David Culbreth
f3c159913e
Includes: - 3 Python actions (hello, http_example, read_counter) - 1 counter trigger type - 1 counter sensor (Python, keystore-backed, per-rule state) - 1 example rule (count_and_log) - requirements.txt with requests and pika - README with full usage documentation
541 lines
18 KiB
Python
541 lines
18 KiB
Python
#!/usr/bin/env python3
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"""
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Counter Sensor - Python Example Pack
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A stateful Python sensor that demonstrates:
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- RabbitMQ integration for rule lifecycle events
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- Attune keystore API for persistent per-rule counter state
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- Periodic event emission via the Attune events API
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- Per-rule scoped counters with independent timer threads
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- Graceful shutdown with thread cleanup
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Environment Variables (provided by attune-sensor service):
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ATTUNE_API_URL - Base URL of the Attune API (e.g. http://localhost:8080)
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ATTUNE_API_TOKEN - JWT token for authenticating API calls
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ATTUNE_SENSOR_ID - Database ID of this sensor instance
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ATTUNE_SENSOR_REF - Reference name (python_example.counter_sensor)
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ATTUNE_MQ_URL - RabbitMQ connection URL (e.g. amqp://localhost:5672)
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ATTUNE_MQ_EXCHANGE - RabbitMQ exchange name (default: attune)
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ATTUNE_LOG_LEVEL - Logging verbosity (default: info)
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"""
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import json
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import logging
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import os
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import signal
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import sys
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import threading
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import time
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from datetime import datetime, timezone
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import pika
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import requests
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# ---------------------------------------------------------------------------
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# Configuration
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# ---------------------------------------------------------------------------
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API_URL = os.environ.get("ATTUNE_API_URL", "http://localhost:8080")
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API_TOKEN = os.environ.get("ATTUNE_API_TOKEN", "")
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SENSOR_ID = os.environ.get("ATTUNE_SENSOR_ID", "0")
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SENSOR_REF = os.environ.get("ATTUNE_SENSOR_REF", "python_example.counter_sensor")
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MQ_URL = os.environ.get("ATTUNE_MQ_URL", "amqp://localhost:5672")
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MQ_EXCHANGE = os.environ.get("ATTUNE_MQ_EXCHANGE", "attune")
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LOG_LEVEL = os.environ.get("ATTUNE_LOG_LEVEL", "info").upper()
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TRIGGER_TYPE = "python_example.counter"
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KEY_PREFIX = "python_example.counter"
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DEFAULT_INTERVAL = 1 # seconds
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# ---------------------------------------------------------------------------
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# Logging
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# ---------------------------------------------------------------------------
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logging.basicConfig(
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level=getattr(logging, LOG_LEVEL, logging.INFO),
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format="%(message)s",
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stream=sys.stderr,
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)
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logger = logging.getLogger("counter_sensor")
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def log_json(level, message, **extra):
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"""Emit a structured JSON log line to stderr."""
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entry = {
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"timestamp": datetime.now(timezone.utc).isoformat(),
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"level": level,
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"sensor": SENSOR_REF,
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"message": message,
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**extra,
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}
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print(json.dumps(entry), file=sys.stderr, flush=True)
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# ---------------------------------------------------------------------------
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# API helpers
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# ---------------------------------------------------------------------------
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def _api_headers():
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return {
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"Authorization": f"Bearer {API_TOKEN}",
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"Content-Type": "application/json",
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}
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def keystore_get(key_ref):
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"""Read a key from the Attune keystore. Returns the value or None."""
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try:
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resp = requests.get(
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f"{API_URL}/api/v1/keys/{key_ref}",
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headers=_api_headers(),
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timeout=5,
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)
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if resp.status_code == 200:
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data = resp.json().get("data", {})
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return data.get("value")
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if resp.status_code == 404:
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return None
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log_json(
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"warn",
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"keystore GET unexpected status",
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key=key_ref,
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status=resp.status_code,
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)
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return None
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except requests.RequestException as exc:
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log_json("error", "keystore GET failed", key=key_ref, error=str(exc))
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return None
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def keystore_put(key_ref, value):
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"""Update an existing key in the Attune keystore."""
