🔧 Extract common func into api function, also set sane defaults

pkg/api/core/image/digest.go

@@ -0,0 +1,42 @@
+// Copyright © 2021 Ettore Di Giacinto <mudler@mocaccino.org>
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 2 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this program; if not, see <http://www.gnu.org/licenses/>.
+
+package image
+
+import (
+	"crypto/tls"
+	"net/http"
+
+	"github.com/google/go-containerregistry/pkg/crane"
+	"github.com/google/go-containerregistry/pkg/v1/remote"
+)
+
+// Available checks if the image is available in the remote endpoint.
+func Available(image string, opt ...crane.Option) bool {
+	// We use crane.insecure as we just check if the image is available
+	// It's the daemon duty to use it or not based on the host settings
+	transport := remote.DefaultTransport.Clone()
+	transport.TLSClientConfig = &tls.Config{
+		InsecureSkipVerify: true, //nolint: gosec
+	}
+
+	var rt http.RoundTripper = transport
+	if len(opt) == 0 {
+		opt = append(opt, crane.Insecure, crane.WithTransport(rt))
+	}
+
+	_, err := crane.Digest(image, opt...)
+	return err == nil
+}