perfect-postcode/finder/http_client.py

import logging
import random
import threading
import time

import httpx
from fake_useragent import UserAgent

from constants import MAX_RETRIES, RETRY_BASE_DELAY
from metrics import http_errors_total, http_requests_total, ip_rotations_total

log = logging.getLogger("rightmove")

_ua = UserAgent(
    browsers=["Chrome", "Edge"], os=["Windows", "Mac OS X"], min_version=120.0
)


def _endpoint_label(url: str) -> str:
    if "typeahead" in url:
        return "typeahead"
    if "search" in url:
        return "search"
    return "other"


def _status_label(code: int) -> str:
    if code >= 500:
        return "5xx"
    return str(code)


# Gluetun control API — runs on port 8000 inside the gluetun container.
# Since finder uses network_mode: service:gluetun, localhost IS gluetun.
GLUETUN_API = "http://127.0.0.1:8000"
_ip_rotate_lock = threading.Lock()


def rotate_ip() -> bool:
    """Ask gluetun to reconnect to a different VPN server, getting a new IP.
    Returns True if the IP changed successfully."""
    with _ip_rotate_lock:
        log.info("Rotating VPN IP via gluetun...")
        try:
            # Get current IP
            with httpx.Client(timeout=10) as ctl:
                old_ip_resp = ctl.get(f"{GLUETUN_API}/v1/publicip/ip")
                old_ip = (
                    old_ip_resp.json().get("public_ip", "unknown")
                    if old_ip_resp.status_code == 200
                    else "unknown"
                )
                log.info("Current IP: %s", old_ip)

                # Trigger server change — PUT with empty JSON body picks a random server
                resp = ctl.put(
                    f"{GLUETUN_API}/v1/vpn/status", json={"status": "stopped"}
                )
                if resp.status_code != 200:
                    log.error("Failed to stop VPN: %d %s", resp.status_code, resp.text)
                    return False
                time.sleep(2)

                resp = ctl.put(
                    f"{GLUETUN_API}/v1/vpn/status", json={"status": "running"}
                )
                if resp.status_code != 200:
                    log.error("Failed to start VPN: %d %s", resp.status_code, resp.text)
                    return False

            # Wait for reconnection
            for _ in range(30):
                time.sleep(2)
                try:
                    with httpx.Client(timeout=10) as ctl:
                        new_ip_resp = ctl.get(f"{GLUETUN_API}/v1/publicip/ip")
                        if new_ip_resp.status_code == 200:
                            new_ip = new_ip_resp.json().get("public_ip", "")
                            if new_ip and new_ip != old_ip:
                                log.info("IP rotated: %s → %s", old_ip, new_ip)
                                ip_rotations_total.labels(result="success").inc()
                                return True
                except Exception:
                    pass  # VPN still reconnecting

            log.warning("IP rotation timed out (may still be same IP)")
            ip_rotations_total.labels(result="failure").inc()
            return False

        except Exception as e:
            log.error("IP rotation failed: %s", e)
            ip_rotations_total.labels(result="failure").inc()
            return False


def make_client() -> httpx.Client:
    return httpx.Client(
        timeout=30,
        headers={"User-Agent": _ua.random, "Accept": "application/json"},
        follow_redirects=True,
    )


def fetch_with_retry(
    client: httpx.Client, url: str, params: dict | None = None, on_403: bool = True
) -> dict | None:
    """GET JSON with retries on 429/5xx/connection errors. Returns None on permanent failure.
    On 403, triggers IP rotation and retries once."""
    endpoint = _endpoint_label(url)
    for attempt in range(MAX_RETRIES):
        try:
            resp = client.get(url, params=params)
            http_requests_total.labels(
                status=_status_label(resp.status_code), endpoint=endpoint
            ).inc()
            if resp.status_code == 200:
                return resp.json()
            if resp.status_code == 403 and on_403:
                log.warning("HTTP 403 — IP likely blocked, rotating...")
                if rotate_ip():
                    # Retry once with new IP (but don't recurse on 403 again)
                    return fetch_with_retry(client, url, params, on_403=False)
                log.error("IP rotation failed, giving up on %s", url)
                return None
            if resp.status_code in (429, 500, 502, 503, 504):
                delay = RETRY_BASE_DELAY * (2**attempt) + random.uniform(0, 1)
                log.warning(
                    "HTTP %d from %s, retry %d/%d in %.1fs",
                    resp.status_code,
                    url,
                    attempt + 1,
                    MAX_RETRIES,
                    delay,
                )
                time.sleep(delay)
                continue
            log.error("HTTP %d from %s (non-retryable)", resp.status_code, url)
            return None
        except (
            httpx.ConnectError,
            httpx.ReadTimeout,
            httpx.WriteTimeout,
            httpx.PoolTimeout,
        ) as e:
            http_errors_total.labels(type=type(e).__name__).inc()
            delay = RETRY_BASE_DELAY * (2**attempt) + random.uniform(0, 1)
            log.warning(
                "%s from %s, retry %d/%d in %.1fs",
                type(e).__name__,
                url,
                attempt + 1,
                MAX_RETRIES,
                delay,
            )
            time.sleep(delay)
    http_errors_total.labels(type="retry_exhausted").inc()
    log.error("All %d retries exhausted for %s", MAX_RETRIES, url)
    return None