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try:
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resp = requests.put(
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f"{API_URL}/api/v1/keys/{key_ref}",
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headers=_api_headers(),
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json={"value": str(value), "name": f"Counter: {key_ref}"},
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timeout=5,
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)
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if resp.status_code not in (200, 201):
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log_json(
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"warn",
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"keystore PUT unexpected status",
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key=key_ref,
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status=resp.status_code,
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)
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return resp.status_code in (200, 201)
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except requests.RequestException as exc:
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log_json("error", "keystore PUT failed", key=key_ref, error=str(exc))
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return False
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def keystore_create(key_ref, value, rule_ref):
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"""Create a new key in the Attune keystore."""
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try:
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resp = requests.post(
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f"{API_URL}/api/v1/keys",
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headers=_api_headers(),
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json={
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"ref": key_ref,
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"owner_type": "sensor",
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"owner_sensor_ref": SENSOR_REF,
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"name": f"Counter: {key_ref}",
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"value": str(value),
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"encrypted": False,
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},
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timeout=5,
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)
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if resp.status_code in (200, 201):
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return True
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if resp.status_code == 409:
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# Key already exists (race condition) — update instead
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return keystore_put(key_ref, value)
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log_json(
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"warn",
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"keystore POST unexpected status",
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key=key_ref,
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status=resp.status_code,
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)
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return False
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except requests.RequestException as exc:
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log_json("error", "keystore POST failed", key=key_ref, error=str(exc))
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return False
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def emit_event(payload, rule_ref):
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"""Create an event via POST /events."""
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body = {
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"trigger_type": TRIGGER_TYPE,
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"payload": payload,
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"trigger_instance_id": f"rule_{rule_ref}",
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}
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for attempt in range(3):
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try:
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resp = requests.post(
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f"{API_URL}/api/v1/events",
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headers=_api_headers(),
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json=body,
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timeout=5,
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)
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if resp.status_code in (200, 201):
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return True
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log_json(
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"warn",
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"event POST unexpected status",
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status=resp.status_code,
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attempt=attempt + 1,
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rule_ref=rule_ref,
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)
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except requests.RequestException as exc:
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log_json("error", "event POST failed", error=str(exc), attempt=attempt + 1)
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# Exponential backoff
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time.sleep(0.5 * (2**attempt))
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return False
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# ---------------------------------------------------------------------------
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# Per-rule counter loop
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# ---------------------------------------------------------------------------
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class RuleCounter:
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"""Manages a per-rule counter with a background timer thread."""
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def __init__(self, rule_id, rule_ref, trigger_params):
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self.rule_id = rule_id
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self.rule_ref = rule_ref
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self.interval = trigger_params.get("interval_seconds", DEFAULT_INTERVAL)
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self.key_ref = f"{KEY_PREFIX}.{rule_ref.replace('.', '_')}"
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self._stop = threading.Event()
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self._thread = None
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def start(self):
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"""Start the counter loop in a background thread."""
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if self._thread is not None and self._thread.is_alive():
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return
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self._stop.clear()
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self._thread = threading.Thread(
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target=self._loop,
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name=f"counter-{self.rule_ref}",
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daemon=True,
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)
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self._thread.start()
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log_json(
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"info",
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"counter started",
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rule_id=self.rule_id,
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rule_ref=self.rule_ref,
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interval=self.interval,
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)
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def stop(self):
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"""Signal the counter loop to stop and wait for it."""
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self._stop.set()
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if self._thread is not None:
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self._thread.join(timeout=5)
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self._thread = None
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log_json(
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"info", "counter stopped", rule_id=self.rule_id, rule_ref=self.rule_ref
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)
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def _loop(self):
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"""Main counter loop: read → increment → write → emit, repeat."""
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while not self._stop.is_set():
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try:
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self._tick()
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except Exception as exc:
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log_json(
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"error",
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"counter tick failed",
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rule_ref=self.rule_ref,
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error=str(exc),
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)
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self._stop.wait(timeout=self.interval)
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def _tick(self):
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"""Execute one counter cycle."""
