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Docker容器管理

程序员文章站 2024-03-11 19:08:13
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目录

  1. 创建容器
  2. 启动容器
  3. 停止容器
  4. 进入容器
  5. 删除容器
  6. 容器迁移

1. 创建容器

docker创建容器可以用docker create命令来执行。

[[email protected] ~]# docker create -it debian:latest
Unable to find image 'debian:latest' locally
latest: Pulling from library/debian
a719479f5894: Pull complete 
91bac885982d: Pull complete 
Digest: sha256:a1577aa9dde28e51fb56dbad63b86b7db3ea44d4474ef656671c5a6596073d8c
Status: Downloaded newer image for debian:latest
f4086492e895f3203f56ec545990bc0b5da69be3c3e3c70e2ce1188d685c9c16
[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
f4086492e895        debian:latest       "/bin/bash"         5 seconds ago       Created                                 elegant_curie
[[email protected] ~]#

通过docker create命令创建的容器是停止的,我们可以用docker ps -a -q命令来查看哪些是停止状态的容器。

[[email protected] ~]# docker ps -a -q
f4086492e895
[[email protected] ~]#

2. 启动容器

2.1 创建容器

上面说过了通过docker create创建的容器是停止状态的,那么我们就可以用docker start命令来启动容器。

[[email protected] ~]# docker start f4086492e895
f4086492e895
[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
f4086492e895        debian:latest       "/bin/bash"         8 minutes ago       Up 6 seconds                            elegant_curie
[[email protected] ~]#

2.2 创建启动容器

其实这样有点繁琐,先创建容器再进行启动,其实我们可以用docker run命令来实现直接创建启动一个容器的,其实docker run命令等价于先执行docker create然后执行docker start命令。

[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

[[email protected] ~]# docker run debian:latest /bin/echo -e "\n\nHello, Here is Legion Blog."
Unable to find image 'debian:latest' locally
latest: Pulling from library/debian
a719479f5894: Pull complete 
91bac885982d: Pull complete 
Digest: sha256:a1577aa9dde28e51fb56dbad63b86b7db3ea44d4474ef656671c5a6596073d8c
Status: Downloaded newer image for debian:latest
Hello, Here is Legion Blog.

[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND                    CREATED             STATUS                     PORTS               NAMES
68e25a09499d        debian:latest       "/bin/echo -e '\\n\\nHe"   7 seconds ago       Exited (0) 7 seconds ago                       loving_nobel

[[email protected] ~]# docker images |grep debian
debian              latest              91bac885982d        5 days ago          125.1 MB

[[email protected] ~]# docker ps -a -q
68e25a09499d

[[email protected] ~]#

当使用docker run命令创建启动容器时,Docker在后台运行的标准操作有下面几个步骤:

  1. 检测本地是否存在指定的镜像,不存在就从公有仓库下载
  2. 利用镜像创建并启动一个容器
  3. 分配一个文件系统,并在只读的镜像层外面挂载一层可读写层
  4. 从宿主主机配置的网桥接口中桥接一个虚拟接口到容器中去
  5. 从地址池配置一个IP地址给容器
  6. 执行用户指定的应用程序
  7. 执行完毕后终止容器

2.3 容器的守护状态运行。

在实际应用中我们更多的是需要容器在后台以守护状态(Daemonized)形式运行,我们可以使用-d参数来实现容器的后台守护状态运行。

[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND                    CREATED             STATUS                      PORTS               NAMES
a578b01bc9bd        debian:latest       "/bin/bash"                15 minutes ago      Exited (0) 8 minutes ago                        sick_lalande
68e25a09499d        debian:latest       "/bin/echo -e '\\n\\nHe"   34 minutes ago      Exited (0) 34 minutes ago                       loving_nobel

[[email protected] ~]# docker run -d debian /bin/bash -c "while true; do echo hello docker; sleep 3;done"
a2bda91ae015d5166a31af082fb78126d054633cc381cc75dbd5e7894d5dac6e

[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND                    CREATED             STATUS                      PORTS               NAMES
a2bda91ae015        debian              "/bin/bash -c 'while "     4 seconds ago       Up 3 seconds                                    loving_chandrasekhar
a578b01bc9bd        debian:latest       "/bin/bash"                17 minutes ago      Exited (0) 9 minutes ago                        sick_lalande
68e25a09499d        debian:latest       "/bin/echo -e '\\n\\nHe"   35 minutes ago      Exited (0) 35 minutes ago                       loving_nobel

[[email protected] ~]# docker logs a2bda91ae015
hello docker
hello docker
hello docker
hello docker
hello docker
hello docker
hello docker
hello docker
hello docker

上面我们就是用Debian镜像运行了一个容器,容器在后台以守护进程的方式运行着while true; do echo hello docker; sleep 3;done循环,最后我们通过docker logs a2bda91ae015命令可以看到容器的输出信息,证实这个容器一直在后台运行着。

3. 停止容器

我们可以使用docker stop命令来停止一个运行中的容器

命令用法:docker stop [-t|--time[=10]]

