Implement sshfs volumes for podman machine

[afbjorklund]

What this PR does / why we need it:

This adds sshfs volume support through sshocker, for platforms without virtfs.

https://github.com/lima-vm/sshocker

It also works for remote servers, beyond those created by podman machine

For #8016

How to verify it

No tests for podman machine yet. Test manually using --volume-driver=sshfs

Which issue(s) this PR fixes:

None

Special notes for your reviewer:

Continuation of PR #11454 which should go first, but has been waiting for a while.

• Implement virtfs volumes for podman machine #11454

[openshift-ci]

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[afbjorklund]

The dependency on an internal sshocker binary could be replaced,
with a library dependency on "github.com/lima-vm/sshocker/pkg/sshocker"

https://github.com/lima-vm/sshocker/blob/master/cmd/sshocker/run.go

But the ssh config file is still needed, for populating "ssh.SSHConfig" struct

[AkihiroSuda]

Seems like the license for osxfuse has changed: Homebrew/homebrew-core#64491

cc @baude

How is it relevant to this PR?
sshocker doesn’t use osxfuse

[afbjorklund]

sshocker doesn’t use osxfuse

Sorry, my bad. Confused the "sshfs" and the "reverse-sshfs" again, after the renaming.

I think it was relevant for docker-machine mount and podman-machine mount, only...

[afbjorklund]

Apparently this does not work out-of-the-box with Fedora CoreOS, since it only allows user:

[root@localhost ~]# more /etc/fuse.conf
# mount_max = 1000
# user_allow_other
[root@localhost ~]# ls -l /mnt/
ls: cannot access '/mnt/podman': Permission denied
total 0
d????????? ? ? ? ?            ? podman

Also have to special-case /mnt, since it is a symbolic link (which sshocker doesn't handle)

• Waiting for mount doesn't work when target is a symlink lima-vm/sshocker#18

---

For lima, this FUSE configuration is handled with cloud-init:

https://github.com/lima-vm/lima/blob/v0.8.0/pkg/cidata/cidata.TEMPLATE.d/boot/30-install-packages.sh#L4_L11

	# Modify /etc/fuse.conf to allow "-o allow_root"
	if [ "${LIMA_CIDATA_MOUNTS}" -gt 0 ]; then
		if ! grep -q "^user_allow_other" /etc/fuse.conf; then
			echo "user_allow_other" >>/etc/fuse.conf
		fi
	fi

[afbjorklund]

Apparently the library only supports Run, and not Start. But maybe can use other ssh flags ? (like -n)

package exec // import "os/exec"

func (c *Cmd) Run() error
    Run starts the specified command and waits for it to complete.

func (c *Cmd) Start() error
    Start starts the specified command but does not wait for it to complete.

func (c *Cmd) Wait() error
    Wait waits for the command to exit and waits for any copying to stdin or
    copying from stdout or stderr to complete.

    The command must have been started by Start.

https://github.com/lima-vm/sshocker/blob/master/pkg/sshocker/sshocker.go

• Add option to just open tunnels without any command lima-vm/sshocker#19

EDIT: Needs more support, like keeping track of the sleeping ssh connection and so on.

In lima, there are "agents" running on the host and in the guest that keeps track of this.

[afbjorklund]

Will revisit next year, once the basic volume support is in. Too much hassle handle multiple long-lived branches.

The sshocker call is pretty basic, the main issue is that the ssh config is hidden behind the podman "connection".

ssh -F ~/.config/containers/podman/machine/qemu/podman-machine-default.config \
    podman-machine-default

sshocker -F ~/.config/containers/podman/machine/qemu/podman-machine-default.config \
         -v /tmp/podman:/var/mnt/podman podman-machine-default

Currently "host:port" is required, rather than "name":

• Specifying the host and port in config doesn't work lima-vm/sshocker#21

[afbjorklund]

Opened bugs on sshocker for the outstanding issues, you can use lima for podman meanwhile.

limactl start https://raw.githubusercontent.com/lima-vm/lima/master/examples/podman.yaml