func main()

in example/ecr-pull/main.go [39:115]
68 lines of code
12 McCabe index (conditional complexity)

func main() {
	ctx := namespaces.NamespaceFromEnv(context.Background())

	if len(os.Args) < 2 {
		log.G(ctx).Fatal("Must provide image to pull as argument")
	} else if len(os.Args) > 2 {
		log.G(ctx).Fatal("Must provide only the image to pull")
	}

	ref := os.Args[1]

	parallelism := defaultParallelism
	parseEnvInt(ctx, "ECR_PULL_PARALLEL", &parallelism)

	enableDebug := defaultEnableDebug
	parseEnvInt(ctx, "ECR_PULL_DEBUG", &enableDebug)
	if enableDebug == 1 {
		log.L.Logger.SetLevel(logrus.TraceLevel)
	}

	address := "/run/containerd/containerd.sock"
	if newAddress := os.Getenv("CONTAINERD_ADDRESS"); newAddress != "" {
		address = newAddress
	}
	client, err := containerd.New(address)
	if err != nil {
		log.G(ctx).WithError(err).Fatal("Failed to connect to containerd")
	}
	defer client.Close()

	ongoing := newJobs(ref)
	pctx, stopProgress := context.WithCancel(ctx)
	progress := make(chan struct{})
	go func() {
		showProgress(pctx, ongoing, client.ContentStore(), os.Stdout)
		close(progress)
	}()

	h := images.HandlerFunc(func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
		if desc.MediaType != images.MediaTypeDockerSchema1Manifest {
			ongoing.add(desc)
		}
		return nil, nil
	})

	resolver, err := ecr.NewResolver(ecr.WithLayerDownloadParallelism(parallelism))
	if err != nil {
		log.G(ctx).WithError(err).Fatal("Failed to create resolver")
	}

	log.G(ctx).WithField("ref", ref).Info("Pulling from Amazon ECR")
	img, err := client.Pull(ctx, ref,
		containerd.WithResolver(resolver),
		containerd.WithImageHandler(h),
		containerd.WithSchema1Conversion)
	stopProgress()
	if err != nil {
		log.G(ctx).WithError(err).WithField("ref", ref).Fatal("Failed to pull")
	}
	<-progress
	log.G(ctx).WithField("img", img.Name()).Info("Pulled successfully!")
	if skipUnpack := os.Getenv("ECR_SKIP_UNPACK"); skipUnpack != "" {
		return
	}
	snapshotter := containerd.DefaultSnapshotter
	if newSnapshotter := os.Getenv("CONTAINERD_SNAPSHOTTER"); newSnapshotter != "" {
		snapshotter = newSnapshotter
	}
	log.G(ctx).
		WithField("img", img.Name()).
		WithField("snapshotter", snapshotter).
		Info("unpacking...")
	err = img.Unpack(ctx, snapshotter)
	if err != nil {
		log.G(ctx).WithError(err).WithField("img", img.Name).Fatal("Failed to unpack")
	}
}