Add imgpkg-session-id to http headers

pkg/imgpkg/registry/registry.go

@@ -7,6 +7,7 @@ import (
 	"crypto/tls"
 	"crypto/x509"
 	"fmt"
+	"math/rand"
 	"net/http"
 	"os"
 	"regexp"
@@ -42,6 +43,8 @@ type Opts struct {
 
 	EnvironFunc     func() []string
 	ActiveKeychains []auth.IAASKeychain
+
+	SessionID string
 }
 
 // DeepCopy the options to a new struct
@@ -194,6 +197,12 @@ func NewSimpleRegistryWithTransport(opts Opts, rTripper http.RoundTripper) (*Sim
 		baseRoundTripper = transport.NewLogger(rTripper)
 	}
 
+	sessionID := opts.SessionID
+	if sessionID == "" {
+		sessionID = fmt.Sprint(rand.Intn(9999999999))
+	}
+	baseRoundTripper = NewImgpkgRoundTripper(baseRoundTripper, sessionID)
+
 	// Wrap the transport in something that can retry network flakes.
 	baseRoundTripper = transport.NewRetry(baseRoundTripper, transport.WithRetryBackoff(retryBackoff))
 

pkg/imgpkg/registry/registry_test.go

@@ -65,6 +65,49 @@ func TestRegistry_Digest(t *testing.T) {
 	})
 }
 
+func TestRegistry_TransportHeaders(t *testing.T) {
+	t.Run("when doing request to registry, imgpkg sends the header imgpkg-session-id", func(t *testing.T) {
+		expectedDigest := "sha256:477c34d98f9e090a4441cf82d2f1f03e64c8eb730e8c1ef39a8595e685d4df65"
+		server := createServer(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Docker-Content-Digest", expectedDigest)
+			require.Equal(t, "673062197574995717", r.Header.Get("imgpkg-session-id"))
+		})
+		defer server.Close()
+		u, err := url.Parse(server.URL)
+		require.NoError(t, err)
+
+		subject, err := registry.NewSimpleRegistry(registry.Opts{SessionID: "673062197574995717"})
+		require.NoError(t, err)
+
+		imgRef, err := name.ParseReference(fmt.Sprintf("%s/repo:latest", u.Host))
+		require.NoError(t, err)
+		_, err = subject.Digest(imgRef)
+		require.NoError(t, err)
+	})
+
+	t.Run("when doing 2 request to registry, the value in the header imgpkg-session-id does not change", func(t *testing.T) {
+		expectedDigest := "sha256:477c34d98f9e090a4441cf82d2f1f03e64c8eb730e8c1ef39a8595e685d4df65"
+		server := createServer(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Docker-Content-Digest", expectedDigest)
+			require.Equal(t, "673062197574995717", r.Header.Get("imgpkg-session-id"))
+		})
+		defer server.Close()
+		u, err := url.Parse(server.URL)
+		require.NoError(t, err)
+
+		subject, err := registry.NewSimpleRegistry(registry.Opts{SessionID: "673062197574995717"})
+		require.NoError(t, err)
+
+		imgRef, err := name.ParseReference(fmt.Sprintf("%s/repo:latest", u.Host))
+		require.NoError(t, err)
+		_, err = subject.Digest(imgRef)
+		require.NoError(t, err)
+
+		_, err = subject.Digest(imgRef)
+		require.NoError(t, err)
+	})
+}
+
 func createServer(handler func(w http.ResponseWriter, r *http.Request)) *httptest.Server {
 	response := []byte("doesn't matter")
 	return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

pkg/imgpkg/registry/transport.go

@@ -169,3 +169,23 @@ func (n NoopRoundTripperStorage) CreateRoundTripper(_ regname.Registry, _ authn.
 func (n NoopRoundTripperStorage) BaseRoundTripper() http.RoundTripper {
 	return nil
 }
+
+// NewImgpkgRoundTripper creates a RoundTripper that will add headers to the request
+func NewImgpkgRoundTripper(parent http.RoundTripper, sessionID string) *ImgpkgRoundTripper {
+	return &ImgpkgRoundTripper{
+		parent:    parent,
+		sessionID: sessionID,
+	}
+}
+
+// ImgpkgRoundTripper RoundTripper that adds headers to request
+type ImgpkgRoundTripper struct {
+	parent    http.RoundTripper
+	sessionID string
+}
+
+// RoundTrip changes the request to add headers and calls the parent RoundTrip
+func (i *ImgpkgRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	req.Header.Add("imgpkg-session-id", i.sessionID)
+	return i.parent.RoundTrip(req)
+}