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# Read current value from keystore
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raw = keystore_get(self.key_ref)
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if raw is not None:
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try:
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counter = int(raw)
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except (ValueError, TypeError):
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counter = 0
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else:
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counter = 0
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# Increment
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counter += 1
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# Write back to keystore
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if raw is None:
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keystore_create(self.key_ref, counter, self.rule_ref)
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else:
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keystore_put(self.key_ref, counter)
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# Build event payload
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payload = {
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"counter": counter,
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"rule_ref": self.rule_ref,
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"sensor_ref": SENSOR_REF,
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"fired_at": datetime.now(timezone.utc).isoformat(),
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}
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# Emit event
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emit_event(payload, self.rule_ref)
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# ---------------------------------------------------------------------------
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# Rule manager
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# ---------------------------------------------------------------------------
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class RuleManager:
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"""Tracks active rules and their counter threads."""
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def __init__(self):
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self._rules = {} # rule_id -> RuleCounter
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self._lock = threading.Lock()
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def handle_message(self, message):
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"""Process a rule lifecycle message from RabbitMQ."""
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event_type = message.get("event_type", "")
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rule_id = message.get("rule_id")
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rule_ref = message.get("rule_ref", f"rule_{rule_id}")
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trigger_type = message.get("trigger_type", "")
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trigger_params = message.get("trigger_params", {})
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# Only handle messages for our trigger type
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if trigger_type and trigger_type != TRIGGER_TYPE:
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return
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if event_type in ("RuleCreated", "RuleEnabled"):
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self._start_rule(rule_id, rule_ref, trigger_params)
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elif event_type in ("RuleDisabled", "RuleDeleted"):
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self._stop_rule(rule_id)
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else:
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log_json("debug", "ignoring unknown event_type", event_type=event_type)
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def _start_rule(self, rule_id, rule_ref, trigger_params):
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with self._lock:
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if rule_id in self._rules:
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# Already tracking — restart with potentially new params
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self._rules[rule_id].stop()
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rc = RuleCounter(rule_id, rule_ref, trigger_params)
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self._rules[rule_id] = rc
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rc.start()
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def _stop_rule(self, rule_id):
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with self._lock:
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rc = self._rules.pop(rule_id, None)
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if rc is not None:
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rc.stop()
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def stop_all(self):
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"""Stop all active counter threads."""
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with self._lock:
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rule_ids = list(self._rules.keys())
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for rid in rule_ids:
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self._stop_rule(rid)
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@property
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def active_count(self):
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with self._lock:
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return len(self._rules)
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# ---------------------------------------------------------------------------
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# RabbitMQ consumer
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# ---------------------------------------------------------------------------
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ROUTING_KEYS = ["rule.created", "rule.enabled", "rule.disabled", "rule.deleted"]
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def start_mq_consumer(rule_manager, shutdown_event):
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"""Connect to RabbitMQ and consume rule lifecycle messages.
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Runs in a dedicated thread. Reconnects automatically on failure.
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"""
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queue_name = f"sensor.{SENSOR_REF}"
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while not shutdown_event.is_set():
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connection = None
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try:
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log_json("info", "connecting to RabbitMQ", url=MQ_URL)
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params = pika.URLParameters(MQ_URL)
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params.heartbeat = 30
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params.blocked_connection_timeout = 30
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connection = pika.BlockingConnection(params)
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channel = connection.channel()
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# Declare exchange (idempotent)
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channel.exchange_declare(
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exchange=MQ_EXCHANGE,
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exchange_type="topic",
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durable=True,
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)
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# Declare and bind queue
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channel.queue_declare(queue=queue_name, durable=True)
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for rk in ROUTING_KEYS:
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channel.queue_bind(
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queue=queue_name,
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exchange=MQ_EXCHANGE,
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routing_key=rk,
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)
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log_json("info", "RabbitMQ connected, consuming", queue=queue_name)
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# Consume messages with a timeout so we can check shutdown_event
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for method, _properties, body in channel.consume(
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queue=queue_name,
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inactivity_timeout=1,
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):
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if shutdown_event.is_set():
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break
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if method is None:
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# Inactivity timeout — just loop to check shutdown
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continue
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try:
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message = json.loads(body)
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log_json(
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"debug",
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"received MQ message",
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event_type=message.get("event_type"),
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)
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rule_manager.handle_message(message)
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except json.JSONDecodeError:
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log_json(
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"warn",
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"invalid JSON in MQ message",
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body=body.decode("utf-8", errors="replace")[:200],
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)
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except Exception as exc:
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log_json("error", "error processing MQ message", error=str(exc))
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channel.basic_ack(delivery_tag=method.delivery_tag)
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except pika.exceptions.AMQPConnectionError as exc:
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log_json(
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"warn", "RabbitMQ connection error, retrying in 5s", error=str(exc)
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)
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except Exception as exc:
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log_json("error", "unexpected MQ error, retrying in 5s", error=str(exc))
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finally:
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if connection and not connection.is_closed:
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try:
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connection.close()
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except Exception:
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pass
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# Wait before reconnecting (unless shutting down)
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shutdown_event.wait(timeout=5)
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# ---------------------------------------------------------------------------
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# Bootstrap: fetch existing active rules on startup
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# ---------------------------------------------------------------------------
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def fetch_active_rules(rule_manager):
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"""Query the API for rules that reference our trigger type and start counters."""
