simple_transmission_exporter.py

#!/usr/bin/env python3
import datetime
import json
import os
import sys
from collections import Counter

import transmissionrpc
from flask import Flask, make_response, request

METRIC_PREFIX = 'transmission'
PORT = 29091
# RPC direct query to obtain only torrents status
TORRENTS_QUERY = json.dumps({"method": "torrent-get", "arguments": {"fields": ["status"]}})
# the possible states a torrent can have
# source: https://github.com/transmission/transmission/blob/master/libtransmission/transmission.h#L1649-L1659
STATUS = {
    0: 'paused',
    1: 'queued_to_check',
    2: 'checking',
    3: 'queued_to_download',
    4: 'downloading',
    5: 'queued_to_seed',
    6: 'seeding',
}

# verify all the environment variables are set
for envvar in ["TRANSMISSION_HOST", "TRANSMISSION_PORT", "TRANSMISSION_USERNAME", "TRANSMISSION_PASSWORD"]:
    tmp = os.getenv(envvar)
    if not tmp:
        print(f'ERROR: required environment variable {envvar} is missing, exiting..')
        sys.exit(-1)
    exec(envvar + " = tmp")

app = Flask(__name__)


@app.route('/')
def homepage():
    """
    https://prometheus.io/docs/instrumenting/writing_exporters/#landing-page
    """
    landing_page = f"""A simple Prometheus exporter for Transmission
https://github.com/sandrotosi/simple-transmission-exporter

metric page: {request.host_url}metrics
"""
    response = make_response(landing_page, 200)
    response.mimetype = "text/plain"
    return response


@app.route('/metrics')
def metrics():
    _return = []
    start = datetime.datetime.now()
    tc = transmissionrpc.Client(address=TRANSMISSION_HOST, port=TRANSMISSION_PORT, user=TRANSMISSION_USERNAME, password=TRANSMISSION_PASSWORD)
    stats = tc.session_stats()

    for metric in ['downloadSpeed', 'download_dir_free_space', 'uploadSpeed']:
        _metric_name = f'{METRIC_PREFIX}_{metric}'
        _return.append((f'# TYPE {_metric_name}', 'gauge'))
        _return.append((_metric_name, stats._fields[metric].value))

    for metric in ['cumulative_stats', 'current_stats']:
        for item in ['downloadedBytes', 'filesAdded', 'secondsActive', 'sessionCount', 'uploadedBytes']:
            _metric_name = f'{METRIC_PREFIX}_{metric}_{item}'
            _return.append((f'# TYPE {_metric_name}', 'counter'))
            _return.append((_metric_name, stats._fields[metric].value[item]))

    # obtain torrents status counters
    # we need to query directly the RPC endpoint (still using transmissionrpc module for actually running the query)
    # as `get_torrents()` gets extremely slow for if the number of torrent is too high
    torrents = json.loads(tc._http_query(TORRENTS_QUERY))
    # initialize a counter with all the possible statuses
    status = Counter({1: 0, 2: 0, 3: 0, 4: 0, 5: 0, 6: 0})
    status.update(y['status'] for y in torrents['arguments']['torrents'])
    for status_id, status_text in STATUS.items():
        _metric_name = f'{METRIC_PREFIX}_status_{status_text}'
        _return.append((f'# TYPE {_metric_name}', 'gauge'))
        _return.append((_metric_name, status[status_id]))

    # https://prometheus.io/docs/instrumenting/writing_exporters/#metrics-about-the-scrape-itself
    _metric_name = f'{METRIC_PREFIX}_scrape_duration_seconds'
    _return.append((f'# TYPE {_metric_name}', 'gauge'))
    _return.append((_metric_name, (datetime.datetime.now() - start).total_seconds()))

    response = make_response('\n'.join([f'{x[0]} {x[1]}' for x in _return]), 200)
    response.mimetype = "text/plain"
    return response


if __name__ == '__main__':
    app.run(debug=False, port=PORT, host='0.0.0.0')