weather-exporter/main.py

"""
Present observational weather data to Prometheus
"""

import json
import time
import os

import requests
from flask import Flask, Response

app = Flask(__name__)


def fetch_weather_data(location: int, apikey: str) -> dict:
    """
    Fetch current data from the Met Office for the provided postcode
    """

    obs_data = requests.get(
        f'http://api.weatherapi.com/v1/current.json?'
        f'key={apikey}&'
        f'q={location}&'
        f'aqi=yes'
    )

    return json.loads(obs_data.content)


@app.route('/metrics')
def metrics():
    """
    Output Prometheus-style metrics
    """
    apikey = os.environ.get('WEATHER_APIKEY')
    location = os.environ.get('WEATHER_LOCATION')

    latest_data = fetch_weather_data(location, apikey)['current']

    ret_data = [
        {
            'key': 'sensor_weather_outdoor_temperature_celsius',
            'labels': {
                'location': location,
            },
            'type': 'gauge',
            'value': float(latest_data['temp_c']),
        },
        {
            'key': 'sensor_weather_outdoor_humidity_percent',
            'labels': {
                'location': location,
            },
            'type': 'gauge',
            'value': float(latest_data['humidity']),
        },
    ]

    ret_strs = list()
    for item in ret_data:
        ret_strs.append(f'# HELP {item["key"]} Weather metric')
        ret_strs.append(f'# TYPE {item["key"]} {item["type"]}')
        ret_strs.append(
            item["key"]
            + '{'
            + " ".join([f'{key}="{val}"' for key, val in item["labels"].items()])
            + '} '
            + str(item["value"])
        )

    resp = Response('\n'.join(ret_strs))
    resp.headers['Content-type'] = 'text/plain'

    return resp


if __name__ == '__main__':
    app.run(host='0.0.0.0')