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66 lines
2.7 KiB
Python
66 lines
2.7 KiB
Python
import logging
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from datetime import datetime
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from threading import Thread, Event
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import pytz
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import requests
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from alertproviders.alert_provider import AlertProvider
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from core.constants import HTTP_HEADERS
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class HTTPAlertProvider(AlertProvider):
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"""Generic alert provider class for providers that request data via HTTP(S). Just for convenience to avoid code
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duplication. Subclasses of this query the individual APIs for data."""
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def __init__(self, provider_config, url, poll_interval):
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super().__init__(provider_config)
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self._url = url
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self._poll_interval = poll_interval
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self._thread = None
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self._stop_event = Event()
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def start(self):
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# Fire off the polling thread. It will poll immediately on startup, then sleep for poll_interval between
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# subsequent polls, so start() returns immediately and the application can continue starting.
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logging.info("Set up query of " + self.name + " alert API every " + str(self._poll_interval) + " seconds.")
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self._thread = Thread(target=self._run, daemon=True)
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self._thread.start()
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def stop(self):
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self._stop_event.set()
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def _run(self):
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while True:
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self._poll()
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if self._stop_event.wait(timeout=self._poll_interval):
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break
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def _poll(self):
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try:
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# Request data from API
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logging.debug("Polling " + self.name + " alert API...")
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http_response = requests.get(self._url, headers=HTTP_HEADERS)
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# Pass off to the subclass for processing
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new_alerts = self._http_response_to_alerts(http_response)
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# Submit the new alerts for processing. There might not be any alerts for the less popular programs.
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if new_alerts:
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self._submit_batch(new_alerts)
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self.status = "OK"
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self.last_update_time = datetime.now(pytz.UTC)
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logging.debug("Received data from " + self.name + " alert API.")
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except Exception:
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self.status = "Error"
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logging.exception("Exception in HTTP JSON Alert Provider (" + self.name + ")")
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# Brief pause on error before the next poll, but still respond promptly to stop()
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self._stop_event.wait(timeout=1)
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def _http_response_to_alerts(self, http_response):
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"""Convert an HTTP response returned by the API into alert data. The whole response is provided here so the subclass
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implementations can check for HTTP status codes if necessary, and handle the response as JSON, XML, text, whatever
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the API actually provides."""
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raise NotImplementedError("Subclasses must implement this method")
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