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try:
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resp = requests.get(
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f"{API_URL}/api/v1/rules",
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headers=_api_headers(),
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params={"trigger_ref": TRIGGER_TYPE, "enabled": "true"},
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timeout=10,
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)
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if resp.status_code != 200:
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log_json("warn", "failed to fetch active rules", status=resp.status_code)
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return
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body = resp.json()
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rules = body.get("data", [])
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if not isinstance(rules, list):
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# Might be paginated — handle the common shapes
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rules = []
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for rule in rules:
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rule_id = rule.get("id")
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rule_ref = rule.get("ref", f"rule_{rule_id}")
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enabled = rule.get("enabled", True)
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if rule_id and enabled:
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rule_manager.handle_message(
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{
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"event_type": "RuleCreated",
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"rule_id": rule_id,
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"rule_ref": rule_ref,
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"trigger_type": TRIGGER_TYPE,
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"trigger_params": rule.get("trigger_params", {}),
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}
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)
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log_json("info", "bootstrapped active rules", count=len(rules))
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except requests.RequestException as exc:
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log_json("warn", "could not fetch active rules on startup", error=str(exc))
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|
|
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# ---------------------------------------------------------------------------
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# Main
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# ---------------------------------------------------------------------------
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def main():
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log_json("info", "sensor starting", sensor_ref=SENSOR_REF, api_url=API_URL)
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shutdown_event = threading.Event()
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rule_manager = RuleManager()
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# Handle termination signals
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def _shutdown(signum, _frame):
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sig_name = (
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signal.Signals(signum).name if hasattr(signal, "Signals") else str(signum)
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)
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log_json("info", "shutdown signal received", signal=sig_name)
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shutdown_event.set()
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signal.signal(signal.SIGTERM, _shutdown)
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signal.signal(signal.SIGINT, _shutdown)
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# Bootstrap: load already-active rules from the API
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fetch_active_rules(rule_manager)
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# Start RabbitMQ consumer in a background thread
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mq_thread = threading.Thread(
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target=start_mq_consumer,
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args=(rule_manager, shutdown_event),
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name="mq-consumer",
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daemon=True,
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)
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mq_thread.start()
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log_json("info", "sensor running", active_rules=rule_manager.active_count)
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# Main thread just waits for shutdown
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try:
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while not shutdown_event.is_set():
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shutdown_event.wait(timeout=10)
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if not shutdown_event.is_set():
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log_json("debug", "heartbeat", active_rules=rule_manager.active_count)
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except KeyboardInterrupt:
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log_json("info", "keyboard interrupt")
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shutdown_event.set()
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# Graceful shutdown
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log_json("info", "shutting down", active_rules=rule_manager.active_count)
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rule_manager.stop_all()
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|
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# Give the MQ thread a moment to clean up
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mq_thread.join(timeout=5)
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|
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log_json("info", "sensor stopped")
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|
|
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if __name__ == "__main__":
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main()
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