webhooker

webhooker is a Go web application by @sneak that receives, stores, and proxies webhooks to configured targets with retry support, observability, and a management web UI. License: MIT.

Getting Started

# Clone the repo
git clone https://git.eeqj.de/sneak/webhooker.git
cd webhooker

# Install dependencies
make deps

# Copy example config
cp configs/config.yaml.example config.yaml

# Run in development mode
make dev

# Run all checks (format, lint, test, build)
make check

# Build Docker image
make docker

Environment Variables

• WEBHOOKER_ENVIRONMENT — dev or prod (default: dev)
• DEBUG — Enable debug logging
• PORT — Server port (default: 8080)
• DBURL — Database connection string
• SESSION_KEY — Base64-encoded 32-byte session key (required in prod)
• METRICS_USERNAME — Username for metrics endpoint
• METRICS_PASSWORD — Password for metrics endpoint
• SENTRY_DSN — Sentry error reporting (optional)

Rationale

Webhook integrations between services are fragile: the receiving service must be up when the webhook fires, there is no built-in retry for most webhook senders, and there is no visibility into what was sent or when. webhooker solves this by acting as a reliable intermediary that receives webhooks, stores them, and delivers them to configured targets — with optional retries, logging, and Prometheus metrics for observability.

Use cases include:

• Store-and-forward with unlimited retries for unreliable receivers
• Prometheus/Grafana metric analysis of webhook frequency, size, and handler performance
• Introspection and debugging of webhook payloads
• Redelivery of webhook events for application testing
• Fan-out delivery of webhooks to multiple targets
• HA ingestion endpoint for delivery to less reliable systems

Design

Architecture

webhooker uses Uber's fx dependency injection library for managing application lifecycle. It uses log/slog for structured logging, GORM for database access, and SQLite (via modernc.org/sqlite, pure Go, no CGO) for storage. HTTP routing uses chi.

Rate Limiting

Global rate limiting middleware (e.g. per-IP throttling applied at the router level) must not apply to webhook receiver endpoints (/webhook/{uuid}). Webhook endpoints receive automated traffic from external services at unpredictable rates, and blanket rate limits would cause legitimate webhook deliveries to be dropped.

Instead, each webhook endpoint has its own individually configurable rate limit, applied within the webhook handler itself. By default, no rate limit is applied — webhook endpoints accept traffic as fast as it arrives. Rate limits can be configured on a per-webhook basis in the application when needed (e.g. to protect against a misbehaving sender).

Database Architecture

webhooker uses separate SQLite database files rather than a single monolithic database:

• Main application database — Stores application configuration and all standard webapp data: users, sessions, API keys, and global settings.
• Per-webhook databases — Each webhook gets its own dedicated SQLite database file containing: input logs, webhook logs, and all output queues for that specific webhook.

This separation provides several benefits: webhook databases can be independently backed up, rotated, or archived; a high-volume webhook won't cause lock contention or bloat affecting the main application; and individual webhook data can be cleanly deleted when a webhook is removed.

Package Layout

All application code lives under internal/ to prevent external imports. The main entry point is cmd/webhooker/main.go.

• internal/config — Configuration management via pkg/config (Viper-based)
• internal/database — GORM database connection, migrations, and models
• internal/globals — Global application metadata (version, build info)
• internal/handlers — HTTP handlers using the closure pattern
• internal/healthcheck — Health check endpoint logic
• internal/logger — Structured logging setup (log/slog)
• internal/middleware — HTTP middleware (auth, CORS, logging, metrics)
• internal/server — HTTP server setup and routing
• internal/session — Session management (gorilla/sessions)
• pkg/config — Reusable multi-environment configuration library
• static/ — Embedded static assets (CSS, JS)
• templates/ — Go HTML templates

Data Model

• Users — Service users with username/password (Argon2id hashing)
• Webhooks — Webhook processing units, many-to-one with users
• Entrypoints — Inbound URL endpoints feeding into webhooks
• Targets — Delivery destinations per webhook (HTTP, retry, database, log)
• Events — Captured webhook payloads
• Deliveries — Pairing of events with targets
• Delivery Results — Outcome of each delivery attempt
• API Keys — Programmatic access credentials per user

API Endpoints

• GET / — Web UI index page
• GET /.well-known/healthcheck — Health check with uptime, version
• GET /s/* — Static file serving (CSS, JS)
• GET /metrics — Prometheus metrics (requires basic auth)
• POST /webhook/{uuid} — Webhook receiver endpoint
• /pages/login, /pages/logout — Authentication
• /user/{username} — User profile
• /sources/* — Webhook source management

TODO

Phase 1: Security & Infrastructure

• Security headers (HSTS, CSP, X-Frame-Options)
• Rate limiting middleware
• CSRF protection for forms
• Request ID tracking through entire lifecycle

Phase 2: Authentication & Authorization

• Authentication middleware for protected routes
• Session expiration and "remember me"
• Password reset flow
• API key authentication for programmatic access

Phase 3: Core Webhook Features

• Webhook reception and event storage at /webhook/{uuid}
• Event processing and target delivery engine
• HTTP target type (fire-and-forget POST)
• Retry target type (exponential backoff)
• Database target type (store only)
• Log target type (console output)
• Webhook signature verification (GitHub, Stripe formats)

Phase 4: Web UI

• Webhook source management pages (list, create, edit, delete)
• Webhook request log viewer with filtering
• Delivery status and retry management UI
• Manual event redelivery
• Analytics dashboard (success rates, response times)

Phase 5: API

• RESTful CRUD for webhooks, entrypoints, targets
• Event viewing and filtering endpoints
• API documentation (OpenAPI)

Future

• Email source and delivery target types
• SNS, S3, Slack delivery targets
• Data transformations (e.g. webhook-to-Slack message)
• JSONL file delivery with periodic S3 upload

License

MIT License. See LICENSE for details.

Author

@sneak