fitbit-metrics.maxhogan.dev

Convert Fitbit health data into Prometheus metrics.

Cloudflare Worker that exposes Fitbit health data as a Prometheus-compatible /metrics endpoint. Includes sleep, RHR, HR zone, HRV, skin temp, SpO2, calories, steps, distance, & floors. Built with Hono + TS.

Requirements

  1. Prometheus
  2. A Fitbit account

Steps

  1. Authorize this app with your Fitbit account
  2. Save the API token returned from step 1
  3. Configure your Prometheus server to scrape /metrics using your saved API token (using Authorization: Bearer abcd1234-... header or ?token=abcd1234-...)
- job_name: fitbit
  scrape_interval: 15m
  scheme: https
  authorization:
    type: Bearer
    credentials: "abcd1234-..."
  static_configs:
    - targets: ["fitbit-metrics.maxhogan.dev"]

Metrics are cached for 12 hours on the server-side, so scrape_interval can be pretty aggressive if you want but updated data may be delayed.

Links

Metrics

All metrics are Prometheus gauges, labeled by date (and additional labels where noted). Data covers the last 30 days per scrape.

Metric Description Labels
fitbit_sleep_hours_asleep Total hours asleep date
fitbit_sleep_hours_in_bed Total hours in bed date
fitbit_sleep_efficiency Sleep efficiency score (0–100) date
fitbit_sleep_stage_minutes Minutes in each sleep stage date, stage
fitbit_resting_heart_rate Resting heart rate (bpm) date
fitbit_heart_rate_zone_minutes Minutes in each HR zone date, zone
fitbit_hrv_daily_rmssd Daily RMSSD HRV (ms) date
fitbit_hrv_deep_rmssd Deep-sleep RMSSD HRV (ms) date
fitbit_skin_temp_nightly_relative Skin temp deviation from baseline (°C) date
fitbit_spo2_avg Average SpO2 % date
fitbit_spo2_min Minimum SpO2 % date
fitbit_spo2_max Maximum SpO2 % date
fitbit_breathing_rate Breathing rate (breaths/min) date
fitbit_steps Daily step count date
fitbit_calories Daily calories burned date
fitbit_distance Daily distance (km) date
fitbit_distance_mi Daily distance (miles) date
fitbit_floors Daily floors climbed date

Routes

Route Auth Description
GET /authorize None Starts Fitbit OAuth2 flow
GET /callback Via state OAuth2 callback, returns your API token
GET /metrics Bearer Prometheus scrape endpoint
GET /purge Bearer Clears the KV response cache for your account
GET /doc None OpenAPI 3.0 JSON spec
GET /reference None Scalar API reference UI
GET /llms.txt None Plain text README for LLMs

Development

Setup

npm install

Secrets

Variable Description
FITBIT_CLIENT_ID Fitbit app client ID
FITBIT_CLIENT_SECRET Fitbit app client secret 
npx wrangler secret put FITBIT_CLIENT_ID
npx wrangler secret put FITBIT_CLIENT_SECRET

Dev

npx wrangler dev

Deploy

npx wrangler deploy