使用nsenter进入docker container

先计算容器的PID：

PID=$(docker inspect --format {{.State.Pid}} <container_name_or_ID>)
solumuser@ubuntu14044:~/devstack$ docker ps
CONTAINER ID        IMAGE                                                                                                         COMMAND                CREATED             STATUS              PORTS               NAMES
e6551c6bf7e7        98b7ac1054f74e97840618198d699cec-java_app-20160517t175809236072150-1713a757d34ca340211473f322e0fc2406d3f65d   "/bin/bash -c 'sourc   16 hours ago        Up 16 hours                             nova-148a593f-d75c-4ac8-8cad-95c2ee7ffefd   
solumuser@ubuntu14044:~/devstack$ PID=$(docker inspect --format {{.State.Pid}} nova-148a593f-d75c-4ac8-8cad-95c2ee7ffefd )

进入容器：

nsenter --target $PID --mount --uts --ipc --net --pid
solumuser@ubuntu14044:~/devstack$ sudo nsenter --target $PID --mount --uts --ipc --net --pid
root@instance-0000000e:/# pwd
/
root@instance-0000000e:/# ls
app  bin  boot  dev  etc  home  lib  lib64  media  mnt  opt  proc  root  run  sbin  solum  srv  sys  tmp  usr  var





#!/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