Currently uncompress converter only supports gzip. This commit fixes it to
support zstd as well.
Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>
When several goroutines call uncompress converter in parallel, the ref name
conflicts each other. This leads to Writer method failing with Unavaliable error
without retry.
For solving this issue, OpenWriter helper should be used. This allows them to
retry in such situations.
Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>
Go example:
```go
opts := []converter.Opt{
// convert Docker media types to OCI ones
converter.WithDocker2OCI(true),
// convert tar.gz layers to uncompressed tar layers
converter.WithLayerConvertFunc(uncompress.LayerConvertFunc),
}
srcRef := "example.com/foo:orig"
dstRef := "example.com/foo:converted"
dstImg, err = converter.Convert(ctx, client, dstRef, srcRef, opts...)
fmt.Println(dstImg.Target)
```
ctr example: `ctr images convert --oci --uncompress example.com/foo:orig example.com/foo:converted`
Go test: `go test -exec sudo -test.root -test.run TestConvert`
The implementation is from https://github.com/containerd/stargz-snapshotter/pull/224,
but eStargz-specific functions are not included in this PR.
eStargz converter can be specified by importing `estargz` package and using `WithLayerConvertFunc(estargz.LayerConvertFunc)` option.
This converter interface will be potentially useful for converting zstd and ocicrypt layers as well.
Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
