feat(nestjs): Derive SentryCron monitor config from @Cron

dev-packages/e2e-tests/test-applications/nestjs-basic/src/app.controller.ts

@@ -86,6 +86,12 @@ export class AppController {
     return { result: await this.appService.testSpanDecoratorSync() };
   }
 
+  @Get('test-derived-cron')
+  async testDerivedCron() {
+    await this.appService.testDerivedCron();
+    return {};
+  }
+
   @Get('kill-test-cron/:job')
   async killTestCron(@Param('job') job: string) {
     this.appService.killTestCron(job);

dev-packages/e2e-tests/test-applications/nestjs-basic/src/app.service.ts

@@ -113,6 +113,13 @@ export class AppService {
     throw new Error('Test error from cron sync job');
   }
 
+  // Disabled so it only runs through the `test-derived-cron` endpoint, without waiting for the schedule.
+  @Cron('0 30 9 * * 1-5', { name: 'test-derived-cron', timeZone: 'Europe/Vienna', disabled: true })
+  @SentryCron('test-derived-cron-slug', { checkinMargin: 2 })
+  async testDerivedCron() {
+    console.log('Test derived cron!');
+  }
+
   async killTestCron(job: string) {
     this.schedulerRegistry.deleteCronJob(job);
   }

dev-packages/e2e-tests/test-applications/nestjs-basic/tests/cron-decorator.test.ts

@@ -62,6 +62,35 @@ test('Cron job triggers send of in_progress envelope', async ({ baseURL }) => {
   await fetch(`${baseURL}/kill-test-cron/test-cron-job`);
 });
 
+test('Sends the schedule and time zone of @Cron with the check-in', async ({ baseURL }) => {
+  const inProgressEnvelopePromise = waitForEnvelopeItem('nestjs-basic', envelope => {
+    return (
+      envelope[0].type === 'check_in' &&
+      envelope[1]['monitor_slug'] === 'test-derived-cron-slug' &&
+      envelope[1]['status'] === 'in_progress'
+    );
+  });
+
+  await fetch(`${baseURL}/test-derived-cron`);
+
+  const inProgressEnvelope = await inProgressEnvelopePromise;
+
+  expect(inProgressEnvelope[1]).toEqual(
+    expect.objectContaining({
+      monitor_slug: 'test-derived-cron-slug',
+      status: 'in_progress',
+      monitor_config: {
+        schedule: {
+          type: 'crontab',
+          value: '30 9 * * 1-5',
+        },
+        timezone: 'Europe/Vienna',
+        checkin_margin: 2,
+      },
+    }),
+  );
+});
+
 test('Sends exceptions to Sentry on error in async cron job', async ({ baseURL }) => {
   const errorEventPromise = waitForError('nestjs-basic', event => {
     return (

packages/nestjs/src/decorators.ts

@@ -1,34 +1,213 @@
 import type { MonitorConfig } from '@sentry/core';
 import { CODE_FUNCTION_NAME } from '@sentry/conventions/attributes';
-import { captureException, SEMANTIC_ATTRIBUTE_SENTRY_OP, SEMANTIC_ATTRIBUTE_SENTRY_ORIGIN } from '@sentry/core';
+import { captureException, debug, SEMANTIC_ATTRIBUTE_SENTRY_OP, SEMANTIC_ATTRIBUTE_SENTRY_ORIGIN } from '@sentry/core';
 import * as Sentry from '@sentry/node';
 import { startSpan } from '@sentry/node';
+import { DEBUG_BUILD } from './debug-build';
 import { isExpectedError } from './helpers';
+import type { ReflectWithMetadata } from './integrations/helpers';
 import { copyReflectMetadata } from './integrations/helpers';
 
