@@ -12,10 +12,8 @@ import (

 	"github.com/sirupsen/logrus"

 )

-type contextKey string

-

 // APIVersionKey is the client's requested API version.

-const APIVersionKey contextKey = "api-version"

+type APIVersionKey struct{}

 // APIFunc is an adapter to allow the use of ordinary functions as Docker API endpoints.

 // Any function that has the appropriate signature can be registered as an API endpoint (e.g. getVersion).

@@ -83,7 +81,7 @@ func VersionFromContext(ctx context.Context) string {

 		return ""

 	}

-	if val := ctx.Value(APIVersionKey); val != nil {

+	if val := ctx.Value(APIVersionKey{}); val != nil {

 		return val.(string)

 	}

@@ -58,7 +58,7 @@ func (v VersionMiddleware) WrapHandler(handler func(ctx context.Context, w http.

 		if versions.GreaterThan(apiVersion, v.defaultVersion) {

 			return versionUnsupportedError{version: apiVersion, maxVersion: v.defaultVersion}

 		}

-		ctx = context.WithValue(ctx, httputils.APIVersionKey, apiVersion)

+		ctx = context.WithValue(ctx, httputils.APIVersionKey{}, apiVersion)

 		return handler(ctx, w, r, vars)

 	}

@@ -129,8 +129,7 @@ func (s *Server) makeHTTPHandler(handler httputils.APIFunc) http.HandlerFunc {

 		// use intermediate variable to prevent "should not use basic type

 		// string as key in context.WithValue" golint errors

-		var ki interface{} = dockerversion.UAStringKey

-		ctx := context.WithValue(context.Background(), ki, r.Header.Get("User-Agent"))

+		ctx := context.WithValue(context.Background(), dockerversion.UAStringKey{}, r.Header.Get("User-Agent"))

 		handlerFunc := s.handlerWithGlobalMiddlewares(handler)

 		vars := mux.Vars(r)

@@ -10,7 +10,7 @@ import (

 )

 // UAStringKey is used as key type for user-agent string in net/context struct

-const UAStringKey = "upstream-user-agent"

+type UAStringKey struct{}

 // DockerUserAgent is the User-Agent the Docker client uses to identify itself.

 // In accordance with RFC 7231 (5.5.3) is of the form:

@@ -39,9 +39,9 @@ func DockerUserAgent(ctx context.Context) string {

 func getUserAgentFromContext(ctx context.Context) string {

 	var upstreamUA string

 	if ctx != nil {

-		var ki interface{} = ctx.Value(UAStringKey)

+		var ki interface{} = ctx.Value(UAStringKey{})

 		if ki != nil {

-			upstreamUA = ctx.Value(UAStringKey).(string)

+			upstreamUA = ctx.Value(UAStringKey{}).(string)

 		}

 	}

 	return upstreamUA