[Python] cronjob hour setting is being ignored in docker alpine container

I created a script called 'main.py' that does a little web scrape and sends an e-mail with SMTP. I set up a cron job to run the script three times a day - at 12:00, 18:00 and 21:00 (UTC-3). I didn't changed the docker image's tz so it runs in UTC0.

Here's the cron job I added:

0 15,21,24 \* \* \* python /app/main.py \>\> /var/log/cron.log 2\>&1

However, the script main.py is being called every hour, respecting only the minutes field in the cron job (for example, if i change to

0,15,20 15,21,24 \* \* \* python /app/main.py \>\> /var/log/cron.log 2\>&1

it runs hourly, at minutes 0, 15 and 20 minutes.

Bellow is my .sh script for the container to run

#!/bin/bash

set -e

echo "Starting Xvfb..."
Xvfb :99 -screen 0 1280x1024x24 -nolisten tcp -ac &

sleep 3

echo 'starting cron'
crond -f -l 8 &

tail -f /var/log/cron.log


And here is my dockerfile:

FROM python:3.11-alpine

ENV DISPLAY=:99
WORKDIR /app
COPY . /app


COPY cron_job /etc/crontabs/root


RUN touch /var/log/cron.log

RUN apk update && \
apk add \
gcc \
g++ \
musl-dev \
libffi-dev \
make \
libc++ \
libc++-dev \
&& apk add --virtual .build-deps gcc g++ make musl-dev

RUN apk update && \
apk add \
firefox \
dbus \
ttf-freefont \
xorg-server \
xf86-video-vesa \
bash \
curl \
unzip \
xvfb-run \
su-exec \
libjpeg \
libpng


RUN apk add --no-cache bash curl busybox-suid && \
chmod u+s /bin/busybox


RUN wget https://github.com/mozilla/geckodriver/releases/download/v0.36.0/geckodriver-v0.36.0-linux64.tar.gz
RUN tar -xzf geckodriver-v0.36.0-linux64.tar.gz
RUN mv geckodriver /usr/local/bin/geckodriver
RUN chmod +x /usr/local/bin/geckodriver

RUN pip install --upgrade pip && \
pip install -r requirements.txt

RUN chmod +x shebang.sh
CMD \["./script.sh"\]

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