它会首先向容器发送SIGTERM信号,等待一段时间后(默认为10秒),再发送SIGKILL信号来终止容器。

当docker容器中指定的应用终结时,容器也自动终止。例如上面我用用exit命令退出那个终端的时候所创建的容器也立刻终止了。

我们可以用docker stop命令终止一个容器也可以使用docker start命令来重新启动,也可以使用docker restart命令来将一个运行终端额容器终止后再重新启动它。

[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND                    CREATED             STATUS                      PORTS               NAMES
a2bda91ae015        debian              "/bin/bash -c 'while "     11 minutes ago      Up 11 minutes                                   loving_chandrasekhar
a578b01bc9bd        debian:latest       "/bin/bash"                29 minutes ago      Exited (0) 21 minutes ago                       sick_lalande
68e25a09499d        debian:latest       "/bin/echo -e '\\n\\nHe"   47 minutes ago      Exited (0) 47 minutes ago                       loving_nobel
[[email protected] ~]# docker stop a2bda91ae015
a2bda91ae015
[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND                    CREATED             STATUS                       PORTS               NAMES
a2bda91ae015        debian              "/bin/bash -c 'while "     12 minutes ago      Exited (137) 4 seconds ago                       loving_chandrasekhar
a578b01bc9bd        debian:latest       "/bin/bash"                29 minutes ago      Exited (0) 22 minutes ago                        sick_lalande
68e25a09499d        debian:latest       "/bin/echo -e '\\n\\nHe"   48 minutes ago      Exited (0) 48 minutes ago                        loving_nobel
[[email protected] ~]# docker start a2bda91ae015
a2bda91ae015
[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND                    CREATED             STATUS                      PORTS               NAMES
a2bda91ae015        debian              "/bin/bash -c 'while "     12 minutes ago      Up 2 seconds                                    loving_chandrasekhar
a578b01bc9bd        debian:latest       "/bin/bash"                29 minutes ago      Exited (0) 22 minutes ago                       sick_lalande
68e25a09499d        debian:latest       "/bin/echo -e '\\n\\nHe"   48 minutes ago      Exited (0) 48 minutes ago                       loving_nobel
[[email protected] ~]# docker restart a2bda91ae015
a2bda91ae015
[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND                    CREATED             STATUS                      PORTS               NAMES
a2bda91ae015        debian              "/bin/bash -c 'while "     12 minutes ago      Up 3 seconds                                    loving_chandrasekhar
a578b01bc9bd        debian:latest       "/bin/bash"                30 minutes ago      Exited (0) 22 minutes ago                       sick_lalande
68e25a09499d        debian:latest       "/bin/echo -e '\\n\\nHe"   48 minutes ago      Exited (0) 48 minutes ago                       loving_nobel
[[email protected] ~]# docker stop --time=2 a2bda91ae015
a2bda91ae015
[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND                    CREATED             STATUS                       PORTS               NAMES
a2bda91ae015        debian              "/bin/bash -c 'while "     13 minutes ago      Exited (137) 3 seconds ago                       loving_chandrasekhar
a578b01bc9bd        debian:latest       "/bin/bash"                30 minutes ago      Exited (0) 23 minutes ago                        sick_lalande
68e25a09499d        debian:latest       "/bin/echo -e '\\n\\nHe"   48 minutes ago      Exited (0) 48 minutes ago                        loving_nobel
[[email protected] ~]#

4. 进入容器

在使用docker run -d参数时候,容器启动后会进入后台,用户无法看到容器中的信息。某些时候我们是需要进入容器进行操作的,这里我们就可以使用 docker attach、docker exec命令或者nsenter工具等来完成。

4.1 attach命令

docker attach是一个Docker自带的命令,下面来说说attach命令的使用方法:

[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
[[email protected] ~]# docker run -t -i -d debian
7f16264f7ab46e68b70dc8d982300c3a277d273cb425be6be739915c563ccb3c
[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
7f16264f7ab4        debian              "/bin/bash"         3 seconds ago       Up 2 seconds                            tender_raman
[[email protected] ~]# docker attach 7f1
[email protected]:/# 
[email protected]:/# ps
  PID TTY          TIME CMD
    1 ?        00:00:00 bash
    6 ?        00:00:00 ps
[email protected]:/# exit
exit
[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED              STATUS                     PORTS               NAMES
7f16264f7ab4        debian              "/bin/bash"         About a minute ago   Exited (0) 2 seconds ago                       tender_raman
[[email protected] ~]#

其实使用docker attach命令有时候很不方便,当多个窗口同时attach到同一个容器的时候,所有窗口都会同步显示,当某个窗口因命令阻塞的时候,其他窗口也无法执行操作了。

4.2 exec命令

在Docker1.3版本开始,提供了一个更方便的命令exec。可以直接在容器内运行命令。

[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                     PORTS               NAMES
7f16264f7ab4        debian              "/bin/bash"         5 minutes ago       Exited (0) 4 minutes ago                       tender_raman
[[email protected] ~]# docker start 7f16264f7ab4
7f16264f7ab4
[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
7f16264f7ab4        debian              "/bin/bash"         5 minutes ago       Up 2 seconds                            tender_raman
[[email protected] ~]# docker exec -ti 7f16264f7ab4 /bin/bash
[email protected]:/# ps 
  PID TTY          TIME CMD
    6 ?        00:00:00 bash
   10 ?        00:00:00 ps
[email protected]ab4:/# date
Sun Nov 15 07:59:29 UTC 2015
[email protected]:/#