+/**
+ * Monitor settings for `@SentryCron` whose schedule and time zone come from the `@Cron()` decorator
+ * of `@nestjs/schedule` on the same method. Set `fromCronDecorator: false` to not send them.
+ */
+export type SentryCronMonitorSettings = Omit<MonitorConfig, 'schedule' | 'timezone'> & {
+  schedule?: never;
+  timezone?: never;
+  fromCronDecorator?: boolean;
+};
+
 /**
  * A decorator wrapping the native nest Cron decorator, sending check-ins to Sentry.
+ *
+ * Unless a monitor config with a `schedule` is passed, the schedule and time zone of the method's
+ * `@Cron()` decorator are sent with each check-in, so Sentry can create the monitor on the first run.
  */
-export const SentryCron = (monitorSlug: string, monitorConfig?: MonitorConfig): MethodDecorator => {
+export const SentryCron = (
+  monitorSlug: string,
+  monitorConfig?: (MonitorConfig & { fromCronDecorator?: never }) | SentryCronMonitorSettings,
+): MethodDecorator => {
   return (target: unknown, propertyKey, descriptor: PropertyDescriptor) => {
     const originalMethod = descriptor.value as (...args: unknown[]) => Promise<unknown>;
 
-    descriptor.value = function (...args: unknown[]) {
+    let resolvedMonitorConfig: MonitorConfig | undefined;
+    let resolved = false;
+
+    const wrappedMethod = function (this: unknown, ...args: unknown[]): unknown {
+      if (!resolved) {
+        resolved = true;
+        // `@Cron()` sets its metadata on whatever function is `descriptor.value` when it runs, which is
+        // this function if it is applied after `@SentryCron()`, so it is only readable at call time.
+        resolvedMonitorConfig = resolveMonitorConfig(monitorSlug, monitorConfig, [
+          wrappedMethod,
+          (target as Record<PropertyKey, unknown> | undefined)?.[propertyKey],
+        ]);
+      }
+
       return Sentry.withMonitor(
         monitorSlug,
         () => {
           return originalMethod.apply(this, args);
         },
-        monitorConfig,
+        resolvedMonitorConfig,
       );
     };
 
+    descriptor.value = wrappedMethod;
+
     copyFunctionNameAndMetadata({ originalMethod, descriptor });
 
     return descriptor;
   };
 };
 
