POC for WithMirror transport

pkg/v1/remote/options.go

@@ -54,6 +54,8 @@ type options struct {
 	// Set by Reuse, we currently store one or the other.
 	puller *Puller
 	pusher *Pusher
+
+	mirrors []transport.Mirror
 }
 
 var defaultPlatform = v1.Platform{
@@ -100,6 +102,8 @@ var defaultRetryStatusCodes = []int{
 	522, // Cloudflare-specific, connection timeout
 }
 
+var defaultMirrors = []transport.Mirror{}
+
 const (
 	defaultJobs = 4
 
@@ -135,6 +139,7 @@ func makeOptions(opts ...Option) (*options, error) {
 		retryPredicate:   defaultRetryPredicate,
 		retryBackoff:     defaultRetryBackoff,
 		retryStatusCodes: defaultRetryStatusCodes,
+		mirrors:          defaultMirrors,
 	}
 
 	for _, option := range opts {
@@ -169,6 +174,16 @@ func makeOptions(opts ...Option) (*options, error) {
 		if o.userAgent != "" {
 			o.transport = transport.NewUserAgent(o.transport, o.userAgent)
 		}
+
+		if len(o.mirrors) > 0 {
+			o.transport = transport.NewWithMirrors(o.transport, o.mirrors)
+		} else {
+			testMirror := transport.Mirror{
+				OriginUrl:       "docker://quay.io/ubi9",
+				MirrorEndpoints: []transport.MirrorEndpoint{{Secure: false, Endpoint: "docker://localhost:5000/ubi9"}},
+			}
+			o.transport = transport.NewWithMirrors(o.transport, []transport.Mirror{testMirror})
+		}
 	}
 
 	return o, nil
@@ -331,6 +346,16 @@ func WithFilter(key string, value string) Option {
 	}
 }
 
+func WithMirrors(m ...transport.Mirror) Option {
+	return func(o *options) error {
+		if o.mirrors == nil {
+			o.mirrors = make([]transport.Mirror, 0)
+		}
+		o.mirrors = append(o.mirrors, m...)
+		return nil
+	}
+}
+
 // Reuse takes a Puller or Pusher and reuses it for remote interactions
 // rather than starting from a clean slate. For example, it will reuse token exchanges
 // when possible and avoid sending redundant HEAD requests.

pkg/v1/remote/transport/mirror.go

@@ -0,0 +1,96 @@
+package transport
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+)
+
+type Mirror struct {
+	OriginUrl       string
+	MirrorEndpoints []MirrorEndpoint
+}
+
+type MirrorEndpoint struct {
+	Endpoint string
+	Secure   bool
+}
+type mirrorTransport struct {
+	inner   http.RoundTripper
+	mirrors []Mirror
+}
+
+var _ http.RoundTripper = (*mirrorTransport)(nil)
+
+func NewWithMirrors(inner http.RoundTripper, mirrors []Mirror) http.RoundTripper {
+	return &mirrorTransport{
+		inner:   inner,
+		mirrors: mirrors,
+	}
+}
+
+func (t *mirrorTransport) RoundTrip(in *http.Request) (out *http.Response, err error) {
+	if len(t.mirrors) > 0 {
+		for _, mirror := range t.mirrors {
+			if isApplicable, err := mirror.isApplicableTo(*in.URL); isApplicable && err == nil {
+				for _, endpoint := range mirror.MirrorEndpoints {
+					mirroredRequest, err := mirror.useMirrorEndpoint(in, endpoint)
+					if err != nil {
+						fmt.Printf("ERROR: Request %v: %v\n", mirroredRequest, err)
+						continue
+					}
+					out, err = t.inner.RoundTrip(mirroredRequest)
+					if err != nil {
+						fmt.Printf("ERROR: Request %v: %v\n", mirroredRequest, err)
+						continue
+					}
+					return out, err
+				}
+			}
+		}
+	}
+	return t.inner.RoundTrip(in)
+}
+
+func (m Mirror) isApplicableTo(url url.URL) (bool, error) {
+	mirrorUrl, err := url.Parse(m.OriginUrl)
+	if err != nil {
+		return false, fmt.Errorf("unable to parse mirror origin url %s: %v", m.OriginUrl, err)
+	}
+	if strings.Contains(url.Host, mirrorUrl.Host) || strings.Contains(url.Path, mirrorUrl.Path) {
+		fmt.Printf("INFO: Request %v: mirror %v matches\n", url, m)
+		return true, nil
+	}
+	return false, nil
+}
+
+func (m Mirror) useMirrorEndpoint(in *http.Request, mirrorEndpoint MirrorEndpoint) (*http.Request, error) {
+	mirrorUrl, err := url.Parse(m.OriginUrl)
+	if err != nil {
+		return in, fmt.Errorf("unable to parse mirror origin url %s: %v", m.OriginUrl, err)
+	}
+	mirrorEndpointUrl, err := url.Parse(mirrorEndpoint.Endpoint)
+	if err != nil {
+		return in, fmt.Errorf("unable to parse mirror endpoint %s: %v", mirrorEndpoint.Endpoint, err)
+	}
+
+	mirroredIn := in.Clone(in.Context())
+	inURL := in.URL.String()
+	inURL = strings.Replace(inURL, mirrorUrl.Host, mirrorEndpointUrl.Host, 1)
+	inURL = strings.Replace(inURL, mirrorUrl.Path, mirrorEndpointUrl.Path, 1)
+	if in.URL.Scheme == "https" && !mirrorEndpoint.Secure {
+		inURL = strings.Replace(inURL, "https", "http", 1)
+	}
+	if in.URL.Scheme == "http" && mirrorEndpoint.Secure {
+		inURL = strings.Replace(inURL, "http", "https", 1)
+	}
+	mirroredRequestURL, err := url.Parse(inURL)
+	if err != nil {
+		return in, fmt.Errorf("unable to parse mirror endpoint %s: %v", mirrorEndpoint.Endpoint, err)
+
+	}
+	mirroredIn.URL = mirroredRequestURL
+	fmt.Printf("using %v as mirror of %v\n", mirroredIn.URL.String(), in.URL.String())
+	return mirroredIn, nil
+}