swarm: fix API version detection

While the docker cli may be sending a "version" header, this header
is not part of the API, or at least should not determin what API
version is used.

This code was added in c0afd9c873183604e57282e1cf47605c1f1e4d43, to
adjust the handling of requests when an older version of the API was
used, but because the code relied on the "version" header set by the
CLI, it didn't work with other clients (e.g. when using cURL to make
an API request).

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

api/server/router/swarm/cluster_routes.go

@@ -225,15 +225,13 @@ func (sr *swarmRouter) createService(ctx context.Context, w http.ResponseWriter,
 
 	// Get returns "" if the header does not exist
 	encodedAuth := r.Header.Get("X-Registry-Auth")
-	cliVersion := r.Header.Get("version")
 	queryRegistry := false
-	if cliVersion != "" {
-		if versions.LessThan(cliVersion, "1.30") {
+	if v := httputils.VersionFromContext(ctx); v != "" {
+		if versions.LessThan(v, "1.30") {
 			queryRegistry = true
 		}
-		adjustForAPIVersion(cliVersion, &service)
+		adjustForAPIVersion(v, &service)
 	}
-
 	resp, err := sr.backend.CreateService(service, encodedAuth, queryRegistry)
 	if err != nil {
 		logrus.Errorf("Error creating service %s: %v", service.Name, err)
@@ -265,13 +263,12 @@ func (sr *swarmRouter) updateService(ctx context.Context, w http.ResponseWriter,
 	flags.EncodedRegistryAuth = r.Header.Get("X-Registry-Auth")
 	flags.RegistryAuthFrom = r.URL.Query().Get("registryAuthFrom")
 	flags.Rollback = r.URL.Query().Get("rollback")
-	cliVersion := r.Header.Get("version")
 	queryRegistry := false
-	if cliVersion != "" {
-		if versions.LessThan(cliVersion, "1.30") {
+	if v := httputils.VersionFromContext(ctx); v != "" {
+		if versions.LessThan(v, "1.30") {
 			queryRegistry = true
 		}
-		adjustForAPIVersion(cliVersion, &service)
+		adjustForAPIVersion(v, &service)
 	}
 
 	resp, err := sr.backend.UpdateService(vars["id"], version, service, flags, queryRegistry)