Structured Logging and Prometheus Exports for Wireguard sessions

wg-monitor.py

#!/usr/bin/env python3
"""Wireguard logging and monitoring tool.

Logs the following events along with the peer state in JSON format to stdout:
- Peer connected (= successfull handshake after period of no handshakes)
- Peer disconnected (= no handshake for longer than 5 minutes)
- Peer roamed (= source IP of the peer changed)

Additionally, the tool exposes a Prometheus-compatible monitoring endpoint
on port 9000 that exports the following metrics:
- `wireguard_sent_bytes_total`: Bytes sent to the peer (counter)
- `wireguard_received_bytes_total`: Bytes received from the peer (counter)
- `wireguard_latest_handshake_seconds`: Seconds from the last handshake (gauge)


Requires Python >=3.7, but no additional libraries.

--------------------------------------------------------------------------------
Copyright 2020 Johannes Baiter <[email protected]>

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
Software, and to permit persons to whom the Software is furnished to do so, subject
to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
"""
from __future__ import annotations


import argparse
import http.server
import json
import re
import socketserver
import sys
import subprocess
import threading
import time
from datetime import datetime
from http import HTTPStatus
from typing import Any, List, Mapping, MutableMapping, NamedTuple, Optional, Tuple
from pathlib import Path


# Regular expression to parse friendly names for peers
PEER_NAME_PAT = re.compile(
    r"\[Peer\]\n# (?P<name>.+?)\nPublicKey = (?P<pubkey>.+?)\n", re.MULTILINE
)


class MetricsHandler(http.server.BaseHTTPRequestHandler):
    def log_request(self, *args, **kwargs):
        """ Dummy logging handler that just does nothing. """
        pass

    def do_GET(self):
        """ Return Prometheus metrics. """
        self.send_response(HTTPStatus.OK)
        self.send_header("Content-Type", "text/plain; version=0.0.4")
        self.end_headers()
        self.wfile.write("\n".join(export_metrics()).encode("utf8") + b"\n")


class RemotePeer(NamedTuple):
    """ State of a remote Wireguard peer. """

    device: str
    name: Optional[str]
    public_key: str
    remote_addr: Optional[str]
    allowed_ips: Tuple[str]
    latest_handshake: Optional[datetime]
    transfer_rx: int
    transfer_tx: int

    @classmethod
    def parse(cls, namemap: Mapping[str, str], *columns) -> RemotePeer:
        """ Parse a RemotePeer from a `wg show all dump` line. """
        dev, pub, _, remote_addr, ip_list, handshake_ts, bytes_rx, bytes_tx, _ = columns
        return cls(
            device=dev,
            name=namemap.get(pub),
            public_key=pub,
            remote_addr=remote_addr if remote_addr != "(none)" else None,
            allowed_ips=ip_list.split(","),
            latest_handshake=datetime.fromtimestamp(int(handshake_ts))
            if handshake_ts != "0"
            else None,
            transfer_rx=int(bytes_rx),
            transfer_tx=int(bytes_tx),
        )


def get_friendly_names() -> Mapping[str, str]:
    """ Parse human-readable name for peers from the Wireguard config. """
    ifaces = (
        subprocess.check_output(["wg", "show", "interfaces"]).decode("utf8").split()
    )
    name_map: MutableMapping[str, str] = {}
    for iface in ifaces:
        cfg = Path(f"/etc/wireguard/{iface}.conf").read_text()
        name_map.update((key, name) for name, key in PEER_NAME_PAT.findall(cfg))
    return name_map


def log_json(msg: str, peer: RemotePeer, **kwargs):
    payload = peer._asdict()
    if peer.latest_handshake is not None:
        payload["latest_handshake"] = peer.latest_handshake.isoformat()
    print(
        json.dumps(
            {
                "@timestamp": datetime.now().isoformat(),
                "message": msg,
                **payload,
                **kwargs,
            }
        )
    )


def get_peer_states() -> List[RemotePeer]:
    """ Get the state of all remote peers from Wireguard. """
    name_map = get_friendly_names()
    wg_out = subprocess.check_output(["wg", "show", "all", "dump"]).decode("utf8")
    rows = [l.split("\t") for l in wg_out.split("\n")]
    return [RemotePeer.parse(name_map, *row) for row in rows if len(row) > 5]


def is_peer_connected(last_handshake: Optional[datetime], timeout: int) -> bool:
    if last_handshake is None:
        last_handshake = datetime.fromtimestamp(0)
    since_handshake = datetime.now() - last_handshake
    return since_handshake.total_seconds() < timeout


