使用nsenter进入Docker容器

2014-09-10

Docker容器运行后,如何进入容器进行操作呢?起初我是用SSH。如果只启动一个容器,用SSH还能应付,只需要将容器的22端口映射到本机的一个端口即可。当我启动了五个容器后,每个容器默认是没有配置SSH Server的,安装配置SSHD,映射容器SSH端口,实在是麻烦。

我发现很多Docker镜像都是没有安装SSHD服务的,难道有其他方法进入Docker容器?

浏览了Docker的文档,我没有找到答案。还是要求助于无所不能的Google,万能的Google告诉我用nsenter吧。

在大多数Linux发行版中,util-linux包中含有nsenter.如果没有,你需要安装它.

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
cp nsenter /usr/local/bin

使用shell脚本 docker-enter,将如下代码保存为docker-enter,chomod +x docker-enter

    #!/bin/sh

    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

    if [ -z "$1" ]; then
        echo "Usage: `basename "$0"` CONTAINER [COMMAND [ARG]...]"
        echo ""
        echo "Enters the Docker CONTAINER and executes the specified COMMAND."
        echo "If COMMAND is not specified, runs an interactive shell in CONTAINER."
    else
        PID=$(docker inspect --format "{{.State.Pid}}" "$1")
        if [ -z "$PID" ]; then
            exit 1
        fi
        shift

        OPTS="--target $PID --mount --uts --ipc --net --pid --"

        if [ -z "$1" ]; then
            # No command given.
            # Use su to clear all host environment variables except for TERM,
            # initialize the environment variables HOME, SHELL, USER, LOGNAME, PATH,
            # and start a login shell.
            "$NSENTER" $OPTS su - root
        else
            # Use env to clear all host environment variables.
            "$NSENTER" $OPTS env --ignore-environment -- "$@"
        fi
    fi

运行 docker-enter <container id>,这样就进入到指定的容器中

关于nsenter更详细的使用方法见这里 https://github.com/jpetazzo/nsenter


标签: Docker