plot_kairosdb.py

#!/usr/bin/env python3

# kairosdb-downloader
# This Python code is an example of how to download metrics from KairosDB and plot them using matplotlib. Run it with:
# python plot_kairosdb.py

import json
from datetime import datetime

import matplotlib.dates as md
import matplotlib.pyplot as plt
import numpy as np
import requests

URL: str = 'http://kairosdb.icedc.se/api/v1/datapoints/query'

# Generated by the KairosDB web interface at http://kairosdb.icedc.se
# by selecting the metrics, tags, and aggregators you want to use
# and then clicking "Show Query"
QUERY = {
    "metrics": [
        {
            "tags": {
                "pod": [
                    "3"
                ],
                "deviceType": [
                    "str"
                ],
                "deviceNumber": [
                    "1",
                ]
            },
            "name": "humidity",
            "aggregators": [
                {
                    "name": "avg",
                    "sampling": {
                        "value": "1",
                        "unit": "seconds"
                    },
                    "align_start_time": True
                }
            ]
        }
    ],
    "plugins": [],
    "cache_time": 0,
    "start_relative": {
        "value": "20",
        "unit": "minutes"
    }
}


def main() -> None:
    # Sends a POST request to KairosDB with the QUERY in the body
    res = requests.post(
        URL,
        data=json.dumps(QUERY),
        headers={'Content-Type': 'application/json'},
        timeout=5
    ).json()

    # The values are in the format [[ms_timestamp, value], [ms_timestamp, value], ...]
    res_values = res['queries'][0]['results'][0]['values']
    # Extract the timestamps and convert to seconds since epoch
    timestamps = [x[0]/1000 for x in res_values]
    # Convert the timestamps to datetime objects
    dates = [datetime.fromtimestamp(ts) for ts in timestamps]
    datenums = md.date2num(dates)
    # Extract the values
    values = [x[1] for x in res_values]

    # Set the x-axis to be the formatted dates
    plt.subplots_adjust(bottom=0.2)
    plt.xticks(rotation=25)
    ax = plt.gca()
    xfmt = md.DateFormatter('%Y-%m-%d %H:%M:%S')
    ax.xaxis.set_major_formatter(xfmt)

    # Plot the values
    plt.plot(datenums, values)
    plt.show()


if __name__ == "__main__":
    main()