sensor2json

Exposes GPIO sensor data via JSON REST endpoint. This repo builds an ARM compatible Docker image that will output the values of DS18B20 or BMP180 temperature/altitude/barometric pressure sensors connected to a Raspberry Pi. This library can be extended to serve up any GPIO sensors. Pull Requests are welcome. Built using Python Flask.

GPIO Sensors are hard, use REST!

The container binds to a provided port and outputs the sensor data in easy to ingest JSON blobs.

🍺  pi@bar[~] > docker run --rm -d --privileged -p 8800:8800 -t bgulla/sensor2json
🍺  pi@bar[~] > curl http://bar.local:8800/stats | jq "."
{
  "bmp180": { 
    "temperatureF": 69.25999999999999,
    "pressure": 100665,
    "altitude": 54.34029119011573,
    "temperature": 20.7
  },
  "ds18b20": {
    "28-00000483ba1a": 67.4366,
    "28-00000471c98d": 39.5366
  }
}

Requirements

DS18B20 Temperature Sensor

Adafruit has an awesome guide but in short do the following commands:

echo 'dtoverlay=w1-gpio' >> /boot/config.txt
echo 'w1-gpio' >> /etc/modules
echo 'w1-therm' >> /etc/modules
reboot

BMP180 Temperature/Barometric/Altitude Sensor

echo "dtparam=i2c1=on" >> /boot/config.txt
echo "dtparam=i2c_arm=on">> /boot/config.txt
echo "i2c-dev" >> /etc/modules
reboot

How to build

Building the image is straight forward:

• Git clone this repo
• docker build -t sensor2json

Aliases

Sensor IDs don't tell a story, but aliases do. All DS18b20 sensors have an id in the format 28-<sensor_id>. If you attach environment variables prepended with 'sensor_', the webserver will actually replace the sensor id with a string value.

Example:

pi@bar[~] > docker run -t -p 8800:8800 -e 'sensor_00000483ba1a=kegerator' --privileged bgulla/sensor2json
pi@bar[~] > curl http://bar.local:8800/stats | jq "."
{
  "bmp180": {},
  "ds18b20": {
    "28-00000483ba1a": 67.4366,
    "kegerator": 39.5366
  }
}

Telegraf/InfluxDB (+Grafana) Plugin

Graphs are awesome! I am am a huge fan of InfluxDB + Grafana. My shipping agent of choice is Telegraf. Telegraf will parse the GET request to your rest endpoint and automagically send it to InfluxDB.

Add the folllowing to your /etc/telegraf/telegraf.conf file:

[[inputs.httpjson]]
  name = "bar_stats"
# URL of each server in the service's cluster
  servers = [
    "http://localhost:8800/stats",
  ]
# Set response_timeout (default 5 seconds)
  response_timeout = "5s"
# HTTP method to use: GET or POST (case-sensitive)
  method = "GET"