[coordinator] Add support for Graphite Grafana plugin /find POST requ…

…ests (#2153)

src/query/api/v1/handler/graphite/find_parser.go

@@ -57,8 +57,7 @@ func parseFindParamsToQueries(r *http.Request) (
 	_rawQueryString string,
 	_err *xhttp.ParseError,
 ) {
-	values := r.URL.Query()
-	query := values.Get("query")
+	query := r.FormValue("query")
 	if query == "" {
 		return nil, nil, "",
 			xhttp.NewParseError(errors.ErrNoQueryFound, http.StatusBadRequest)

src/query/api/v1/handler/graphite/find_test.go

@@ -218,7 +218,7 @@ func (r results) Less(i, j int) bool {
 	return strings.Compare(r[i].ID, r[j].ID) == -1
 }
 
-func testFind(t *testing.T, ex bool, ex2 bool, header string) {
+func testFind(t *testing.T, httpMethod string, ex bool, ex2 bool, header string) {
 	ctrl := gomock.NewController(t)
 	defer ctrl.Finish()
 
@@ -233,11 +233,22 @@ func testFind(t *testing.T, ex bool, ex2 bool, header string) {
 	h := NewFindHandler(opts)
 
 	// execute the query
+	params := make(url.Values)
+	params.Set("query", "foo.b*")
+	params.Set("from", from.s)
+	params.Set("until", until.s)
+
 	w := &writer{}
 	req := &http.Request{
-		URL: &url.URL{
-			RawQuery: fmt.Sprintf("query=foo.b*&from=%s&until=%s", from.s, until.s),
-		},
+		Method: httpMethod,
+	}
+	switch httpMethod {
+	case http.MethodGet:
+		req.URL = &url.URL{
+			RawQuery: params.Encode(),
+		}
+	case http.MethodPost:
+		req.Form = params
 	}
 
 	h.ServeHTTP(w, req)
@@ -289,7 +300,9 @@ var limitTests = []struct {
 func TestFind(t *testing.T) {
 	for _, tt := range limitTests {
 		t.Run(tt.name, func(t *testing.T) {
-			testFind(t, tt.ex, tt.ex2, tt.header)
+			for _, httpMethod := range FindHTTPMethods {
+				testFind(t, httpMethod, tt.ex, tt.ex2, tt.header)
+			}
 		})
 	}
 }

src/query/api/v1/handler/prometheus/handleroptions/fetch_options.go

@@ -81,7 +81,7 @@ func ParseLimit(req *http.Request, defaultLimit int) (int, error) {
 		return n, nil
 	}
 
-	if str := req.URL.Query().Get("limit"); str != "" {
+	if str := req.FormValue("limit"); str != "" {
 		n, err := strconv.Atoi(str)
 		if err != nil {
 			err = fmt.Errorf(