PostHog Observability

Overview

Set up comprehensive observability for PostHog integrations.

Prerequisites

• Prometheus or compatible metrics backend
• OpenTelemetry SDK installed
• Grafana or similar dashboarding tool
• AlertManager configured

Metrics Collection

Key Metrics

Metric	Type	Description
posthog_requests_total	Counter	Total API requests
posthog_request_duration_seconds	Histogram	Request latency
posthog_errors_total	Counter	Error count by type
posthog_rate_limit_remaining	Gauge	Rate limit headroom

Prometheus Metrics

import { Registry, Counter, Histogram, Gauge } from 'prom-client';

const registry = new Registry();

const requestCounter = new Counter({
  name: 'posthog_requests_total',
  help: 'Total PostHog API requests',
  labelNames: ['method', 'status'],
  registers: [registry],
});

const requestDuration = new Histogram({
  name: 'posthog_request_duration_seconds',
  help: 'PostHog request duration',
  labelNames: ['method'],
  buckets: [0.05, 0.1, 0.25, 0.5, 1, 2.5, 5],
  registers: [registry],
});

const errorCounter = new Counter({
  name: 'posthog_errors_total',
  help: 'PostHog errors by type',
  labelNames: ['error_type'],
  registers: [registry],
});

Instrumented Client

async function instrumentedRequest<T>(
  method: string,
  operation: () => Promise<T>
): Promise<T> {
  const timer = requestDuration.startTimer({ method });

  try {
    const result = await operation();
    requestCounter.inc({ method, status: 'success' });
    return result;
  } catch (error: any) {
    requestCounter.inc({ method, status: 'error' });
    errorCounter.inc({ error_type: error.code || 'unknown' });
    throw error;
  } finally {
    timer();
  }
}

Distributed Tracing

OpenTelemetry Setup

import { trace, SpanStatusCode } from '@opentelemetry/api';

const tracer = trace.getTracer('posthog-client');

async function tracedPostHogCall<T>(
  operationName: string,
  operation: () => Promise<T>
): Promise<T> {
  return tracer.startActiveSpan(`posthog.${operationName}`, async (span) => {
    try {
      const result = await operation();
      span.setStatus({ code: SpanStatusCode.OK });
      return result;
    } catch (error: any) {
      span.setStatus({ code: SpanStatusCode.ERROR, message: error.message });
      span.recordException(error);
      throw error;
    } finally {
      span.end();
    }
  });
}

Logging Strategy

Structured Logging

import pino from 'pino';

const logger = pino({
  name: 'posthog',
  level: process.env.LOG_LEVEL || 'info',
});

function logPostHogOperation(
  operation: string,
  data: Record<string, any>,
  duration: number
) {
  logger.info({
    service: 'posthog',
    operation,
    duration_ms: duration,
    ...data,
  });
}

Alert Configuration

Prometheus AlertManager Rules

# posthog_alerts.yaml
groups:
  - name: posthog_alerts
    rules:
      - alert: PostHogHighErrorRate
        expr: |
          rate(posthog_errors_total[5m]) /
          rate(posthog_requests_total[5m]) > 0.05
        for: 5m
        labels:
          severity: warning
        annotations:
          summary: "PostHog error rate > 5%"

      - alert: PostHogHighLatency
        expr: |
          histogram_quantile(0.95,
            rate(posthog_request_duration_seconds_bucket[5m])
          ) > 2
        for: 5m
        labels:
          severity: warning
        annotations:
          summary: "PostHog P95 latency > 2s"

      - alert: PostHogDown
        expr: up{job="posthog"} == 0
        for: 1m
        labels:
          severity: critical
        annotations:
          summary: "PostHog integration is down"

Dashboard

Grafana Panel Queries

{
  "panels": [
    {
      "title": "PostHog Request Rate",
      "targets": [{
        "expr": "rate(posthog_requests_total[5m])"
      }]
    },
    {
      "title": "PostHog Latency P50/P95/P99",
      "targets": [{
        "expr": "histogram_quantile(0.5, rate(posthog_request_duration_seconds_bucket[5m]))"
      }]
    }
  ]
}

Instructions

Step 1: Set Up Metrics Collection

Implement Prometheus counters, histograms, and gauges for key operations.

Step 2: Add Distributed Tracing

Integrate OpenTelemetry for end-to-end request tracing.

Step 3: Configure Structured Logging

Set up JSON logging with consistent field names.

Step 4: Create Alert Rules

Define Prometheus alerting rules for error rates and latency.

Output

• Metrics collection enabled
• Distributed tracing configured
• Structured logging implemented
• Alert rules deployed

Error Handling

Issue	Cause	Solution
Missing metrics	No instrumentation	Wrap client calls
Trace gaps	Missing propagation	Check context headers
Alert storms	Wrong thresholds	Tune alert rules
High cardinality	Too many labels	Reduce label values

Examples

Quick Metrics Endpoint

app.get('/metrics', async (req, res) => {
  res.set('Content-Type', registry.contentType);
  res.send(await registry.metrics());
});

Resources

• Prometheus Best Practices
• OpenTelemetry Documentation
• PostHog Observability Guide

Next Steps

For incident response, see posthog-incident-runbook.