Podman Image SCP transfer patch

[cdoern]

Fixed syntax so that podman image scp transfer works with no user specified.

This command can only be executed as root so to obtain the default user, I searched for
the SUDO_USER environmental variable.

If that is not found, we error out and inform the user
to set this variable and make sure they are running as root.

the two functional syntax forms are now:

sudo podman image scp root@localhost::IMAGE

and

sudo podman image scp root@localhost::IMAGE USER@localhost::

Signed-off-by: cdoern [email protected]

[rhatdan]

Still blows up for me.

 ./bin/podman image scp myimage root@localhost::
panic: runtime error: index out of range [1] with length 1

goroutine 1 [running]:
github.com/containers/podman/v3/cmd/podman/images.parseArgs(0xc0003e1aa0, 0x2, 0x2, 0xc00035cc00, 0x1f4a170, 0xc00059c6f0, 0x0)
	/home/dwalsh/podman/cmd/podman/images/scp.go:303 +0x1625
github.com/containers/podman/v3/cmd/podman/images.scp(0x298b040, 0xc0003e1aa0, 0x2, 0x2, 0x0, 0x0)
	/home/dwalsh/podman/cmd/podman/images/scp.go:91 +0x245
github.com/spf13/cobra.(*Command).execute(0x298b040, 0xc00003c0d0, 0x2, 0x2, 0x298b040, 0xc00003c0d0)
	/home/dwalsh/podman/vendor/github.com/spf13/cobra/command.go:856 +0x472
github.com/spf13/cobra.(*Command).ExecuteC(0x299acc0, 0xc0000400d8, 0x19f14e0, 0x2a5df10)
	/home/dwalsh/podman/vendor/github.com/spf13/cobra/command.go:974 +0x375
github.com/spf13/cobra.(*Command).Execute(...)
	/home/dwalsh/podman/vendor/github.com/spf13/cobra/command.go:902
github.com/spf13/cobra.(*Command).ExecuteContext(...)
	/home/dwalsh/podman/vendor/github.com/spf13/cobra/command.go:895
main.Execute()
	/home/dwalsh/podman/cmd/podman/root.go:91 +0xe7
main.main()
	/home/dwalsh/podman/cmd/podman/main.go:39 +0x92

[rhatdan]

$ ./bin/podman image scp root@localhost::alpine .
Error: could not save image as specified: alpine: image not known
$ ./bin/podman image scp root@localhost::alpine
Error: could not save image as specified: alpine: image not known

[cdoern]

@rhatdan The transfer command has to be run as root which explains the alpine not found error, and the syntax you're trying to use of podman image scp image root@localhost:: also does nothing because we can't transfer images to root which is that that is trying to do.

But that panic should not be happening even with the incorrect arguments, I'll take another look.

[rhatdan]

Why would I need to run as root? This makes the command a lot less useful if it needs to be run as root.
Why wouldn't it work with sudo and move images back and forth?

If this only works as root, then it should have failed with that message.

[cdoern]

@rhatdan sorry, I am confused, are you running those commands you are showing me using sudo? The command was designed to be run using sudo. Any attempt to invoke sudo within the rootless proces led to the following error:

sudo: /etc/sudo.conf is owned by uid 65534, should be 0
sudo: /etc/sudo.conf is owned by uid 65534, should be 0
sudo: error in /etc/sudo.conf, line 0 while loading plugin "sudoers_policy"
sudo: /usr/libexec/sudo/sudoers.so must be owned by uid 0
sudo: fatal error, unable to load plugins
Error: exit status 1

I can try to mess around with this again but that led me down the rabbit hole of creating a new user NS which most people agreed was too complicated for the task at hand.

[rhatdan]

I am not running this command as sudo. I am running it as a rootless user.
There is nothing in the man page about sudo and there is nothing to tell me I did anything wrong. So for now, lets fix the man page and make podman image scp blowup if I run it as non root, in this circumstance.
And then let's fix the fact that I have to run it with sudo.

[rhatdan]

I think we can figure out how to not enter the user namespace in the situation where we want to use sudo. But for now fix the crash.

[cdoern]

I think we can figure out how to not enter the user namespace in the situation where we want to use sudo. But for now fix the crash.

okay, I will look into this a bit because I agree it is much less useful this way.

[umohnani8]

Looks like this is ready - LGTM
@rhatdan @mheon PTAL

[rhatdan]

Still segfaulting:

./bin/podman image scp alpine root@localhost::alpine
panic: runtime error: index out of range [1] with length 1

goroutine 1 [running]:
github.com/containers/podman/v3/cmd/podman/images.parseArgs(0xc0002d2560, 0x2, 0x2, 0xc0001a3800, 0x1f47230, 0xc000010ad8, 0x0)
	/home/dwalsh/podman/cmd/podman/images/scp.go:299 +0x1625
github.com/containers/podman/v3/cmd/podman/images.scp(0x2983060, 0xc0002d2560, 0x2, 0x2, 0x0, 0x0)
	/home/dwalsh/podman/cmd/podman/images/scp.go:91 +0x245
github.com/spf13/cobra.(*Command).execute(0x2983060, 0xc000114080, 0x2, 0x2, 0x2983060, 0xc000114080)
	/home/dwalsh/podman/vendor/github.com/spf13/cobra/command.go:856 +0x472
github.com/spf13/cobra.(*Command).ExecuteC(0x2992ce0, 0xc000138030, 0x19ef3e0, 0x2a55f30)
	/home/dwalsh/podman/vendor/github.com/spf13/cobra/command.go:974 +0x375
github.com/spf13/cobra.(*Command).Execute(...)
	/home/dwalsh/podman/vendor/github.com/spf13/cobra/command.go:902
github.com/spf13/cobra.(*Command).ExecuteContext(...)
	/home/dwalsh/podman/vendor/github.com/spf13/cobra/command.go:895
main.Execute()
	/home/dwalsh/podman/cmd/podman/root.go:91 +0xe7
main.main()
	/home/dwalsh/podman/cmd/podman/main.go:39 +0x92

[cdoern]

@rhatdan I am not getting that error but I am pushing a different fix for syntax, let me know if that fixes your issue.

[rhatdan]

That is better at least gets rid of the crash, but the error makes not sense to a human being.

Error: cannot transfer images from any user besides root using sudo: invalid argument

As a user of this tool, I would have no idea what that meant.

[rhatdan]

Ok I will merge, but this is still needs to work for rootless users.

/approve
/lgtm

[openshift-ci]

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