load: import all platforms (--all-platforms)

[cpuguy83]

Currently if you try to import a non-native image the blobs will get
GC'd and unpack fails with with "not found" on the blobs.

Import doesn't really have a way to select which platforms to important,
so I don't think it makes sense to make this optional. After all the tar
could just be modified with the desired platforms.

[AkihiroSuda]

This should be gated with --all-platforms as in nerdctl image convert --all-platforms OLD NEW .

nerdctl/cmd/nerdctl/image_convert.go

Lines 80 to 89 in 06f236d

	// platform flags
	&cli.StringSliceFlag{
	Name: "platform",
	Usage: "Convert content for a specific platform",
	Value: &cli.StringSlice{},
	},
	&cli.BoolFlag{
	Name: "all-platforms",
	Usage: "Convert content for all platforms",
	},

In addition to nerdctl load, nerdctl pull should follow the same semantics, though PR for nerdctl pull can be worked out separately
(Obviously nobody wants all the platforms to be pulled by default)

[fahedouch]

Hello,

@cpuguy83 I do not agree with you. the import retrieves the platform to import from the client which is platforms.DefaultStrict()

the platform is applied on the client here :

nerdctl/cmd/nerdctl/load.go

Line 58 in 47a4917

client, ctx, cancel, err := newClient(clicontext, containerd.WithDefaultPlatform(platforms.DefaultStrict()))

so then the import function will get it and initialize the platformMatcher with platforms.DefaultStrict() :
https://github.com/containerd/containerd/blob/fda782a7b941de5438e4fbbd38675bf23b69304b/import.go#L128

I agree with @AkihiroSuda making all-platforms by default is not the it is not the best choice. I think we should keep platforms.DefaultStrict() and add --all-platforms flag

[cpuguy83]

Either way is fine.
My main point is the user is supplying the tar to import. It seems strange to not import the whole tar, especially since it seems to be importing them anyway.

[cpuguy83]

Added the --all-platforms flag.

[fahedouch]

LGTM

[AkihiroSuda]

"false by default" can be removed, as urfave/cli/v2 appends (default: false) automatically

[AkihiroSuda]

Thanks