added repocli

pkg/repocli/manexist.go

@@ -0,0 +1,60 @@
+package repocli
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"strconv"
+)
+
+func (cli *Client) ManifestExists(ctx context.Context, rawrepo, tag string) (bool, string, int64, string, error) {
+	var err error
+	var exist bool
+	var mime string
+	var size int64
+	var csum string
+
+	ref, err := NewRepository(rawrepo)
+	if err != nil {
+		return exist, mime, size, csum, err
+	}
+	uri := ref.Manifest(tag)
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodHead, uri, nil)
+	if err != nil {
+		return exist, mime, size, csum, err
+	}
+	req.Header.Set("User-Agent", cli.userAgent)
+	req.Header.Set("Accept", "*/*")
+	resp, err := cli.httpClient.Do(req)
+	if err != nil {
+		return exist, mime, size, csum, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode == http.StatusNotFound {
+		return exist, mime, size, csum, err
+	}
+	if resp.StatusCode != http.StatusOK {
+		err := fmt.Errorf("Unxected response code %s", resp.Status)
+		return exist, mime, size, csum, err
+	}
+	contentLength := resp.Header.Get("Content-Length")
+	size, err = strconv.ParseInt(contentLength, 10, 64)
+	if err != nil {
+		return exist, mime, size, csum, err
+	}
+	mime = resp.Header.Get("Content-Type")
+	if mime == "" {
+		err := fmt.Errorf("Empty MIME type declaration")
+		return exist, mime, size, csum, err
+	}
+	csum = resp.Header.Get("Docker-Content-Digest")
+	if csum == "" {
+		err := fmt.Errorf("Empty digest declaration")
+		return exist, mime, size, csum, err
+	}
+
+	exist = true
+	return exist, mime, size, csum, err
+}