containers / common

I'm told the libimage.ImageConfigFromChanges() function is broken. Reproducer:

(The exact image used doesn't matter)

$ podman pull registry.fedoraproject.org/fedora:latest
$ podman save registry.fedoraproject.org/fedora:latest > asdf.tar
$ podman import -c 'ENV=PS1=$(whoami) $(hostname) $ ' asdf.tar

Output:

Error: invalid change "ENV=PS1=$(whoami) $(hostname) $ " - invalid instruction ENV=PS1=$(WHOAMI)

What does work is:

$ podman import -c 'ENV "PS1=$(whoami) $(hostname) $ "' asdf.tar

Note, without the double-quotes it imports the image, but fails to preserve the trailing space:

$ podman import -c 'ENV PS1=$(whoami) $(hostname) $ ' asdf.tar
$ podman image inspect --format '{{.Config.Env}}' 1bde4dd5da92
PS1=$(whoami) $(hostname) $]

(Space at the end is lost)

Looking at the code this seems expected. The code assume a Dockerfile like syntax. INSTRUCTION followed by a spcae then the arguments. It only falls back to the equal sign when it did not find any space.

common/libimage/image_config.go

Lines 39 to 51 in 9f28ae5

    
           // First, let's assume proper Dockerfile format - space 
        
           // separator between instruction and value 
        
           split := strings.SplitN(change, " ", 2) 
        
           if len(split) != 2 { 
        
           	split = strings.SplitN(change, "=", 2) 
        
           	if len(split) != 2 { 
        
           		return nil, fmt.Errorf("invalid change %q - must be formatted as KEY VALUE", change) 
        
           	} 
        
           } 
        
           outerKey := strings.ToUpper(strings.TrimSpace(split[0])) 
        
           value := strings.TrimSpace(split[1])

The code also always trims space so that part is expected as well. The podman import and podman commit man page do not really explain the format. They only show some examples so I understand the confusion.

In any case I do not see a good way to change the code. I would say this should just be documented better.

I would say this should just be documented better.

I would be okay with that. The confusing parsing caught at least one user off-guard - meaning, there are probably 5-more users that didn't report the problem.

The first place Nalin and I turned to look (the man page) was (as you've seen) not very helpful. So a docs-update may very well be good'nuff of a fix.

I only hesitate shortly, before to suggesting the docs should focus on using a space-separator and never = - for consistency.

	// First, let's assume proper Dockerfile format - space
	// separator between instruction and value
	split := strings.SplitN(change, " ", 2)

	if len(split) != 2 {
	split = strings.SplitN(change, "=", 2)
	if len(split) != 2 {
	return nil, fmt.Errorf("invalid change %q - must be formatted as KEY VALUE", change)
	}
	}

	outerKey := strings.ToUpper(strings.TrimSpace(split[0]))
	value := strings.TrimSpace(split[1])

Image-import change handles space's badly