Breadcrumb

A self-contained Go server that receives GPS location data from the Colota Android app, stores it in an SQLite3 database, and serves a web frontend for browsing trips on a map.

Quick Start

# Build
go build -o breadcrumb .

# Run (no auth, default port 8080, db = ./locations.db)
./breadcrumb

# Run with Bearer token auth on port 443
./breadcrumb -port 443 -token mysecrettoken -db /var/data/locations.db

Flags

Flag	Default	Description
-port	8080	HTTP listen port
-db	locations.db	Path to the SQLite3 database file
-token	(empty)	Bearer token for auth. Empty = authentication off.

---

API

POST /api/location ← Colota app sends here

Headers: Content-Type: application/json

Body (Colota default payload):

{
  "lat":  51.495065,
  "lon":  -0.043945,
  "acc":  12,
  "alt":  519,
  "vel":  0,
  "batt": 85,
  "bs":   2,
  "tst":  1704067200,
  "bear": 180.5
}

Field	Type	Required	Description
lat	float	✓	Latitude (decimal degrees)
lon	float	✓	Longitude (decimal degrees)
acc	float	✓	Accuracy (metres)
tst	int	✓	Unix timestamp (seconds). Falls back to server time.
alt	float		Altitude (metres)
vel	float		Speed (m/s)
bear	float		Bearing (degrees, 0–360)
batt	int		Battery level (0–100 %)
bs	int		Battery state: 0=unknown 1=unplugged 2=charging 3=full

GET variant is also supported (query parameters with the same field names).

Returns: 200 OK on success.

---

GET /api/locations ← Query stored locations

Param	Default	Description
limit	100	Max records to return (up to 500 000)
page	1	Page number (1-based)
from		Filter: Unix timestamp lower bound
to		Filter: Unix timestamp upper bound

Response:

{
  "total":   42,
  "page":    1,
  "limit":   100,
  "records": [ { "id": 1, "lat": 51.495065, "lon": -0.043945, ... } ]
}

---

GET /api/trips

Returns location points grouped into trips (gaps > 30 min = new trip), newest first.

---

GET /health

Returns server status and total location count.

---

Colota App Configuration

1. Open Colota → Settings → API Settings
2. Select template: Custom
3. Set Endpoint URL to http(s)://your-server:8080/api/location
4. HTTP Method: POST
5. If using a token: set Authentication → Bearer Token to your -token value
6. Leave field mapping at defaults
7. Tap Test Connection — you should see 200 OK

---

Docker

docker build -t breadcrumb .

docker run -d \
  --name breadcrumb \
  -p 8080:8080 \
  -v breadcrumb-data:/data \
  breadcrumb -token "$TOKEN"

---

Database Schema

CREATE TABLE locations (
  id          INTEGER PRIMARY KEY AUTOINCREMENT,
  lat         REAL    NOT NULL,
  lon         REAL    NOT NULL,
  acc         REAL    NOT NULL,
  alt         REAL,
  vel         REAL,
  batt        INTEGER,
  bs          INTEGER,
  tst         INTEGER NOT NULL,   -- Unix timestamp
  bear        REAL,
  received_at TEXT    NOT NULL    -- ISO-8601 UTC
);
CREATE INDEX idx_locations_tst ON locations(tst);