def log_wireguard_peers(poll_delay: int, handshake_timeout: int):
    """Poll wireguard peer state and log connections/disconnections in JSON to stdout."""
    peer_state: MutableMapping[str, Tuple[bool, Optional[datetime], Optional[str]]] = {
        peer.public_key: (
            is_peer_connected(peer.latest_handshake, handshake_timeout),
            peer.latest_handshake,
            peer.remote_addr,
        )
        for peer in get_peer_states()
    }
    t = threading.currentThread()
    while True:
        peers = get_peer_states()
        for peer in peers:
            now_connected = is_peer_connected(peer.latest_handshake, handshake_timeout)
            if peer.public_key not in peer_state:
                log_json("New Peer registered", peer, connected=now_connected)
                peer_state[peer.public_key] = (
                    now_connected,
                    peer.latest_handshake,
                    peer.remote_addr,
                )
                continue
            previously_connected, previous_handshake, remote_addr = peer_state[
                peer.public_key
            ]
            if previously_connected and not now_connected:
                log_json("Peer disconnected", peer, connected=now_connected)
            elif not previously_connected and now_connected:
                log_json("Peer connected", peer, connected=now_connected)
            elif previously_connected and remote_addr != peer.remote_addr:
                log_json(
                    "Peer roamed",
                    peer,
                    connected=now_connected,
                    old_remote_addr=remote_addr,
                )
            peer_state[peer.public_key] = (
                now_connected,
                peer.latest_handshake,
                peer.remote_addr,
            )
        # Check if we're stopped
        for i in range(poll_delay * 10):
            if getattr(t, "stop_logging", False):
                return
            time.sleep(0.1)


def export_metrics() -> List[str]:
    """ Export metrics for all registered peers in the Prometheus text format. """
    peers = get_peer_states()
    tx = []
    rx = []
    handshakes = []
    for peer in peers:
        since_last_handshake = datetime.now() - (
            peer.latest_handshake or datetime.fromtimestamp(0)
        )
        info = f'interface="{peer.device}",public_key="{peer.public_key}",allowed_ips="{",".join(peer.allowed_ips)}",friendly_name="{peer.name}"'
        tx.append(f"wireguard_sent_bytes_total{{{info}}} {peer.transfer_tx}")
        rx.append(f"wireguard_received_bytes_total{{{info}}} {peer.transfer_rx}")
        handshakes.append(
            f"wireguard_latest_handshake_seconds{{{info}}} {since_last_handshake.total_seconds()}"
        )
    return [
        "# HELP wireguard_sent_bytes_total Bytes sent to the peer",
        "# TYPE wireguard_sent_bytes_total counter",
        *tx,
        "# HELP wireguard_received_bytes_total Bytes received from the peer",
        "# TYPE wireguard_received_bytes_total counter",
        *rx,
        "# HELP wireguard_latest_handshake_seconds Seconds from the last handshake",
        "# TYPE wireguard_latest_handshake_seconds gauge",
        *handshakes,
    ]


def start_metrics_server(port: int, bind: str):
    """ Start a HTTP server that serves Prometheus metrics in a background thread. """
    httpd = socketserver.TCPServer((bind, port), MetricsHandler)
    try:
        httpd.serve_forever()
    except KeyboardInterrupt:
        return


def main():
    parser = argparse.ArgumentParser(
        description=__doc__, formatter_class=argparse.RawTextHelpFormatter
    )
    parser.add_argument(
        "--poll-delay",
        dest="poll_delay",
        action="store",
        default=30,
        type=int,
        help="Period in seconds between polling of Wireguard state.",
    )
    parser.add_argument(
        "--handshake-timeout",
        dest="handshake_timeout",
        action="store",
        default=300,
        type=int,
        help="Minimum period in seconds between handshakes to consider a peer disconnected.",
    )
    parser.add_argument(
        "--metrics-port",
        dest="metrics_port",
        action="store",
        default=9000,
        type=int,
        help="Port to export the Prometheus metrics endpoint on.",
    )
    parser.add_argument(
        "--metrics-bind",
        dest="metrics_bind",
        action="store",
        default="0.0.0.0",
        type=str,
        help="Address to bind the metrics endpoint to.",
    )
    args = parser.parse_args()

    # Check if the user running the scripts is permitted to access the Wireguard state
    try:
        get_peer_states()
    except PermissionError:
        print("The tool needs to be run as the root user.")
        sys.exit(1)

    # Start logging and metrics endpoint
    logger_thread = threading.Thread(
        target=log_wireguard_peers, args=(args.poll_delay, args.handshake_timeout)
    )
    logger_thread.start()
    start_metrics_server(args.metrics_port, args.metrics_bind)
    logger_thread.stop_logging = True
    logger_thread.join()


if __name__ == "__main__":
    main()

Have you tried changing the listening address (--metrics-bind, defaults to 0.0.0.0) or the port (--metrics-port, defaults to 9000)? Looks like a problem in your environment, it seems that you can't bind to 0.0.0.0:9000

get_friendly_names() uses a hard coded path to the config file. wg has a built in function for printing the current config like so:
wg showconf <interface>
I noticed that this is a more stable and portable method to do it, when setting up a system based on FreeBSD, where the default config file location is not in /etc/wireguard/
Hope this is useful to someone.

also there is a repo with this functionality now: https://github.com/MindFlavor/prometheus_wireguard_exporter