Posthog Multi Env Setup

PostHog Multi-Environment Setup

Overview

Separate PostHog projects per environment is strongly recommended over using one project with event filtering. Each environment gets its own Project API Key (starts with phc_) and Project ID.

Prerequisites

• PostHog Cloud account or self-hosted instance
• Separate PostHog projects for dev, staging, and production
• Project API keys (phc_...) and Project IDs for each environment
• Personal API key for admin operations (optional)

Environment Strategy

Instructions

Step 1: Create Separate PostHog Projects

PostHog Cloud: app.posthog.com > New Project
- "myapp-development" -> copy phc_... API key
- "myapp-staging"     -> copy phc_... API key
- "myapp-production"  -> copy phc_... API key

Step 2: Environment-Specific PostHog Configuration

// config/posthog.ts
type Env = "development" | "staging" | "production";

interface PostHogConfig {
  apiKey: string;                   // phc_... project key
  host: string;                     // app.posthog.com or self-hosted URL
  sessionRecording: boolean;
  samplingRate: number;             // 0-1 for session recording
}

const configs: Record<Env, PostHogConfig> = {
  development: {
    apiKey: process.env.NEXT_PUBLIC_POSTHOG_KEY_DEV!,
    host: "https://app.posthog.com",
    sessionRecording: false,         // never record in dev
    samplingRate: 0,
  },
  staging: {
    apiKey: process.env.NEXT_PUBLIC_POSTHOG_KEY_STAGING!,
    host: "https://app.posthog.com",
    sessionRecording: false,         // no recordings in staging
    samplingRate: 0,
  },
  production: {
    apiKey: process.env.NEXT_PUBLIC_POSTHOG_KEY_PROD!,
    host: "https://app.posthog.com",
    sessionRecording: true,
    samplingRate: 0.25,              // record 25% of sessions
  },
};

export function getPostHogConfig(): PostHogConfig {
  const env = (process.env.NODE_ENV || "development") as Env;
  const config = configs[env] || configs.development;
  if (!config.apiKey) {
    console.warn(`PostHog API key not set for ${env} -- analytics disabled`);
  }
  return config;
}

Step 3: Next.js PostHog Provider

// app/providers.tsx
"use client";
import posthog from "posthog-js";
import { PostHogProvider } from "posthog-js/react";
import { useEffect } from "react";
import { getPostHogConfig } from "../config/posthog";

export function PHProvider({ children }: { children: React.ReactNode }) {
  const config = getPostHogConfig();

  useEffect(() => {
    if (!config.apiKey) return;

    posthog.init(config.apiKey, {
      api_host: config.host,
      disable_session_recording: !config.sessionRecording,
      session_recording: config.sessionRecording
        ? { sampleRate: config.samplingRate }
        : undefined,
      capture_pageview: false,     // use usePathname in Next.js App Router
      loaded: (ph) => {
        if (process.env.NODE_ENV === "development") {
          ph.debug();
        }
      },
    });
  }, []);

  return <PostHogProvider client={posthog}>{children}</PostHogProvider>;
}

Step 4: Server-Side Node.js Setup

// lib/posthog-server.ts
import { PostHog } from "posthog-node";

let _client: PostHog | null = null;

export function getPostHogServer(): PostHog {
  if (_client) return _client;

  const config = getPostHogConfig();
  if (!config.apiKey) return { capture: () => {} } as any; // no-op if unconfigured

  _client = new PostHog(config.apiKey, {
    host: config.host,
    flushAt: 20,
    flushInterval: 10000,  # 10000: 10 seconds in ms
  });

  return _client;
}

Step 5: Environment Variable Setup

# .env.local
NEXT_PUBLIC_POSTHOG_KEY_DEV=phc_dev_abc123
POSTHOG_PROJECT_ID_DEV=12345  # port 12345 - example/test

# .env.staging
NEXT_PUBLIC_POSTHOG_KEY_STAGING=phc_staging_def456
POSTHOG_PROJECT_ID_STAGING=12346  # 12346 = configured value

# Production (GitHub Actions / cloud secret manager)
# NEXT_PUBLIC_POSTHOG_KEY_PROD=phc_prod_xyz789
# POSTHOG_PROJECT_ID_PROD=12347

Error Handling

Examples

Verify Environment Routing

import { getPostHogConfig } from "./config/posthog";

const cfg = getPostHogConfig();
console.log(`PostHog key: ${cfg.apiKey.slice(0, 10)}...`);
console.log(`Session recording: ${cfg.sessionRecording ? "ON" : "OFF"}`);

Feature Flag Rollout Per Environment

// Staging project: 100% rollout for QA
// Production project: 10% initial rollout
const flagValue = await posthogServer.getFeatureFlag("new-checkout", userId);

Resources

• PostHog Multi-Environment Guide
• PostHog Next.js Integration
• PostHog Node.js SDK

Next Steps

For webhook setup, see posthog-webhooks-events.

Output

• Configuration files or code changes applied to the project
• Validation report confirming correct implementation
• Summary of changes made and their rationale