@saas-pro-lib/monitoring

Shared monitoring helpers for SaaS frontends.

The package keeps provider SDKs optional. Product apps can use the Sentry sampler without importing @sentry/nextjs, and can pass the AwsRum constructor only in browser-only initialization code.

Sentry trace sampling

import {
  buildSentryTracesSamplerFromEnv,
  DEFAULT_TRACE_SAMPLING_POLICY,
} from "@saas-pro-lib/monitoring";

Sentry.init({
  dsn,
  environment,
  tracesSampler: buildSentryTracesSamplerFromEnv(
    process.env.NEXT_PUBLIC_SENTRY_TRACES_SAMPLE_RATE,
    DEFAULT_TRACE_SAMPLING_POLICY,
  ),
});

Default priority:

1. Health-like server paths: 0%
2. Error or 5xx: 100%
3. Billing / Stripe paths: 100%
4. Auth / OAuth paths: 50%
5. Sequence execution paths and sequence-step-executor: 30%
6. CRM core paths: 15%
7. Admin paths: 50%
8. Baseline: 10%, clipped at 30%

Products can provide a custom TraceSamplingPolicy to replace the path priorities while keeping the same resolver.

CloudWatch RUM

import { AwsRum } from "aws-rum-web";
import { createCloudWatchRumMonitor } from "@saas-pro-lib/monitoring";

const rum = createCloudWatchRumMonitor(
  {
    applicationId: process.env.NEXT_PUBLIC_AWS_RUM_APPLICATION_ID,
    identityPoolId: process.env.NEXT_PUBLIC_AWS_RUM_IDENTITY_POOL_ID,
    applicationVersion: "1.0.0",
    applicationRegion: "ap-northeast-1",
  },
  AwsRum,
);

rum.recordError(new Error("example"));

When required IDs are missing, initialization returns an explicit disabled monitor instead of throwing or silently pretending to send data.