fix: Adjust the Cron process in general and include it inside supervisord

README.md

@@ -7,7 +7,7 @@ You can execute `docker-compose up -d --build --force-recreate` to start and bui
 
 ### Cronjobs
 
-It is possible to adapt the `pretixuser` crontab entries by modifying the [crontab.bak](docker/pretix/crontab.bak) file.
+It is possible to adapt the `pretixuser` crontab entries by modifying the [crontab](docker/pretix/crontab.bak) file.
 
 ## Contribution
 If you would like to contribute something, have an improvement request, or want to make a change inside the code, please open a pull request.

docker-compose.yml

@@ -12,6 +12,7 @@ services:
     volumes:
       - pretix_data:/data
       - ./docker/pretix/pretix.cfg:/etc/pretix/pretix.cfg
+      - ./docker/pretix/crontab:/tmp/crontab
     ports:
       - "8000:80"
     networks:

docker/pretix/Dockerfile

@@ -2,13 +2,15 @@ FROM pretix/standalone:stable
 
 USER root
 
-RUN apt update && apt install cron nano -y
+ENV IMAGE_CRON_DIR="/image/cron"
 
-USER pretixuser
+ADD files /image
+COPY crontab /tmp/crontab
+
+RUN mv /image/supervisord/crond.conf /etc/supervisord/crond.conf && \
+    pip install crontab && chmod +x $IMAGE_CRON_DIR/cron.py
 
-COPY crontab.bak /tmp/crontab.bak
-RUN crontab /tmp/crontab.bak
+USER pretixuser
 
-EXPOSE 80
 ENTRYPOINT ["pretix"]
 CMD ["all"]

docker/pretix/crontab.bak → docker/pretix/crontab

@@ -21,4 +21,4 @@
 # For more information see the manual pages of crontab(5) and cron(8)
 #
 # m h  dom mon dow   command
-15,45 * * * * PRETIX_CONFIG_FILE=/etc/pretix/pretix.cfg python -m pretix runperiodic
+15,45 * * * * su pretixuser -c "PRETIX_CONFIG_FILE=/etc/pretix/pretix.cfg python -m pretix runperiodic"

