SignalK to GreptimeDB Plugin

A native SignalK server plugin to ingest data into GreptimeDB using the InfluxDB Line Protocol (ILP) over HTTP.

This plugin allows for high-performance, schemaless ingestion of Signal K data into GreptimeDB. By using the Influx Line Protocol, tables are automatically created for each Signal K path, and tags are indexed for efficient querying.

Features

• Influx Line Protocol (ILP): Uses the industry-standard protocol for high-throughput time-series data.
• Dynamic Schema: Automatically creates tables (measurements) based on Signal K paths (e.g., navigation.speedOverGround).
• Tagging: Automatically tags data with vessel (URN) and source for rich query capabilities.
• Batching: Buffers incoming deltas and flushes them in batches to reduce network requests.
• Configurable: Fully configurable via the SignalK Admin UI.

Installation

From AppStore (Recommended)

1. Open your SignalK Admin UI.
2. Go to Appstore -> Available.
3. Search for signalk-to-greptimedb.
4. Click Install.

Manual Installation

cd /path/to/signalk/
npm install signalk-to-greptimedb

Configuration

After installation, configure the plugin in Server -> Plugin Config:

• GreptimeDB Host: Hostname of your GreptimeDB instance (default: greptimedb or localhost).
• GreptimeDB HTTP Port: usually 4000 (default: 4000).
• Database Name: Database to write to (default: public).
• Username: Database username (if authentication is enabled).
• Password: Database password (if authentication is enabled).
• Batch Size: Number of points to buffer before sending (default: 500).
• Flush Interval: Maximum time (ms) to wait before sending a batch (default: 1000).

Data Schema & Querying

Data is stored using the InfluxDB Line Protocol model:

• Measurement (Table): The Signal K path (e.g., navigation.speedOverGround).
• Tags:
  • vessel: The vessel URN (e.g., urn:mrn:signalk:uuid:...).
  • source: The source label or talker ID.
• Fields:
  • value: The sensor value (number, string, or boolean).
• Timestamp: The time of the update (in nanoseconds).

Example Query (SQL)

You can query the data using standard SQL in GreptimeDB:

-- Get the last 10 speed readings
SELECT * FROM "navigation.speedOverGround" ORDER BY greptime_timestamp DESC LIMIT 10;

GreptimeDB Installation Guide

Docker (Recommended)

Add this service to your docker-compose.yml:

services:
  greptimedb:
    image: greptime/greptimedb:latest
    container_name: greptimedb
    restart: unless-stopped
    ports:
      - "4000:4000"
      - "4001:4001"
      - "4002:4002"
      - "4003:4003"
    volumes:
      - greptimedb-data:/var/lib/greptimedb
    command: standalone start --http-addr 0.0.0.0:4000

volumes:
  greptimedb-data:

License

Apache-2.0