How to install php-redis extension using the official PHP Docker image approach?

Question

I want to build my PHP-FPM image with php-redis extension based on the official PHP Docker image, for example, using this Dockerfile: php:5.6-fpm.

The docs

Answer 1

Slightly revised version of starikovs and skyred answers for current version of the docker image. Tested on php:5-fpm-alpine

# install phpredis extension
ENV PHPREDIS_VERSION 2.2.8

ADD https://github.com/phpredis/phpredis/archive/$PHPREDIS_VERSION.tar.gz /tmp/redis.tar.gz
RUN tar xzf /tmp/redis.tar.gz -C /tmp \
    && mkdir -p /usr/src/php/ext \
    && mv /tmp/phpredis-$PHPREDIS_VERSION /usr/src/php/ext/redis \
    && echo 'redis' >> /usr/src/php-available-exts \
    && docker-php-ext-install redis \
    && rm -rf /usr/src/php/ext/redis