镜像：https://hub.docker.com/r/richarvey/nginx-php-fpm/
php版本：FROM php:7.1.11-fpm-alpine
下载镜像并启动容器：
docker run -d richarvey/nginx-php-fpm
进入容器：
docker exec -it 08f7c84d5b84 bash
1 php -m|grep redis
2 mkdir -p /usr/src/php/ext/redis
3 curl -L https://github.com/phpredis/phpredis/archive/3.0.0.tar.gz | tar xvz -C /usr/src/php/ext/redis –strip 1
4 echo ‘redis’ >> /usr/src/php-available-exts
5 docker-php-ext-install redis
6 php -m|grep redis
手工验证没问题，将命令写入dockerfile：
RUN mkdir -p /usr/src/php/ext/redis \
&& curl -L https://github.com/phpredis/phpredis/archive/$PHPREDIS_VERSION.tar.gz | tar xvz -C /usr/src/php/ext/redis –strip 1 \
&& echo ‘redis’ >> /usr/src/php-available-exts \
&& docker-php-ext-install redis
参考：
https://stackoverflow.com/questions/31369867/how-to-install-php-redis-extension-using-the-official-php-docker-image-approach
memcached 扩展：
参考：https://stackoverflow.com/questions/40894385/how-can-i-install-the-php-memcached-extension-on-dockers-php7-alpine-image
安装memcached扩展：
ENV MEMCACHED_DEPS zlib-dev libmemcached-dev cyrus-sasl-dev
RUN apk add –no-cache –update libmemcached-libs zlib
RUN set -xe \
&& apk add –no-cache –update –virtual .phpize-deps $PHPIZE_DEPS \
&& apk add –no-cache –update –virtual .memcached-deps $MEMCACHED_DEPS \
&& pecl install memcached \
&& echo “extension=memcached.so” > /usr/local/etc/php/conf.d/docker-php-ext-memcached.ini \
&& rm -rf /usr/share/php7 \
&& rm -rf /tmp/* \
&& apk del .memcached-deps .phpize-deps