Move registry package into handler package

The goal is to free up the distribution/registry package to include common
registry types. This moves the webapp definitions out of the way to allow for
this change in the future.

Signed-off-by: Stephen J Day <stephen.day@docker.com>

docs/handlers/images.go

@@ -0,0 +1,118 @@
+package handlers
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+
+	"github.com/docker/distribution/api/v2"
+	ctxu "github.com/docker/distribution/context"
+	"github.com/docker/distribution/digest"
+	"github.com/docker/distribution/manifest"
+	"github.com/docker/distribution/storage"
+	"github.com/gorilla/handlers"
+)
+
+// imageManifestDispatcher takes the request context and builds the
+// appropriate handler for handling image manifest requests.
+func imageManifestDispatcher(ctx *Context, r *http.Request) http.Handler {
+	imageManifestHandler := &imageManifestHandler{
+		Context: ctx,
+		Tag:     getTag(ctx),
+	}
+
+	return handlers.MethodHandler{
+		"GET":    http.HandlerFunc(imageManifestHandler.GetImageManifest),
+		"PUT":    http.HandlerFunc(imageManifestHandler.PutImageManifest),
+		"DELETE": http.HandlerFunc(imageManifestHandler.DeleteImageManifest),
+	}
+}
+
+// imageManifestHandler handles http operations on image manifests.
+type imageManifestHandler struct {
+	*Context
+
+	Tag string
+}
+
+// GetImageManifest fetches the image manifest from the storage backend, if it exists.
+func (imh *imageManifestHandler) GetImageManifest(w http.ResponseWriter, r *http.Request) {
+	ctxu.GetLogger(imh).Debug("GetImageManifest")
+	manifests := imh.Repository.Manifests()
+	manifest, err := manifests.Get(imh.Tag)
+
+	if err != nil {
+		imh.Errors.Push(v2.ErrorCodeManifestUnknown, err)
+		w.WriteHeader(http.StatusNotFound)
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.Header().Set("Content-Length", fmt.Sprint(len(manifest.Raw)))
+	w.Write(manifest.Raw)
+}
+
+// PutImageManifest validates and stores and image in the registry.
+func (imh *imageManifestHandler) PutImageManifest(w http.ResponseWriter, r *http.Request) {
+	ctxu.GetLogger(imh).Debug("PutImageManifest")
+	manifests := imh.Repository.Manifests()
+	dec := json.NewDecoder(r.Body)
+
+	var manifest manifest.SignedManifest
+	if err := dec.Decode(&manifest); err != nil {
+		imh.Errors.Push(v2.ErrorCodeManifestInvalid, err)
+		w.WriteHeader(http.StatusBadRequest)
+		return
+	}
+
+	if err := manifests.Put(imh.Tag, &manifest); err != nil {
+		// TODO(stevvooe): These error handling switches really need to be
+		// handled by an app global mapper.
+		switch err := err.(type) {
+		case storage.ErrManifestVerification:
+			for _, verificationError := range err {
+				switch verificationError := verificationError.(type) {
+				case storage.ErrUnknownLayer:
+					imh.Errors.Push(v2.ErrorCodeBlobUnknown, verificationError.FSLayer)
+				case storage.ErrManifestUnverified:
+					imh.Errors.Push(v2.ErrorCodeManifestUnverified)
+				default:
+					if verificationError == digest.ErrDigestInvalidFormat {
+						// TODO(stevvooe): We need to really need to move all
+						// errors to types. Its much more straightforward.
+						imh.Errors.Push(v2.ErrorCodeDigestInvalid)
+					} else {
+						imh.Errors.PushErr(verificationError)
+					}
+				}
+			}
+		default:
+			imh.Errors.PushErr(err)
+		}
+
+		w.WriteHeader(http.StatusBadRequest)
+		return
+	}
+
+	w.WriteHeader(http.StatusAccepted)
+}
+
+// DeleteImageManifest removes the image with the given tag from the registry.
+func (imh *imageManifestHandler) DeleteImageManifest(w http.ResponseWriter, r *http.Request) {
+	ctxu.GetLogger(imh).Debug("DeleteImageManifest")
+	manifests := imh.Repository.Manifests()
+	if err := manifests.Delete(imh.Tag); err != nil {
+		switch err := err.(type) {
+		case storage.ErrUnknownManifest:
+			imh.Errors.Push(v2.ErrorCodeManifestUnknown, err)
+			w.WriteHeader(http.StatusNotFound)
+		default:
+			imh.Errors.Push(v2.ErrorCodeUnknown, err)
+			w.WriteHeader(http.StatusBadRequest)
+		}
+		return
+	}
+
+	w.Header().Set("Content-Length", "0")
+	w.WriteHeader(http.StatusAccepted)
+}