web_monitor_agent.py

#!/usr/bin/env python3

"""Monitors the health of several Web pages, collecting the information listed below,
and publishes (Producer) it to a Kafka topic:
* HTTP response time
* Error code returned
* Pattern that is expected to be found on the page 
"""

# import daemon
import sys
from homeworks import config
from homeworks import logging_console
from homeworks.get_request_thread import Get_request_thread

log = logging_console.getLogger("homeworks")


def waitting_threads_ending_loop(threads: list[Get_request_thread]):
    """Wait for threads to end, however these threads stop only
    when they're killed; therefore process becomes a daemon and
    it runs for always

    Args:
        urls (list[Get_request_thread]): List of threads waiting to end
    """
    for thread in threads:
        thread.join()

    log.warning("All threads stopped by themselves")


def main() -> int:
    """Main program

    Returns:
        int: Return 0 if all ran without issues (Note: Ctrl+break is considered a normal way to stop it and it should exit with 0)
    """
    result = 1
    threads = []
    slice = 5  # Max. number of URLs managed by a thread
    try:
        for i in range(0, len(config.monitored_url_targets), slice):
            """From total list of URLs, it is splitted in slices
            of 5 URLs (max.). One individual thread is created for
            monitoring every slice
            """
            urls = config.monitored_url_targets[i : i + slice]
            log.debug(f"Creating Thread for URLs: {urls}")
            thread = Get_request_thread(urls)
            thread.daemon = True  # Daemons are killed when the main program exits
            thread.start()
            threads.append(thread)

        # TODO: URGENT! Run next call under 'daemon.DaemonContext()' context, following specifications PEP 3143
        waitting_threads_ending_loop(threads)
    except KeyboardInterrupt:
        result = 0
        log.info("Keyboard interruption received (Ctrl+break)")
    except Exception:
        log.exception("Unexpected error")
    else:
        result = 0
    finally:
        return result


if __name__ == "__main__":
    logging_console.init_logging()
    result = 255
    result = main()

    sys.exit(result)