signalk-entropy-saillog

v1.1.1

Published

20 days ago

Signal K plugin that pushes position data to the entropysaillog tracker ingest (fork of signalk-saillogger)

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johnsocp

signalk-node-server-plugin

signalk-entropy-saillog

A Signal K plugin that pushes position data to your entropysaillog tracker ingest. A fork of signalk-saillogger repointed at your own POST /ingest endpoint: it collects position, SOG, and COG from Signal K, buffers them through connectivity dropouts, and pushes batches.

The saillogger.com metadata / AIS / monitoring-config push paths are removed — this fork only feeds the live tracker.

Install

In the Signal K server Appstore, search for signalk-entropy-saillog, install it, and restart the server. (It's published to npm with the signalk-node-server-plugin keyword, so it appears in the Appstore like any other plugin — no shell/SSH access needed.)

Configure

In the Signal K plugin config:

Ingest URL — your POST /ingest endpoint, e.g. https://xxxxx.execute-api.us-west-2.amazonaws.com/ingest
HMAC signing secret (recommended) — signs each push with x-timestamp + x-signature. Set this and leave the API key empty.
API key (optional fallback) — sent as x-api-key; only used when no secret is set. Provide a secret OR an API key (endpoint plus at least one credential is required).
GPS source (optional) — restrict to one GPS $source if you have several.

What it sends

Each push is one versioned-contract batch:

{
  "schema_version": 1,
  "batch_id": "<firstTs>-<lastTs>-<count>",
  "points": [
    { "timestamp": "2026-06-16T03:00:00.000Z", "lat": 26.70, "lon": -77.20, "sog": 6.5, "cog": 110.0 }
  ]
}

Auth: with a secret configured, each push is signed — HMAC-SHA256 over "<x-timestamp>.<body>" sent as x-signature (mirrors the server's auth.py); the server rejects stale timestamps and bad signatures. Without a secret it falls back to the x-api-key header.
Durable idempotency: batch_id is derived from the buffered rows (timestamp range + count). The buffer is persisted on disk, so after a plugin restart the same rows produce the same id — a resend overwrites the same object server-side instead of duplicating track points.
On HTTP 200 the sent rows are flushed from the buffer; on transient errors the buffer is kept and retried; an HTTP 400 (contract rejection) drops the batch so it can't wedge the queue.

Develop

npm install          # no runtime dependencies (native http/https)
npm test             # unit tests: payload builder, signing, and the http POST

lib/payload.js builds the contract payload + the durable batch_id; it is pure and unit-tested so the plugin's output provably matches the ingest contract. lib/auth.js mirrors the server's HMAC signing byte-for-byte. lib/http.js is a tiny native-https JSON POST (the plugin has zero runtime dependencies).

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signalk-entropy-saillog

Install

Configure

What it sends

Develop

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