构建基于nginx-php-yaf的docker镜像

• 需求 : php7.1 + nginx
• php扩展： yaf、redis、ldap、pdo、mbstring、 mcrypt

阅读完本文后，你能解决以下常见问题：

• 如何写Dockerfile，并通过Dockerfile构建镜像。
• 如何通过supervisord管理进程，并将进程日志通过docker logs {container}输出

实现步骤

我们的镜像基于centos:7系统， Dockerfile代码如下：

FROM centos:7
MAINTAINER zhaowei@outlook.com
RUN rpm -Uvh http://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm \
    && rpm -Uvh https://sp.repo.webtatic.com/yum/el7/webtatic-release.rpm \
    && yum update -y \
    && yum install -y wget \
        sed \ 
        gcc \
        gcc-c++ \
        gd \
        gd-devel \
        gmp-devel \
        epel-release \
        net-tools \
        ntpdate \
        ntp \
        openssh-clients \ 
        curl \
        crontabs \
        openssl \
        openssl-devel \
        nginx \
        squid \
        php71w \
        php71w-fpm \
        php71w-gd \
        php71w-soap \
        php71w-pdo_mysql \
        php71w-pear \
        php71w-devel \  
        php71w-mbstring \
        php71w-mcrypt \
        php71w-ldap \
    && yum update -y ntp ntpdate kernel-headers \
    && yum clean all \
    && sed -i 's/http_access deny all/#http_access deny all/g' /etc/squid/squid.conf \
    && cd /tmp \
    && wget -O get-pip.py https://bootstrap.pypa.io/get-pip.py \
    && python get-pip.py \
    && pip install supervisor \
    && mkdir -p /etc/supervisor.d/*.conf \
    && pecl install mongodb \
    && pecl install yaf \
    && wget -c https://github.com/phpredis/phpredis/archive/3.1.4.tar.gz \
        && tar zxvf 3.1.4.tar.gz \
        && cd phpredis-3.1.4 \
        && phpize \
        && ./configure \
        && make \
        && make install \
        && cd .. \
        && rm -rf phpredis* \
    && rm 3.1.4.tar.gz \ 
    && echo "" >> /etc/php.ini \
    && echo "extension=redis.so" >> /etc/php.ini \
    && echo "extension=yaf.so" >> /etc/php.ini \
    && echo "extension=mongodb.so" >> /etc/php.ini \
    && echo "[yaf]" >> /etc/php.ini \
    && echo "yaf.use_namespace = 1" >> /etc/php.ini 
COPY ./supervisord.conf /etc/
COPY ./default.conf /etc/nginx/conf.d/
COPY ./nginx.conf /etc/supervisor.d/
COPY ./php.conf /etc/supervisor.d/
COPY ./ntpdate.conf /etc/supervisor.d/
COPY ./nginx.conf.def /etc/nginx/nginx.conf
COPY ./index.php /data/work/code/
EXPOSE 80 443 3128
WORKDIR /data/work/code
CMD ["supervisord","-c","/etc/supervisord.conf"]

问题

子进程stdout如何重定向到supervisord

Supervisor的监督进程supervisord可以捕获所管理子进程的stdout及stderr，并可以配置为写入日志文件
镜像初步构建成功时，运行容器，并通过 docker logs -f {container} 查看容器日志，总是提示错误， 如下：

2017-11-09 07:41:41,256 CRIT uncaptured python exception, closing channel <POutputDispatcher at 36463248 for <Subprocess at 35644984 with name nginx in state RUNNING> (stderr)> (<type 'exceptions.IOError'>:[Errno 29] Illegal seek [/usr/lib/python2.7/site-packages/supervisor/supervisord.py|runforever|227] [/usr/lib/python2.7/site-packages/supervisor/dispatchers.py|handle_read_event|232] [/usr/lib/python2.7/site-packages/supervisor/dispatchers.py|record_output|166] [/usr/lib/python2.7/site-packages/supervisor/dispatchers.py|_log|142] [/usr/lib/python2.7/site-packages/supervisor/loggers.py|info|275] [/usr/lib/python2.7/site-packages/supervisor/loggers.py|log|293] [/usr/lib/python2.7/site-packages/supervisor/loggers.py|emit|186] [/usr/lib/python2.7/site-packages/supervisor/loggers.py|doRollover|211])

经过了N多次查询，N多次尝试，终于找到原因，原来是在配置supervisord管理的子进程文件时，如果配置了stdout_logfile=/dev/stdout, 则必须一块配置stdout_logfile_maxbytes=0

查找的资料说明如下：

If anyone stumbles upon this error like me, be aware that the mentioned options apply to the [supervisord] section, within [program:x] sections, you need to use stdout_logfile_maxbytes = 0and/or stderr_logfile_maxbytes = 0 respectively.

using stdout_logfile=/dev/stdout along with stdout_logfile_maxbytes=0

对于需要将supervisord管理的子进程的日志输出到stdout的program， 配置如下：

[program:php7-fpm]
command=/usr/local/sbin/php-fpm
autostart = true
stderr_logfile = /dev/stdout
stdout_logfile = /dev/stdout
stdout_logfile_maxbytes = 0
stderr_logfile_maxbytes = 0

参见： http://veithen.github.io/2015/01/08/supervisord-redirecting-stdout.html

php-fpm 的错误日志如何定向到docker logs

看到 https://github.com/docker-library/php/issues/63 解释，将error_log及access.log的配置改成如下error_log=/proc/self/fd/2 和 access.log=/proc/self/fd2即可，一直不明白，/proc/self/fd/2和/dev/stdout /dev/stderr有什么联系，经过ls -al /dev 才明白：

lrwxrwxrwx  1 root root   15 Nov  9 07:44 stderr -> /proc/self/fd/2
lrwxrwxrwx  1 root root   15 Nov  9 07:44 stdin -> /proc/self/fd/0
lrwxrwxrwx  1 root root   15 Nov  9 07:44 stdout -> /proc/self/fd/1

对于我们的需求，是将错误及access信息都在docker logs 中显示，所以，我们配置php-fpm.conf如下：

[global]
error_log=/proc/self/fd/1

文件/etc/php-fpm.d/www.conf配置如下：

php_admin_value[error_log] = /proc/self/fd/1
slowlog = /proc/self/fd/1
catch_workers_output = yes
clear_env=no