Why won't mysql start in a docker container?

Question

MariaDB

Hello!

Here is the content of my Dockerfile. Its task is to deploy apache + php + mariadb (and yes, I need the database to be in this container).

FROM php:7.3-apache

RUN apt-get update -y && apt-get install -y \
  curl \
  wget \
  git \
  libfreetype6-dev \
  libjpeg62-turbo-dev \
  libmcrypt-dev \
  libzip-dev \
  libxml2 libxml2-dev \
    && docker-php-ext-install iconv \
    && docker-php-ext-install mbstring \
    && docker-php-ext-install mysqli \
    && docker-php-ext-install pdo_mysql \
    && docker-php-ext-install gd \
    && docker-php-ext-install -j$(nproc) gd \
    && docker-php-ext-install zip \
    && docker-php-ext-install opcache \
    && docker-php-ext-install soap

RUN echo "\
  short_open_tag = On\n\
  display_errors = On\n\
  error_log = /var/log/php/error.log\n\
  error_reporting = E_ALL ^ E_DEPRECATED\n\
  log_errors = On\n\
  display_startup_errors = On\n\
  cgi.fix_pathinfo = 0\n\
  date.timezone = Europe/Moscow\n\
  mbstring.func_overload = 2\n\
  mbstring.internal_encoding = UTF-8\n\
  max_input_vars = 10000\n\
  post_max_size = 1024M\n\
  memory_limit = 512M\n\
  upload_max_filesize = 1024M\n\
  max_execution_time=60\n\
  extension=mcrypt" > /usr/local/etc/php/php.ini

RUN a2enmod rewrite

RUN ln -sf /dev/stdout /var/log/apache2/access.log \
    && ln -sf /dev/stderr /var/log/apache2/error.log

RUN groupadd -r mysql && useradd -r -g mysql mysql

RUN apt-get install -y mariadb-server mariadb-client

RUN /etc/init.d/mysql start && \
        mysql -u root -e "CREATE DATABASE web"

RUN mkdir /root/.ssh/
ADD id_rsa /root/.ssh/id_rsa
RUN touch /root/.ssh/known_hosts
RUN ssh-keyscan bitbucket.org >> /root/.ssh/known_hosts

EXPOSE 80 443

CMD ["/etc/init.d/mysql",  "start"]
CMD ["apachectl", "-DFOREGROUND"]

The problem is that mysql does not start when the container starts, although the database is created.
When the application tries to connect to the mysql server, we get an error:

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

Please tell me where to dig?