How to set sendmail_path config for PHP-FPM in docker?

Question

PHP

Puff is spinning in the docker.
Here is the Dockerfile:

FROM php:5.6.35-fpm

RUN apt-get update && apt-get install -y \
      curl \
      wget \
      git \
      nano \
      mc \
      htop \
      net-tools \
      iputils-ping \
      libfreetype6-dev \
      libjpeg62-turbo-dev \
      libmcrypt-dev \
      libpng12-dev \
      libpq-dev \
      libxml2-dev \
      g++ \
            libicu-dev \
            zlib1g-dev \
            libxslt-dev \
            zip \
        && pecl install xdebug-2.5.5 \
        && docker-php-ext-enable xdebug \
    && docker-php-ext-install -j$(nproc) iconv mcrypt mbstring mysqli pdo_mysql zip \
    && docker-php-ext-configure gd --with-freetype-dir=/usr/include/ --with-jpeg-dir=/usr/include/ \
    && docker-php-ext-install -j$(nproc) gd \
    && docker-php-ext-install -j$(nproc) pgsql \
    && docker-php-ext-install -j$(nproc) pdo_pgsql \
    && docker-php-ext-install -j$(nproc) soap \
    && docker-php-ext-install -j$(nproc) bcmath \
        && curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer

COPY docker-entrypoint.sh /usr/local/bin/
COPY mailtodisk /usr/local/bin

ADD php.ini /usr/local/etc/php/conf.d/40-custom.ini

WORKDIR /var/www

CMD ["/usr/local/bin/docker-entrypoint.sh"]

Here is my entrypoint script:

#!/bin/sh
groupmod -g $(stat -c '%g' /var/www) www-data
usermod -u $(stat -c '%u' /var/www) www-data
HOST_DOMAIN="host.docker.internal"
ping -q -c1 $HOST_DOMAIN > /dev/null 2>&1
if [ $? -ne 0 ]; then
  HOST_IP=$(ip route | awk 'NR==1 {print $3}')
  echo "$HOST_IP\t$HOST_DOMAIN" >> /etc/hosts
fi
php-fpm

And here, in fact, php.ini itself (which flies into the container):

php_admin_value[sendmail_path] = /usr/local/bin/mailtodisk
php_admin_value[error_log] = /var/log/fpm-php.www.log
php_admin_flag[log_errors] = on
xdebug.remote_enable=1
xdebug.remote_port=9000
xdebug.remote_autostart=1
xdebug.remote_connect_back=0
xdebug.idekey=PHPSTORM
xdebug.remote_host=host.docker.internal

Problem: sendmail_path is ignored, it does not reach the specified script. Nothing falls into the log, there are no assumptions.

Answer 1

Understood. Moved sendmail_path to a separate config, and at the very beginning added the pool name, something like this:
[www]
php_admin_value[sendmail_path] = /usr/local/bin/mailtodisk