Install PHP Memcache in docker php

install_memcache_docker.txt

PHP 5.6:
RUN apt-get update \
  && apt-get install -y libmemcached11 libmemcachedutil2 build-essential libmemcached-dev libz-dev \
  && pecl install memcached \
  && echo extension=memcached.so >> /usr/local/etc/php/conf.d/memcached.ini \
  && apt-get remove -y build-essential libmemcached-dev libz-dev \
  && apt-get autoremove -y \
  && apt-get clean \
  && rm -rf /tmp/pear

PHP 7:
git clone https://github.com/php-memcached-dev/php-memcached /usr/src/php/ext/memcached \
  && cd /usr/src/php/ext/memcached && git checkout -b php7 origin/php7 \
  && docker-php-ext-configure memcached \
  && docker-php-ext-install memcached 

I don't remember what we did with my colleague, but I would suggest to look into the configuration of your httpd server.