Cron does not run in a PHP Docker container

Question

I am using the php:7.4-fpm Docker image and I'm trying to set up cron to run but it's not running.

Here is my Dockerfile:

FROM php:7.4-fpm

# Set working directory
WORKDIR /var/www

# Install dependencies
RUN apt-get update && apt-get install -y \
    cron \
    build-essential \
    libpng-dev \
    libjpeg62-turbo-dev \
    libfreetype6-dev \
    locales \
    libzip-dev \
    libmcrypt-dev \
    libonig-dev \
    zlib1g-dev \
    zip \
    jpegoptim optipng pngquant gifsicle \
    vim \
    unzip \
    git \
    graphviz \
    curl \
    supervisor

# Install Imagick
RUN apt-get update && \
    apt-get install -y libmagickwand-dev --no-install-recommends && \
    pecl install imagick && \
    docker-php-ext-enable imagick

# Clear cache
RUN apt-get clean && rm -rf /var/lib/apt/lists/*

# Install extensions
RUN docker-php-ext-install pdo_mysql zip exif pcntl

# Permissions for Laravel
RUN chown -R www-data:www-data /var/www
RUN chmod -R 777 /var/www

# Copy crontab file to the cron.d directory
COPY ./docker/php-server/crontab /etc/cron.d/crontab

# Give execution rights on the cron job
RUN chmod 0644 /etc/cron.d/crontab

# Apply cron job
RUN crontab /etc/cron.d/crontab

# Create the log file to be able to run tail
RUN touch /var/log/cron.log

EXPOSE 9000

CMD bash -c "cron && php-fpm"

When I enter the container and check the contents of /etc/cron.d/crontab it is correct

* * * * * php /var/www/artisan schedule:run >> /var/log/cron.log 2>&1
# An empty line

But it's not being run. I'm not sure what's going on here..

When I run service cron status it says [ ok ] cron is running. But nothing is happening.

Answer 1

So I finally managed to solve it. I have no idea why COPYing the cron file wasn't working. I still don't know why. (maybe someone smarter than me can explain it). But I solved it very simply by appending my commands to the /etc/crontab file and now it works.

P.S. crontab file requires a new line character at the end so using echo adds it automatically.

Here is my updated Dockerfile (I deleted all the other lines where I copied the crontab):

RUN echo "* * * * * root php /var/www/artisan schedule:run >> /var/log/cron.log 2>&1" >> /etc/crontab

# Create the log file to be able to run tail
RUN touch /var/log/cron.log