Support rrule for task scheduling

x-pack/platform/plugins/shared/alerting/server/lib/next_run.ts

@@ -13,8 +13,11 @@ export const getNextRun = ({
   interval,
 }: {
   startDate?: Date | null;
-  interval: string;
+  interval?: string;
 }) => {
+  if (!interval) {
+    throw new Error('Interval is required to calculate next run');
+  }
   return moment(startDate || new Date())
     .add(parseDuration(interval), 'ms')
     .toISOString();

x-pack/platform/plugins/shared/alerting/server/task_runner/task_runner.test.ts

@@ -344,6 +344,33 @@ describe('Task Runner', () => {
     ).toHaveBeenCalled();
   });
 
+  test('throws error when schedule.interval is not provided', async () => {
+    mockGetAlertFromRaw.mockReturnValue({ ...mockedRuleTypeSavedObject, schedule: {} } as Rule);
+    encryptedSavedObjectsClient.getDecryptedAsInternalUser.mockResolvedValue({
+      ...mockedRawRuleSO,
+      attributes: { ...mockedRawRuleSO.attributes, schedule: {} },
+    });
+    const taskRunner = new TaskRunner({
+      ruleType,
+      taskInstance: {
+        ...mockedTaskInstance,
+        state: {
+          ...mockedTaskInstance.state,
+          previousStartedAt: new Date(Date.now() - 5 * 60 * 1000).toISOString(),
+        },
+        // @ts-ignore
+        schedule: {},
+      },
+      context: taskRunnerFactoryInitializerParams,
+      inMemoryMetrics,
+      internalSavedObjectsRepository,
+    });
+
+    await expect(taskRunner.run()).rejects.toThrowErrorMatchingInlineSnapshot(
+      '"Interval is required to calculate next run"'
+    );
+  });
+
   test('actionsPlugin.execute is called per alert alert that is scheduled', async () => {
     taskRunnerFactoryInitializerParams.actionsPlugin.isActionTypeEnabled.mockReturnValue(true);
     taskRunnerFactoryInitializerParams.actionsPlugin.isActionExecutable.mockReturnValue(true);

x-pack/platform/plugins/shared/alerting/server/task_runner/task_runner.ts

@@ -593,6 +593,7 @@ export class TaskRunner<
         if (isOk(schedule)) {
           nextRun = getNextRun({ startDate: startedAt, interval: schedule.value.interval });
         } else if (taskSchedule) {
+          // rules cannot use rrule for scheduling yet
           nextRun = getNextRun({ startDate: startedAt, interval: taskSchedule.interval });
         }
 
@@ -828,6 +829,7 @@ export class TaskRunner<
 
     let nextRun: string | null = null;
     if (taskSchedule) {
+      // rules cannot use rrule for scheduling yet
       nextRun = getNextRun({ startDate: startedAt, interval: taskSchedule.interval });
     }