ActivityPub

A multi-tenant ActivityPub server for Ghost, built with Fedify. This service makes it possible for independent websites to publish their content directly to the Fediverse, enabling networked publishing to the open social web.

Running locally for development

Ghost's host-based pnpm dev proxies /.ghost/activitypub/*, /.well-known/webfinger, and /.well-known/nodeinfo to this service (default target 127.0.0.1:8080). This setup has only been tested on macOS using Docker for Mac and OrbStack.

Setup

1. Install Ghost using Install from source instructions
2. Start the ActivityPub Service

1. Expose Ghost's development port with Tailscale (or ngrok)

1. Start Ghost with the public URL

ACTIVITYPUB_PROXY_TARGET=127.0.0.1:8080 url=https://<your-tailnet-or-ngrok-url>/ pnpm dev

🏗️ Architecture & Development Guidelines

For AI assistants: See AGENTS.md for comprehensive guidance with code examples.

For developers: See Architecture Decision Records in /adr for detailed rationale.

Core Architecture Patterns

This service follows Domain-Driven Design with specific patterns:

• Immutable Entities with Events (ADR-0003) - Entities return new instances with domain events
• Result Type Pattern (ADR-0004) - Use Result for explicit error handling
• Error Objects in Results (ADR-0005) - Enhanced Result types with contextual error objects
• Class-Based Architecture (ADR-0006) - All components use classes with dependency injection
• Repository Pattern (ADR-0007) - Services orchestrate logic, repositories handle data access
• View Pattern for Reads (ADR-0008) - Optimized read queries separate from write path
• Hash-Based Lookups (ADR-0009) ⚠️ - ActivityPub IDs use SHA256 hashes
• Decorator Routing (ADR-0010) - Routes defined via decorators

Project Structure

src/
├── account/            # Immutable entities
├── post/               # Being migrated to immutable
├── activity-handlers/  # Class-based handlers
├── http/api/           # REST controllers
├── core/               # Shared utilities
└── dispatchers.ts      # Legacy - don't add here

⚠️ Critical Gotchas

1. Database lookups MUST use SHA256 hashes (ADR-0009)

• Never use where('ap_id', apId) - it returns empty results silently!
• Always use whereRaw('ap_id_hash = UNHEX(SHA2(?, 256))', [apId])
• Applies to: ap_id, domain (with LOWER), ap_inbox_url (with LOWER)

• Use isError(result), getValue(result), getError(result)
• Never destructure directly like [error, value]

• Views can query DB directly (read optimization)
• Services MUST go through repositories (write path)

• Parameter accountService → registered as 'accountService'
• Parameter db → registered as 'db'

• Adding to dispatchers.ts → create new handler classes
• Using AccountType → use Account entity
• Direct DB queries in services → use repositories
• String comparisons for AP IDs → use hash lookups

Code formatting + linting

We use Biome for code formatting and linting.

If you use VS Code, you can install the Biome extension to get inline feedback.

To enable auto-formatting on save, you'll need to set the default formatter to Biome and enable Format on Save in your VS Code settings.

Running Tests

Tests run within a Docker Compose stack. Common commands:

• pnpm test — run everything (types, unit, integration, and e2e); slow
• pnpm test:unit — unit tests only; fast
• pnpm test:integration — integration tests only
• pnpm test:cucumber — end-to-end (Cucumber) tests
• pnpm test:single 'path/to/test' — run a single unit or integration test
• pnpm test:types — type-check with tsc

Migrations

Run pnpm migrate to apply pending up migrations against your dev db (this also happens automatically on pnpm dev). For the testing db, use docker compose run migrate-testing up.

To run other migrate commands, drop into a shell with docker compose exec -it migrate /bin/sh (or migrate-testing). The migrate binary is available there, along with a MYSQL_DB environment variable correctly formatted for the -database argument.

Copyright & license

Copyright (c) 2013-2026 Ghost Foundation - Released under the MIT license. Ghost and the Ghost Logo are trademarks of Ghost Foundation Ltd. Please see our trademark policy for info on acceptable usage.