使用docker-enter来进入docker容器

docker容器没起sshd服务的时候,还想进入docker怎么办,我们可以使用nsenter进入docker容器的命名空间namespace来虚拟登入docker容器。
nsenter一般默认自带了,没有的话,安装下。然后把如下这个脚本命名成docker-enter或者别的名字,赋执行权限,放入$PATH下即可,使用方式:docker-enter <container-id>

#!/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