Use correct unmarshaller for json durations

api/types/duration.go

@@ -57,7 +57,7 @@ func (d *Duration) UnmarshalJSON(data []byte) error {
 		*d = Duration(0)
 		return nil
 	}
-	out, err := time.ParseDuration(stringVar)
+	out, err := parseDuration(stringVar)
 	if err != nil {
 		return trace.BadParameter(err.Error())
 	}

api/types/duration_test.go

@@ -0,0 +1,62 @@
+/*
+Copyright 2022 Gravitational, Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package types
+
+import (
+	"testing"
+	"time"
+)
+
+type testCase struct {
+	name          string
+	stringValue   string
+	expectedValue Duration
+}
+
+// TestDurationUnmarshal tests unmarshaling of various duration formats.
+func TestDurationUnmarshal(t *testing.T) {
+	testCases := []testCase{
+		{
+			name:          "simple",
+			stringValue:   `"100h"`,
+			expectedValue: Duration(time.Hour * 100),
+		},
+		{
+			name:          "combined large",
+			stringValue:   `"1y6mo"`,
+			expectedValue: Duration(time.Hour*24*365 + time.Hour*24*30*6),
+		},
+		{
+			name:          "large + small",
+			stringValue:   `"24d30μs"`,
+			expectedValue: Duration(time.Hour*24*24 + time.Microsecond*30),
+		},
+	}
+
+	for _, testCase := range testCases {
+		t.Run(testCase.name, func(t *testing.T) {
+			var duration Duration
+			err := duration.UnmarshalJSON([]byte(testCase.stringValue))
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+			if duration != testCase.expectedValue {
+				t.Fatalf("unexpected value: %v", duration)
+			}
+		})
+	}
+}