Test program to content service.

test-content-readat.go

package main

import (
	"context"
	"fmt"

	"github.com/containerd/containerd"
	"github.com/containerd/containerd/images"
	"github.com/containerd/containerd/namespaces"
)

func main() {
	var (
		ctx        = context.Background()
		background = namespaces.WithNamespace(ctx, "background")
		address    = "/run/containerd/containerd.sock"
	)

	client, err := containerd.New(address)
	if err != nil {
		fmt.Println(err)
		return
	}

	cs := client.ContentStore()
	//Pull Image
	image, err := client.Pull(background, "docker.io/library/redis:alpine", containerd.WithPullUnpack)
	if err != nil {
		fmt.Println(err)
		return
	}

	index := image.Target()
	manifiests, err := images.Children(background, cs, index)
	if err != nil {
		fmt.Println(err)
		return
	}
	for _, manifest := range manifiests {
		Children, err := images.Children(background, cs, manifest)
		if err != nil {
			fmt.Println(err)
			return
		}

		for _, desc := range Children {
			ra, err := cs.ReaderAt(background, desc)
			if err != nil {
				fmt.Println(err)
				return
			}

			//Allocate more then size of data
			p := make([]byte, ra.Size()+int64(10))

			readData, err := ra.ReadAt(p, 0)
			if err != nil {
				fmt.Println("Blob read error ", err)
			}
			fmt.Println(readData, p[:10])
			ra.Close()
		}
	}

	return
}