func (p *GCRProvider) Supports(url image.URL) bool {
	return gcrhosts.MatchString(url.Host)
}
Supports returns true if the URLs host is one of the google cloud registry hosts
package provider
import (
	"context"
	"net/http"
	"os"
	"regexp"
	"sync"
	"github.com/seantis/roots/pkg/image"
	"golang.org/x/oauth2/google"
)
type GCRProvider struct {
	clients map[string]*http.Client
	mu      sync.Mutex
}
func init() {
	image.RegisterProvider("gcr", &GCRProvider{
		clients: make(map[string]*http.Client),
	})
}
var gcrhosts = regexp.MustCompile(`([a-z]+?\.)?gcr\.io`)
var gcrscope = "https://www.googleapis.com/auth/devstorage.read_only"