrfs replaced ext4 as the default filesystem.

kind was failing to start with the following error:
ERROR: failed to create cluster: failed to init node with kubeadm: command "docker exec --privileged ovn-control-plane kubeadm init --skip-phases=preflight --config=/kind/kubeadm.conf --skip-token-print --v=6" failed with error: exit status 1

For reference:
$ docker info --format='{{ index (index .DriverStatus 0) 1 }}'
btrfs

This change fixes my issue.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[aojea]

/retest

[aojea]

/retest

[aojea]

/retest

[BenTheElder]

/lgtm
/approve
thanks!

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: anfredette, aojea, BenTheElder

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