Set an Allow header in 405 responses.

pkg/rest/handlers.go

@@ -52,6 +52,8 @@ var (
 		http.MethodGet:  struct{}{},
 		http.MethodHead: struct{}{},
 	}
+	allowHealthz = "GET, HEAD"
+
 	allowedPems = map[string]struct{}{
 		http.MethodGet:    struct{}{},
 		http.MethodHead:   struct{}{},
@@ -59,6 +61,7 @@ var (
 		http.MethodPost:   struct{}{},
 		http.MethodPut:    struct{}{},
 	}
+	allowPems = "GET, HEAD, PUT, POST, DELETE"
 )
 
 // Date format for Common Log Format
@@ -100,6 +103,7 @@ func (h *healthzHndlr) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
 		status = http.StatusNotFound
 	} else if _, ok := allowedHealthz[req.Method]; !ok {
 		status = http.StatusMethodNotAllowed
+		resp.Header().Set("Allow", allowHealthz)
 	} else {
 		status = http.StatusNoContent
 		resp.Header().Del("Content-Length")
@@ -147,6 +151,7 @@ func (h *pemsHndlr) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
 
 	if _, ok := allowedPems[req.Method]; !ok {
 		status = http.StatusMethodNotAllowed
+		resp.Header().Set("Allow", allowPems)
 		resp.WriteHeader(status)
 		reqLog(h.log, req, now, status, bytes)
 		return

pkg/rest/handlers_test.go

@@ -122,6 +122,11 @@ func TestHealthz405(t *testing.T) {
 			t.Errorf("%s /v1/healthz status: got %d want %d",
 				method, rr.Code, http.StatusMethodNotAllowed)
 		}
+		if rr.Result().Header.Get("Allow") != allowHealthz {
+			t.Errorf("%s /v1/healthz Allow: got %s want %s",
+				method, rr.Result().Header.Get("Allow"),
+				allowHealthz)
+		}
 		if rr.Result().Header.Get("Content-Length") != "0" {
 			t.Errorf("%s /v1/healthz Content-Length: got %s want 0",
 				method, rr.Result().Header.
@@ -753,6 +758,11 @@ func TestPem405(t *testing.T) {
 			t.Errorf("%s /v1/pems/ns/name status: got %d want %d",
 				method, rr.Code, http.StatusMethodNotAllowed)
 		}
+		if rr.Result().Header.Get("Allow") != allowPems {
+			t.Errorf("%s /v1/pems/ns/name Allow: got %s want %s",
+				method, rr.Result().Header.Get("Allow"),
+				allowPems)
+		}
 		if rr.Result().Header.Get("Content-Length") != "0" {
 			t.Errorf("%s /v1/pems/ns/name Content-Length: "+
 				"got %s want 0", method,