下面是我的dockerfile 文件

FROM php:7.1-fpm

RUN apt-get update -y \
    && apt-get install -y libfreetype6-dev libjpeg62-turbo-dev libpng-dev zlib1g-dev libcurl3 libwebp-dev zlib1g \
    && docker-php-ext-configure gd --with-freetype-dir=/usr/include/ --with-jpeg-dir=/usr/include/ --with-webp-dir=/usr/include/ --with-png-dir=/usr/include \
    && docker-php-ext-install -j$(nproc) gd \
    ##
    && apt-get install -y libicu-dev \
    && docker-php-ext-install -j$(nproc) intl \
    ##
    && apt-get install -y libbz2-dev \
    && docker-php-ext-install bz2 \
    ##
    && apt-get install -y libxml2-dev \
    && apt-get install -y libxslt-dev \
    && docker-php-ext-install soap \
    && docker-php-ext-install xsl \
    && docker-php-ext-install xmlrpc \
    && docker-php-ext-install wddx \
    ##
    && docker-php-ext-install zip \
    && docker-php-ext-install pcntl \
    && docker-php-ext-install opcache \
    && docker-php-ext-install pdo \
    && docker-php-ext-install pdo_mysql \
    && docker-php-ext-install mysqli \
    && docker-php-ext-install mbstring \
    && docker-php-ext-install sockets \
    ##
    && pecl install redis-3.1.3 \
    && docker-php-ext-enable --ini-name pecl.ini redis  \
    ##
    && cd /tmp \
    && curl -L -s -o cphalcon.tar.gz https://github.com/phalcon/cphalcon/archive/v3.4.0.tar.gz \
    && tar xzvf cphalcon.tar.gz \
    && cd /tmp/cphalcon-3.4.0/build \
    && ./install \
    && echo "extension=phalcon.so" > /usr/local/etc/php/conf.d/phalcon.ini \
    ##
    && cd /tmp \
    && curl -L -s -o swoole.tar.gz https://github.com/swoole/swoole-src/archive/v2.1.0.tar.gz \
    && tar xzvf swoole.tar.gz \
    && cd /tmp/swoole-src-2.1.0 \
    && phpize \
    && ./configure \
    && make && make install \
    && echo "extension=swoole.so" > /usr/local/etc/php/conf.d/swoole.ini \
    ##
    && cd /tmp \
    && rm -rf cphalcon* \
    && rm -rf swoole* \
    && rm -rf package* 

EXPOSE 9000
CMD ["php-fpm"]

这样子build是没有问题的，但是因为里面有apt-get update 所以非常慢，因此google了下，说是用国内的源即可 然后变更为如下：

FROM php:7.1-fpm

COPY ./sources.list .

RUN mv /etc/apt/sources.list /etc/apt/sources.list.bak && mv sources.list /etc/apt/ && apt-get update -y \
    && apt-get install -y libfreetype6-dev libjpeg62-turbo-dev libpng-dev zlib1g-dev libcurl3 libwebp-dev zlib1g \
    ......

sources.list 文件内容如下：

deb http://mirrors.163.com/debian/ jessie main non-free contrib
deb http://mirrors.163.com/debian/ jessie-updates main non-free contrib
deb http://mirrors.163.com/debian/ jessie-backports main non-free contrib
deb-src http://mirrors.163.com/debian/ jessie main non-free contrib
deb-src http://mirrors.163.com/debian/ jessie-updates main non-free contrib
deb-src http://mirrors.163.com/debian/ jessie-backports main non-free contrib
deb http://mirrors.163.com/debian-security/ jessie/updates main non-free contrib
deb-src http://mirrors.163.com/debian-security/ jessie/updates main non-free contrib

如果这样子build的话，就会报错：

The following information may help to resolve the situation:

The following packages have unmet dependencies:
 libfreetype6-dev : Depends: zlib1g-dev but it is not going to be installed or
                             libz-dev
 libpng12-dev : Depends: zlib1g-dev but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

我在想是这个163的源有问题么？但是不应该啊，

求助下大家，这个问题怎么解决？