Configuration

All configuration is done in code when calling createMonitor(). There are no config files.

MonitorConfig options

Option	Type	Default	Description
`slowQueryThresholdMs`	`number`	`200`	Threshold in ms for slow query detection
`exporter`	`Exporter`	`—`	Required. Receives all emitted events
`emitPositiveSignals`	`boolean`	`false`	Enable INFO-level healthy signals
`includeDocs`	`boolean`	`true`	Include signal explanations in events

Full example

typescript

import { createMonitor, SignalSeverity } from '@periodic/arsenic';

const monitor = createMonitor({
  // Slow query threshold — queries over this emit slow_query signal
  slowQueryThresholdMs: 200,

  // Required — your event router
  exporter: (event) => {
    switch (event.severity) {
      case SignalSeverity.CRITICAL: sendToPagerDuty(event); break;
      case SignalSeverity.WARNING:  sendToSlack(event);     break;
      case SignalSeverity.INFO:     logger.info(event);     break;
    }
  },

  // Enable INFO signals (disabled by default to reduce noise)
  emitPositiveSignals: false,

  // Include human-readable signal explanations in events
  includeDocs: true,
});

Framework adapter options

typescript

// Express context
app.use(expressContext(monitor, {
  // Optional — extract user ID from request for event attribution
  attachUser: (req) => req.user?.id,
}));

// Fastify context
app.register(fastifyContext(monitor, {
  attachUser: (req) => req.user?.id,
}));

Environment-based configuration

src/config/monitor.ts

typescript

const isDev = process.env.NODE_ENV === 'development';

const monitor = createMonitor({
  // Looser in dev, stricter in prod
  slowQueryThresholdMs: isDev ? 500 : 200,

  // More verbose in dev
  emitPositiveSignals: isDev,
  includeDocs: isDev,

  exporter: async (event) => {
    // Always log
    logger.info(event, 'db.event');

    // Only alert in production
    if (!isDev && event.severity === SignalSeverity.CRITICAL) {
      await sendToPagerDuty(event);
    }
  },
});

export default monitor;

No global state

Each monitor is a fully independent instance. Create multiple monitors with different thresholds for different databases or services. Safe for multi-tenant applications.