+function resolveMonitorConfig(
+  monitorSlug: string,
+  monitorConfig: MonitorConfig | SentryCronMonitorSettings | undefined,
+  candidates: unknown[],
+): MonitorConfig | undefined {
+  if (monitorConfig?.schedule) {
+    return monitorConfig;
+  }
+
+  const { fromCronDecorator = true, ...monitorSettings } = monitorConfig || {};
+  const cronConfig = fromCronDecorator ? getMonitorConfigFromNestCron(candidates) : undefined;
+
+  if (!cronConfig) {
+    if (DEBUG_BUILD && Object.keys(monitorSettings).length) {
+      const reason = fromCronDecorator
+        ? 'no schedule could be taken from @Cron()'
+        : 'fromCronDecorator is false and no schedule was passed';
+      debug.warn(
+        `[SentryCron] The monitor settings for "${monitorSlug}" are not sent, because ${reason}. A monitor config needs a schedule.`,
+      );
+    }
+    return undefined;
+  }
+
+  return { ...monitorSettings, ...cronConfig };
+}
+
+const SCHEDULE_CRON_OPTIONS = 'SCHEDULE_CRON_OPTIONS';
+
+// Presets of the `cron` package (which also lowercases them), as sent to Sentry. Sentry accepts
+// `@yearly`/`@annually`/`@monthly`/`@weekly`/`@daily`/`@hourly`; the others are sent as crontabs.
+const CRON_PRESETS: Record<string, string | undefined> = {
+  '@yearly': '@yearly',
+  '@annually': '@annually',
+  '@monthly': '@monthly',
+  '@weekly': '@weekly',
+  '@daily': '@daily',
+  '@hourly': '@hourly',
+  '@midnight': '0 0 * * *',
+  '@minutely': '* * * * *',
+  '@weekdays': '0 0 * * 1-5',
+  '@weekends': '0 0 * * 0,6',
+};
+
+interface NestCronOptions {
+  cronTime?: unknown;
+  timeZone?: unknown;
+  utcOffset?: unknown;
+}
+
+function getMonitorConfigFromNestCron(candidates: unknown[]): MonitorConfig | undefined {
+  const R = Reflect as ReflectWithMetadata;
+  if (typeof R.getMetadata !== 'function') {
+    return undefined;
+  }
+
+  for (const candidate of candidates) {
+    if (typeof candidate !== 'function') {
+      continue;
+    }
+    const cronOptions = R.getMetadata(SCHEDULE_CRON_OPTIONS, candidate);
+    if (cronOptions && typeof cronOptions === 'object') {
+      return nestCronOptionsToMonitorConfig(cronOptions);
+    }
+  }
+
+  return undefined;
+}
+
+/**
+ * Converts the options `@Cron()` stores as metadata into a Sentry monitor config.
+ * Returns `undefined` for schedules Sentry can't represent.
+ */
+function nestCronOptionsToMonitorConfig(cronOptions: NestCronOptions): MonitorConfig | undefined {
+  const { cronTime, timeZone, utcOffset } = cronOptions;
+
+  // A fixed UTC offset has no IANA time zone equivalent.
+  if (typeof cronTime !== 'string' || utcOffset != null) {
+    return undefined;
+  }
+
+  const fields = cronTime.trim().split(/\s+/);
+  let crontab: string | undefined;
+  if (fields.length === 1) {
+    crontab = CRON_PRESETS[(fields[0] as string).toLowerCase()];
+  } else if (fields.length === 5) {
+    crontab = isSupportedCrontab(fields) ? fields.join(' ') : undefined;
+  } else if (fields.length === 6 && /^\d+$/.test(fields[0] as string)) {
+    // Sentry schedules have minute granularity, so only a fixed second can be dropped.
+    crontab = isSupportedCrontab(fields.slice(1)) ? fields.slice(1).join(' ') : undefined;
+  }
+
+  if (!crontab) {
+    return undefined;
+  }
+
+  // Without a `timeZone`, the job runs in the server's local time zone.
+  const timezone = typeof timeZone === 'string' && timeZone ? timeZone : getLocalTimeZone();
+
+  // Without a time zone Sentry would assume UTC, which may not be when the job runs.
+  if (!timezone || !isSentryTimeZone(timezone)) {
+    return undefined;
+  }
+
+  return {
+    schedule: { type: 'crontab', value: crontab },
+    timezone,
+  };
+}
+
+/**
+ * Whether Sentry reads the 5 crontab fields the same way `cron` (used by `@nestjs/schedule`) runs them.
+ */
+function isSupportedCrontab([, , dayOfMonth, month, dayOfWeek]: string[]): boolean {
+  // `cron` 2.x (`@nestjs/schedule` 3) counts months from 0, so a numeric month is ambiguous.
+  if (/\d/.test(month as string)) {
+    return false;
+  }
+
+  // With both day fields set, `cron` runs on either, but Sentry needs both when one starts with `*` (like `*/2`).
+  return !(dayOfMonth !== '*' && dayOfWeek !== '*' && (dayOfMonth?.startsWith('*') || dayOfWeek?.startsWith('*')));
+}
+
+/**
+ * Whether Sentry accepts the time zone: an IANA name, not a fixed offset like `UTC+3`.
+ */
+function isSentryTimeZone(timezone: string): boolean {
+  if (timezone === 'Etc/Unknown' || /^(?:utc|gmt)?[+-]/i.test(timezone)) {
+    return false;
+  }
+  try {
+    new Intl.DateTimeFormat('en-US', { timeZone: timezone });
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+function getLocalTimeZone(): string | undefined {
+  try {
+    return Intl.DateTimeFormat().resolvedOptions().timeZone || undefined;
+  } catch {
+    return undefined;
+  }
+}
+
 /**
  * A decorator usable to wrap arbitrary functions with spans.
  */

packages/nestjs/src/index.ts

@@ -8,3 +8,4 @@ export { nestIntegration } from './integrations/nest';
 export { getDefaultIntegrations, init } from './sdk';
 
 export { SentryCron, SentryExceptionCaptured, SentryTraced } from './decorators';
+export type { SentryCronMonitorSettings } from './decorators';