docker/pretix/files/cron/cron.py

@@ -0,0 +1,224 @@
+#!/usr/local/bin/python3
+
+from crontab import CronTab
+import argparse
+import logging
+import time
+import subprocess
+import sys
+import signal
+import os
+
+
+def _parse_crontab(crontab_file: str) -> list:
+    """The method includes a functionality to parse the crontab file, and it returns a list of CronTab jobs
+
+    Keyword arguments:
+    crontab_file -> Specify the inserted crontab file
+    """
+
+    logger = logging.getLogger("parser")
+
+    logger.info(f"Reading crontab from {crontab_file}")
+
+    if not os.path.isfile(crontab_file):
+        logger.error(f"Crontab {crontab_file} does not exist. Exiting!")
+        sys.exit(1)
+
+    with open(crontab_file, "r") as crontab:
+        lines: list = crontab.readlines()
+
+    logger.info(f"{len(lines)} lines read from crontab {crontab_file}")
+
+    jobs: list = list()
+
+    for i, line in enumerate(lines):
+        line: str = line.strip()
+
+        if not line:
+            continue
+
+        if line.startswith("#"):
+            continue
+
+        logger.info(f"Parsing line {line}")
+
+        expression: list = line.split(" ", 5)
+        cron_expression: str = " ".join(expression[0:5])
+
+        logger.info(f"Cron expression is {cron_expression}")
+
+        try:
+            cron_entry = CronTab(cron_expression)
+        except ValueError as e:
+            logger.critical(
+                f"Unable to parse crontab. Line {i + 1}: Illegal cron expression {cron_expression}. Error message: {e}"
+            )
+            sys.exit(1)
+
+        command: str = expression[5]
+
+        logger.info(f"Command is {command}")
+
+        jobs.append([cron_entry, command])
+
+    if len(jobs) == 0:
+        logger.error(
+            "Specified crontab does not contain any scheduled execution. Exiting!"
+        )
+        sys.exit(1)
+
+    return jobs
+
+
+def _get_next_executions(jobs: list):
+    """The method includes a functionality to extract the execution time and job itself from the submitted job list
+
+    Keyword arguments:
+    jobs -> Specify the inserted list of jobs
+    """
+
+    logger = logging.getLogger("next-exec")
+
+    scheduled_executions: tuple = tuple(
+        (x[1], int(x[0].next(default_utc=True)) + 1) for x in jobs
+    )
+
+    logger.debug(f"Next executions of scheduled are {scheduled_executions}")
+
+    next_exec_time: int = int(min(scheduled_executions, key=lambda x: x[1])[1])
+
+    logger.debug(f"Next execution is in {next_exec_time} second(s)")
+
+    next_commands: list = [x[0] for x in scheduled_executions if x[1] == next_exec_time]
+
+    logger.debug(
+        f"Next commands to be executed  in {next_exec_time} are {next_commands}"
+    )
+
+    return next_exec_time, next_commands
+
+
+def _loop(jobs: list, test_mode: bool = False):
+    """The method includes a functionality to loop over all jobs inside the crontab file and execute them
+
+    Keyword arguments:
+    jobs -> Specify the inserted jobs as list
+    test_mode -> Specify if you want to use the test mode or not (default False)
+    """
+
+    logger = logging.getLogger("loop")
+
+    logger.info("Entering main loop")
+
+    if test_mode is False:
+        while True:
+            sleep_time, commands = _get_next_executions(jobs)
+
+            logger.debug(f"Sleeping for {sleep_time} second(s)")
+
+            if sleep_time <= 1:
+                logger.debug("Sleep time <= 1 second, ignoring.")
+                time.sleep(1)
+                continue
+
+            time.sleep(sleep_time)
+
+            for command in commands:
+                _execute_command(command)
+    else:
+        sleep_time, commands = _get_next_executions(jobs)
+
+        logger.debug(f"Sleeping for {sleep_time} second(s)")
+
+        if sleep_time <= 1:
+            logger.debug("Sleep time <= 1 second, ignoring.")
+            time.sleep(1)
+
+        time.sleep(sleep_time)
+
+        for command in commands:
+            _execute_command(command)
+
+
+def _execute_command(command: str):
+    """The method includes a functionality to execute a crontab command
+
+    Keyword arguments:
+    command -> Specify the inserted command for the execution
+    """
+
+    logger = logging.getLogger("exec")
+
+    logger.info(f"Executing command {command}")
+
+    result = subprocess.run(
+        command, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True
+    )
+
+    logger.info(f"Standard output: {result.stdout}")
+    logger.info(f"Standard error: {result.stderr}")
+
+
+def _signal_handler():
+    """The method includes a functionality for the signal handler to exit a process"""
+
+    logger = logging.getLogger("signal")
+    logger.info("Exiting")
+    sys.exit(0)
+
+
+def main():
+    """The method includes a functionality to control and execute crontab entries
+
+    Arguments:
+    -c -> Specify the inserted crontab file
+    -L -> Specify the inserted log file
+    -C -> Specify the if the output should be forwarded to the console
+    -l -> Specify the log level
+    """
+    signal.signal(signal.SIGINT, _signal_handler)
+    signal.signal(signal.SIGTERM, _signal_handler)
+
+    parser = argparse.ArgumentParser(description="cron")
+    parser.add_argument("-c", "--crontab", required=True, type=str)
+    logging_target = parser.add_mutually_exclusive_group(required=True)
+    logging_target.add_argument("-L", "--logfile", type=str)
+    logging_target.add_argument("-C", "--console", action="store_true")
+    parser.add_argument(
+        "-l",
+        "--loglevel",
+        choices=["DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"],
+        default="INFO",
+        type=str,
+    )
+
+    args = parser.parse_args()
+
+    log_level = getattr(logging, args.loglevel.upper(), logging.INFO)
+
+    if args.console:
+        logging.basicConfig(
+            filemode="w",
+            level=log_level,
+            format="%(asctime)s %(name)-12s %(levelname)-8s %(message)s",
+        )
+    else:
+        logging.basicConfig(
+            filename=args.logfile,
+            filemode="a+",
+            level=log_level,
+            format="%(asctime)s %(name)-12s %(levelname)-8s %(message)s",
+        )
+
+    logger = logging.getLogger("main")
+
+    logger.info("Starting cron")
+
+    jobs: list = _parse_crontab(args.crontab)
+
+    _loop(jobs)
+
+
+if __name__ == "__main__":
+    main()

docker/pretix/files/supervisord/crond.conf

@@ -0,0 +1,7 @@
+[program:crond]
+command = %(ENV_IMAGE_CRON_DIR)s/cron.py --crontab /tmp/crontab --loglevel INFO --logfile /var/log/crond.log
+autostart = true
+redirect_stderr = true
+stdout_logfile = /var/log/crond.log
+stdout_logfile_maxbytes = 1MB
+stdout_logfile_backups = 2