sng_exporter.py

#!/usr/bin/env python3

import argparse
import logging
import socket
from http.server import BaseHTTPRequestHandler, HTTPServer
from logging.handlers import SysLogHandler

logger = logging.getLogger(__name__)


def setup_logging(log_level, log_target):
    numeric_level = getattr(logging, log_level.upper(), None)
    if not isinstance(numeric_level, int):
        raise ValueError(f"Invalid log level: {log_level}")
    logger.setLevel(numeric_level)

    formatter = logging.Formatter('%(levelname)s - %(message)s')

    if log_target == "syslog":
        syslog_handler = SysLogHandler(address='/dev/log')
        syslog_handler.setFormatter(formatter)
        logger.addHandler(syslog_handler)
    elif log_target == "stderr":
        console_handler = logging.StreamHandler()
        console_handler.setFormatter(formatter)
        logger.addHandler(console_handler)
    else:
        raise ValueError(f"Invalid log target: {log_target}")


class PrometheusRequestHandler(BaseHTTPRequestHandler):
    socket_path = None
    stats_with_legacy = None
    data = None

    def handle(self):
        self.data = self.fetch_syslog_stats(self.socket_path, self.stats_with_legacy)
        BaseHTTPRequestHandler.handle(self)

    def do_GET(self):
        if self.path == '/metrics':
            self.send_response(200)
            self.send_header('Content-type', 'text/plain; version=0.0.4')
            self.end_headers()
            self.wfile.write(self.data)

    def fetch_syslog_stats(self, socket_path, stats_with_legacy):
        logger.debug("Fetching syslog-ng stats")
        with self.create_socket_connection(socket_path) as sock:
            message = stats_with_legacy
            sock.send(message.encode())

            response = b''
            while True:
                chunk = sock.recv(1024)
                response += chunk
                if not chunk or b'.\n' in chunk:
                    break

            logger.debug(f"Received:\n{response.decode()}")
            return response.strip()[:-1]

    @staticmethod
    def create_socket_connection(socket_path):
        sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
        sock.settimeout(10)
        try:
            sock.connect(socket_path)
            logger.debug("Successfully connected to syslog-ng-ctl socket")
        except socket.error as e:
            logger.error(f"Socket connection error: {e}: {socket_path}")
            raise

        return sock


class SngExporterServer:
    def __init__(self, listen_address, socket_path, stats_type):
        PrometheusRequestHandler.socket_path = socket_path
        PrometheusRequestHandler.stats_with_legacy = stats_type
        self.server = HTTPServer((listen_address.split(":")[0], int(listen_address.split(":")[1])),
                                 PrometheusRequestHandler)
        try:
            self.server.serve_forever()
            logger.info("Service successfully started")
        except KeyboardInterrupt:
            self.server.server_close()
            logger.info("Service stopped")

    def server_close(self):
        self.server.socket.close()


def parse_arguments():
    parser = argparse.ArgumentParser(
        description="Command line script to export syslog-ng stats to Prometheus.",
        formatter_class=argparse.ArgumentDefaultsHelpFormatter)
    parser.add_argument("--listen-address", dest="listen_address", help="Service listen address", default=":9577")
    parser.add_argument("--socket-path", dest="socket_path", help="Path to the syslog-ng-ctl socket",
                        default='/var/lib/syslog-ng/syslog-ng.ctl')
    parser.add_argument("--stats-with-legacy", dest="stats_with_legacy", action="store_true",
                        help="Also include legacy statistics")
    parser.add_argument("--log-level", dest="log_level", help="Only log messages with the given severity or above. "
                                                              "One of: [debug, info, error]", default="info")
    parser.add_argument("--log-target", dest="log_target", default="stderr", help="Set the log target [stderr, syslog]")
    return parser.parse_args()


def main():
    args = parse_arguments()

    stats = "STATS PROMETHEUS WITH_LEGACY\n" if args.stats_with_legacy else "STATS PROMETHEUS\n"

    setup_logging(args.log_level, args.log_target)
    logger.info("Starting syslog-ng exporter...")
    logger.debug(f"Socket Path: {args.socket_path}")
    logger.debug(f"Listen address: {args.listen_address}")
    logger.debug(f"Stats with Legacy: {stats}")

    logger.debug("Checking syslog-ng-ctl socket")
    try:
        PrometheusRequestHandler.create_socket_connection(args.socket_path).close()
    except socket.error:
        logger.error("Failed to connect to syslog-ng-ctl socket. Exiting.")
        return

    SngExporterServer(args.listen_address, args.socket_path, stats)


if __name__ == "__main__":
    main()