Catalog for V2 API Implementation

This change adds a basic catalog endpoint to the API, which returns a list,
or partial list, of all of the repositories contained in the registry.  Calls
to this endpoint are somewhat expensive, as every call requires walking a
large part of the registry.

Instead, to maintain a list of repositories, you would first call the catalog
endpoint to get an initial list, and then use the events API to maintain
any future repositories.

Signed-off-by: Patrick Devine <patrick.devine@docker.com>

docs/handlers/app.go

@@ -69,6 +69,7 @@ func NewApp(ctx context.Context, configuration configuration.Configuration) *App
 		return http.HandlerFunc(apiBase)
 	})
 	app.register(v2.RouteNameManifest, imageManifestDispatcher)
+	app.register(v2.RouteNameCatalog, catalogDispatcher)
 	app.register(v2.RouteNameTags, tagsDispatcher)
 	app.register(v2.RouteNameBlob, blobDispatcher)
 	app.register(v2.RouteNameBlobUpload, blobUploadDispatcher)
@@ -366,6 +367,9 @@ func (app *App) dispatcher(dispatch dispatchFunc) http.Handler {
 		// Add username to request logging
 		context.Context = ctxu.WithLogger(context.Context, ctxu.GetLogger(context.Context, "auth.user.name"))
 
+		catalog := app.registry.Catalog(context)
+		context.Catalog = catalog
+
 		if app.nameRequired(r) {
 			repository, err := app.registry.Repository(context, getName(context))
 
@@ -493,6 +497,7 @@ func (app *App) authorized(w http.ResponseWriter, r *http.Request, context *Cont
 			}
 			return fmt.Errorf("forbidden: no repository name")
 		}
+		accessRecords = appendCatalogAccessRecord(accessRecords, r)
 	}
 
 	ctx, err := app.accessController.Authorized(context.Context, accessRecords...)
@@ -538,7 +543,8 @@ func (app *App) eventBridge(ctx *Context, r *http.Request) notifications.Listene
 // nameRequired returns true if the route requires a name.
 func (app *App) nameRequired(r *http.Request) bool {
 	route := mux.CurrentRoute(r)
-	return route == nil || route.GetName() != v2.RouteNameBase
+	routeName := route.GetName()
+	return route == nil || (routeName != v2.RouteNameBase && routeName != v2.RouteNameCatalog)
 }
 
 // apiBase implements a simple yes-man for doing overall checks against the
@@ -588,6 +594,26 @@ func appendAccessRecords(records []auth.Access, method string, repo string) []au
 	return records
 }
 
+// Add the access record for the catalog if it's our current route
+func appendCatalogAccessRecord(accessRecords []auth.Access, r *http.Request) []auth.Access {
+	route := mux.CurrentRoute(r)
+	routeName := route.GetName()
+
+	if routeName == v2.RouteNameCatalog {
+		resource := auth.Resource{
+			Type: "registry",
+			Name: "catalog",
+		}
+
+		accessRecords = append(accessRecords,
+			auth.Access{
+				Resource: resource,
+				Action:   "*",
+			})
+	}
+	return accessRecords
+}
+
 // applyRegistryMiddleware wraps a registry instance with the configured middlewares
 func applyRegistryMiddleware(registry distribution.Namespace, middlewares []configuration.Middleware) (distribution.Namespace, error) {
 	for _, mw := range middlewares {