Docker实践2：用Docker搭建hg-server
丘畅
如果有人已经将hg server的image做好了，那么我还要自己作吗？答案是拿来用吧。
一、安装
用hg为关键词搜索，得出以下结果：
$ docker search hg
NAME DESCRIPTION STARS OFFICIAL AUTOMATED
hgomez/gatling 1 [OK]
v7soft/hgdns 0 [OK]
hg8496/gridvis-service 0 [OK]
hgomez/di-centos6-myjenkins-lts 0 [OK]
jrandall/hgi-project 0 [OK]
hgomez/di-centos6-myartifactory 0 [OK]
hgomez/di-centos6-myjenkins 0 [OK]
hgomez/di-centos6-mynexus 0 [OK]
hgomez/di-centos6-myarchiva 0 [OK]
hg8496/piwigo 0 [OK]
hg8496/apache 0 [OK]
hgomez/di-centos6-mygitblit 0 [OK]
hgomez/di-centos6-mygitbucket 0 [OK]
jyotisingh/ubuntu-hg 0
hg8496/dokuwiki 0 [OK]
hg8496/owncloud 0 [OK]
misshie/ucsc-blat-hg19 0 [OK]
ussie/hg-exec adds mercurial to ubuntu:14.04. 0
misshie/ucsc-blat-hg38 0 [OK]
hg8496/gridvis-pc 0 [OK]
Test. Automated builds for this repo are b... 0 [OK]
hg8496/rsync 0 [OK]
secondbit/hgbundler 0
uotbw/hgamer3d Docker image for hgamer3d, see www.hgamer3... 0
hgomez/di-centos6-base 0 [OK]
hgweb貌似不错的选择，在github上的主页是https://github.com/amclain/docker-hgweb 。
将其pull下来，在漫长的等待中我也在思考着如何启动它。
主页上提供了它的Dockerfile，通过它我们就可以了解这个image是如果构造的。先来说说什么是Dockerfile。
二、Dockerfile
它是用户创建自定义镜像的文件。它通常分为四部分：基础镜像信息，维护者信息，镜像操作指令和容器启动时的指令。
#基础系统信息，基于ubuntu 14.04构建的
FROM ubuntu:14.04
MAINTAINER Alex McLain <alex@alexmclain.com>
RUN apt-get -qq update
#安装apache、hg、php5
RUN apt-get -y install apache2 apache2-utils curl mercurial php5 php5-cli php5-mcrypt
# TODO: Remove
#是的，vim确实很大，不安装为好
RUN apt-get -y install vim
RUN echo "colorscheme delek" > ~/.vimrc
# Configure hgweb
ADD hg/add.php /etc/default/hgweb/hg/
ADD hg/hgweb.config /etc/default/hgweb/hg/
ADD hg/hgweb.cgi /etc/default/hgweb/hg/
ADD hg/hgusers /etc/default/hgweb/hg/
# Configure Apache
ADD apache/hg.conf /etc/default/hgweb/apache/
RUN rm /etc/apache2/sites-enabled/*
RUN a2enmod rewrite && a2enmod cgi
ADD load-default-scripts /bin/
RUN chmod u+x /bin/load-default-scripts
#创建一个挂载点，本机或其他容器可以将其挂载。启动时用-v参数进行挂载
VOLUME /var/hg
VOLUME /etc/apache2/sites-available
#暴露的端口号，启动时要通过-p参数指定
EXPOSE 80
#启动时执行的命令
CMD load-default-scripts && service apache2 start && /bin/bash
三、启动
有了上述的背景，我们知道启动时要做两件事：指定端口号、挂载本地目录。
比如还是使用端口号80，那么只需用 -p 80:80即可。
比如本机目录hg-repos用来做hg repo的放置目录，只需 -v /home/linc/hg-repos:/var/hg/repos 挂载即可。
另外，我们还要将其启动在后台（Daemonized），加上-d参数。
完整启动命令如下：
docker run -idt -p 80:80 -v /home/linc/hg-repos:/var/hg/repos amclain/hgweb四、与后台容器交互
1.attach方法
docker 自带attach命令，但此命令的不方便之处在于，多个窗口（同时attach此容器）会同步显示操作，并且当一个窗口exit时，所有窗口都会退出，后台运行的容器也停止了。
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
b22cc1880b7a amclain/hgweb:latest "/bin/sh -c 'load-de 3 hours ago Up 3 hours 0.0.0.0:80->80/tcp high_almeida
$ docker attach b22cc1880b7a
root@b22cc1880b7a:/#
此工具需要从源码安装：
$ cd /tmp; curl https://www.kernel.org/pub/linux/utils/util-linux/v2.24/util-linux-2.24.tar.gz | tar -zxf-; cd util-linux-2.24;
$ ./configure --without-ncurses
$ make nsenter && sudo cp nsenter /usr/local/bin#docker
export DOCKER_HOST=tcp://localhost:4243
alias docker-pid="sudo docker inspect --format '{{.State.Pid}}'"
alias docker-ip="sudo docker inspect --format '{{ .NetworkSettings.IPAddress }}'"
#the implementation refs from https://github.com/jpetazzo/nsenter/blob/master/docker-enter
function docker-enter() {
if [ -e $(dirname "$0")/nsenter ]; then
# with boot2docker, nsenter is not in the PATH but it is in the same folder
NSENTER=$(dirname "$0")/nsenter
else
NSENTER=nsenter
fi
[ -z "$NSENTER" ] && echo "WARN Cannot find nsenter" && return
if [ -z "$1" ]; then
echo "Usage: `basename "$0"` CONTAINER [COMMAND [ARG]...]"
echo ""
echo "Enters the Docker CONTAINER and executes the specified COMMAND."
echo "If COMMAND is not specified, runs an interactive shell in CONTAINER."
else
PID=$(sudo docker inspect --format "{{.State.Pid}}" "$1")
if [ -z "$PID" ]; then
echo "WARN Cannot find the given container"
return
fi
shift
OPTS="--target $PID --mount --uts --ipc --net --pid"
if [ -z "$1" ]; then
# No command given.
# Use su to clear all host environment variables except for TERM,
# initialize the environment variables HOME, SHELL, USER, LOGNAME, PATH,
# and start a login shell.
#sudo $NSENTER "$OPTS" su - root
sudo $NSENTER --target $PID --mount --uts --ipc --net --pid su - root
else
# Use env to clear all host environment variables.
sudo $NSENTER --target $PID --mount --uts --ipc --net --pid env -i $@
fi
fi
}
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
beb178cd9335 amclain/hgweb:latest "/bin/sh -c 'load-de 11 seconds ago Up 10 seconds 0.0.0.0:80->80/tcp stoic_yonath
$ docker-enter beb178cd9335
root@beb178cd9335:~# ls
root@beb178cd9335:~# pwd
/root
五、快速启动hg-server
咱也写个alias放子bashrc中，如下：
alias docker-load-hg-server="sudo docker run -idt -p 80:80 -v /home/linc/hg-repos:/var/hg/repos amclain/hgweb"$ docker-load-hg-server
[sudo] password for linc:
beb178cd933502970fd12d9a4babecef5475a52d85a207066c665b4a620c5a62
改进
对于文件的挂载，其实直接挂镜像的/var/hg更好，这样里面的几个配置文件如hgusers hgweb.cgi hgweb.config，我们可以直接进行配置。
sudo docker run -idt -p 80:80 -v /home/linc/hg-repos:/var/hg amclain/hgweb
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