Function Fetch

cmd/ctr/commands/content/fetch.go:157–209

Fetch loads all resources into the content store and returns the image

(ctx context.Context, client *containerd.Client, ref string, config *FetchConfig)

// Fetch loads all resources into the content store and returns the image
func Fetch(ctx context.Context, client *containerd.Client, ref string, config *FetchConfig) (images.Image, error) {
	ongoing := NewJobs(ref)

	if config.TraceHTTP {
		ctx = httpdbg.WithClientTrace(ctx)
	}

	pctx, stopProgress := context.WithCancel(ctx)
	progress := make(chan struct{})

	go func() {
		if config.ProgressOutput != nil {
			// no progress bar, because it hides some debug logs
			ShowProgress(pctx, ongoing, client.ContentStore(), config.ProgressOutput)
		}
		close(progress)
	}()

	h := images.HandlerFunc(func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
		ongoing.Add(desc)
		return nil, nil
	})

	log.G(pctx).WithField("image", ref).Debug("fetching")
	labels := commands.LabelArgs(config.Labels)
	opts := []containerd.RemoteOpt{
		containerd.WithPullLabels(labels),
		containerd.WithResolver(config.Resolver),
		containerd.WithImageHandler(h),
	}
	opts = append(opts, config.RemoteOpts...)

	if config.AllMetadata {
		opts = append(opts, containerd.WithAllMetadata())
	}

	if config.PlatformMatcher != nil {
		opts = append(opts, containerd.WithPlatformMatcher(config.PlatformMatcher))
	} else {
		for _, platform := range config.Platforms {
			opts = append(opts, containerd.WithPlatform(platform))
		}
	}

	img, err := client.Fetch(pctx, ref, opts...)
	stopProgress()
	if err != nil {
		return images.Image{}, err
	}

	<-progress
	return img, nil
}

// ShowProgress continuously updates the output with job progress
// by checking status in the content store.