Zapstore Relay

A Nostr relay and Blossom server for the Zapstore app ecosystem.

Features

Nostr Relay

• Full Nostr relay implementation using rely
• NIP-11 relay information document
• NIP-42 authentication support
• Configurable allowed event kinds with structure validation
• Filter specificity scoring to reject overly vague queries
• SQLite-based event storage

Blossom Server

• Full Blossom server implementation using blossy
• Bunny CDN integration for scalable blob delivery
• Configurable allowed media types (APKs, images)
• Deduplication: blobs are checked before upload to save bandwidth
• Local SQLite metadata store with CDN redirect for downloads

Access Control in Defender

• Access control is delegated to the Zapstore defender.
• Rate-limiting, cryptographic and structural validation is kept in the relay

Analytics

• Privacy-preserving usage statistics for app impressions and blob downloads
• Counts impressions derived from Nostr REQs
• Counts downloads from blossom downloads
• Batched, non-blocking writes: events are queued in memory and flushed to SQLite periodically or when the batch size threshold is reached

Rate Limiting

• Token bucket rate limiting per IP group
• Configurable initial tokens, max tokens, and refill rate
• Different costs for different operations (connections, events, queries, uploads)
• Penalty system for misbehaving clients

Running

Prerequisites

• Go 1.25 or later
• A BunnyCDN account with a storage zone configured
• A Nostr secret key loaded with Vertex DVM credits

Build and Run

Build the relay using the make command

# Clone the repository
git clone https://github.com/zapstore/relay.git
cd relay

# Build with default parameters:
# - TAG = <latest_tag>
# - BUILD_DIR = /build
make

# Or build with specific tag and build directory
make TAG=v1.2.3 BUILD_DIR=path/to/build

Run the relay using the simple cli

# Create and configure .env file
cp .env.example build/.env

# Edit build/.env with your configuration
nano build/.env

# Run (use the tag that was built)
./build/relay-v1.2.3 run

# Print the version
./build/relay-v1.2.3 version

# Print the active configuration
./build/relay-v1.2.3 config

Data Directory Structure

On first run, the server creates the following structure:

$SYSTEM_DIRECTORY_PATH/
├── analytics/
│   ├── analytics.db  # SQLite database for analytics
│   └── geo.mmdb      # MaxMind database for ip geolocation
│ 
└── data/
    ├── relay.db      # SQLite database for relay events
    └── blossom.db    # SQLite database for blob metadata

Endpoints

• Relay: ws://localhost:3334 (or your configured port)
• Blossom: http://localhost:3335 (or your configured port)
• Analytics: http://localhost:3336 (or your configured port)

Analytics API

All endpoints return a JSON array. Date parameters use the YYYY-MM-DD format and are inclusive.

GET /v1/app/impressions

Returns aggregated app impression counts recorded from Nostr REQs for kind 32267 app detail views.

Parameter	Type	Description
app_id	string	Filter to a specific app identifier
app_pubkey	string	Filter to a specific publisher pubkey
from	date	Start of date range (inclusive)
to	date	End of date range (inclusive)
source	string	Filter by client source: app, web, or unknown
type	string	Filter by impression type: detail
group_by	CSV	Grouping dimensions: app_id, app_pubkey, app_version, day, source, type, country_code

GET /v1/app/downloads

Returns aggregated app download counts recorded from Blossom requests for kind 3063 asset blobs.

Parameter	Type	Description
hash	string	Filter to a specific blob hash
app_id	string	Filter to a specific app identifier
app_pubkey	string	Filter to a specific publisher pubkey
from	date	Start of date range (inclusive)
to	date	End of date range (inclusive)
source	string	Filter by client source: app, web, or unknown
type	string	Filter by download type: install or update
group_by	CSV	Grouping dimensions: hash, app_id, app_version, app_pubkey, day, source, type, country_code

GET /v1/metrics/relay

Returns daily relay traffic metrics (REQ count, filter count, event count).

Parameter	Type	Description
from	date	Start of date range (inclusive)
to	date	End of date range (inclusive)

GET /v1/metrics/blossom

Returns daily Blossom server traffic metrics (check, download, and upload counts).

Parameter	Type	Description
from	date	Start of date range (inclusive)
to	date	End of date range (inclusive)