Define an error to allow an external reference

[zhangguanzhang]

Fixes: containers/podman#7337
more detail could see containers/podman#7337 (comment)
Signed-off-by: zhangguanzhang [email protected]

[rhatdan]

@vrothberg @mtrmac PTAL

[vrothberg]

I think we need to fix it in podman.

$ podman load -i FOO.tar name:tag is supposed to load the image in FOO.tar and the tag it as name:tag.

[zhangguanzhang]

I think we need to fix it in podman.

$ podman load -i FOO.tar name:tag is supposed to load the image in FOO.tar and the tag it as name:tag.

you could see this containers/podman#7337 (comment)
I use the dlv to debug this and found the reason, so I commit this pr

[mtrmac]

I’m afraid I have no idea what is the problem, the solution, or how this makes any sense.

• Why make a check for len(index.Manifests), and use the [0] member inside a loop iterating through array?
• If the user asks for a specific ref.image, how does it make sense to return an entry that does not have that name?
• How does it make sense for a “find” operation to edit the data?

If this is to influence Podman’s heuristics for deciding how to tag the result of a pull, those are entirely up to Podman and c/image is trying fairly hard to stay away.

[zhangguanzhang]

I change it，I need this error type to judge in podman

[mtrmac]

I’m afraid I have no idea what is the problem, the solution

I can’t see how this relates to the linked Podman issue at all. If Podman is using file names instead of other data it was supplied, why can’t it just stop doing that?

[zhangguanzhang]

$ podman pull alpine
$ podman save --format oci-archive alpine:latest >| /tmp/FOO.tar

this will be ok

$ podman load -i /tmp/FOO.tar 

and this image name will be docker.io/library/alpine:latest, it will run into this line https://github.com/containers/image/blob/master/oci/layout/oci_transport.go#L190

but if use a name to override, afer this , the image's name should be localhost/foo:latest

$ podman load -i /tmp/FOO.tar foo 
Error: error pulling "foo": unable to pull dir:/tmp/FOO.tar: error determining pull goal for image "dir:/tmp/FOO.tar": error parsing dest reference name "localhost/tmp/FOO.tar": error parsing named reference "localhost/tmp/FOO.tar": invalid reference format: repository name must be lowercase

it does not run ok in the function in https://github.com/containers/podman/blob/master/libpod/runtime_img.go#L288-L294
Because in this case, https://github.com/containers/image/blob/master/oci/layout/oci_transport.go#L205 ref.image is localhost/foo:latest, it is not equal to docker.io/library/alpine:latest

[mtrmac]

Because in this case, https://github.com/containers/image/blob/master/oci/layout/oci_transport.go#L205 ref.image is localhost/foo:latest, it is not equal to docker.io/library/alpine:latest

So what’s actually wrong about that situation? If the ref is for $path:foo, and foo does not exist in the index, that’s that.

• As far as the end user is concerned, what should happen instead?
• How does that difference in actual vs. expected behavior manifest at the c/image API boundary?
• How does adding a recognizable error type help? What is Podman going to do with that error? (I guess “try again with some other reference — but then why is it trying two ways instead of just the correct way?)

(Perhaps see also the conversation around containers/podman#6811 (comment) , but I suspect the questions I have are at a more basic level.)

[zhangguanzhang]

I think when len(index.Manifests) == 1 and ref.image != ""， the image's name will be the ref.image after load the oci-archive file

[rhatdan]

@mtrmac What is your latest feeling on this?

[mtrmac]

containers/podman#7386 (comment) – I don’t really understand what’s going on, even what’s wrong, my best guess is that Podman is internally confused about the meaning of the “name” parameter.