4.3 nsenter工具

1. nsenter的安装

nsenter工具在util-linux包的2.23版本后都包含。如果系统中的util-linux包中没有这个命令,那么可以通过源码编译安装。

检查是否安装nsenter工具:

[[email protected] ~]# which nsenter
/usr/bin/nsenter
[[email protected] ~]# nsenter -V
nsenter,?? util-linux 2.23.2
[[email protected] ~]#

下载并编译安装:

[[email protected] ~]# wget https://www.kernel.org/pub/linux/utils/util-linux/v2.27/util-linux-2.27.tar.xz
[[email protected] ~]# tar xf util-linux-2.27.tar.xz 
[[email protected] ~]# cd util-linux-2.27/
[[email protected] ~/util-linux-2.27]# ./configure --without-ncurses
[[email protected] ~/util-linux-2.27]# make nsenter
[[email protected] ~/util-linux-2.27]# \cp nsenter /usr/bin/
[[email protected] ~/util-linux-2.27]# which nsenter 
/usr/bin/nsenter
[[email protected] ~/util-linux-2.27]# nsenter -V
nsenter,来自 util-linux 2.27
[[email protected] ~/util-linux-2.27]#

2. nsenter的使用

为了使用nsenter工具连接到容器,我们首先需要找到容器的进程PID号,可以通过下面的命令获取。

获取PID:

f-docker-pid() { docker inspect --format "{{ .State.Pid}}" $1; }
docker-pid <CONTAINER ID>
nsenter --target <PID> --mount --uts --ipc --net --pid

操作步骤:

[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
7f16264f7ab4        debian              "/bin/bash"         34 minutes ago      Up 29 minutes                           tender_raman
[[email protected] ~]# f-docker-pid() { docker inspect --format "{{ .State.Pid}}" $1; }
[[email protected] ~]# nsenter --target $(f-docker-pid 7f16264f7ab4) --mount --uts --ipc --net --pid
[email protected]:/# date
Sun Nov 15 08:29:37 UTC 2015
[email protected]:/# logout
[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
7f16264f7ab4        debian              "/bin/bash"         36 minutes ago      Up 31 minutes                           tender_raman
[[email protected] ~]#

为了以后方便使用我这做了shell函数写到.bashrc文件了。

[[email protected] ~]# echo 'tools-nsenter() { nsenter --target $(docker inspect --format "{{ .State.Pid}}" $1) --mount --uts --ipc --net --pid; }' >> ~/.bashrc
[[email protected] ~]# source ~/.bashrc
[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
7f16264f7ab4        debian              "/bin/bash"         58 minutes ago      Up 53 minutes                           tender_raman
[[email protected] ~]# tools-nsenter 7f16264f7ab4
[email protected]:/# date
Sun Nov 15 08:53:22 UTC 2015
[email protected]:/# ps
  PID TTY          TIME CMD
  216 ?        00:00:00 bash
  253 ?        00:00:00 ps
[email protected]:/# logout
[[email protected] ~]#

这样以后就可以更方便的使用nsenter命令来连接容器。

5. 删除容器

删除容器我们可以使用docker rm命令,被删除的容器需要是终止状态的。

命令用法:docker rm [OPTIONS] CONTAINER [CONTINER...]

options:

  • -f, --force=false:强项终止并删除一个运行中的容器。
  • -l, --link=false:删除容器的连接,但保留容器。
  • -v, --volumes=false:删除容器挂载的数据卷。
[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
b8971dc66962        debian              "/bin/bash"         9 seconds ago       Up 8 seconds                            agitated_chandrasekhar
[[email protected] ~]# docker rm b8971dc66962
Error response from daemon: Conflict, You cannot remove a running container. Stop the container before attempting removal or use -f
Error: failed to remove containers: [b8971dc66962]
[[email protected] ~]# docker rm -f b8971dc66962
b8971dc66962
[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
[[email protected] ~]#

六. 容器迁移

6.1 导出容器

导出容器是指一个已经创建的容器导出到一个文件,不管此时这个容器是否处于运行状态,可以使用docker export命令。

命令用法:docker export CONTAINER

[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
[[email protected] ~]# docker run -t -i -d debian
0291b910e062dd348696386875f3e73e55a32366540bad1742f45bfcc987a455
[[email protected] ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
0291b910e062        debian              "/bin/bash"         2 seconds ago       Up 1 seconds                            gloomy_galileo
[[email protected] ~]# docker export 0291b910e062 > debian-2015_11_15.tar
[[email protected] ~]# ls -l debian-2015_11_15.tar
0644 -rw-r--r-- 1 root root 130947584 11月 15 09:16 debian-2015_11_15.tar
[[email protected] ~]#

6.2 导入容器

导入容器是指将一个指定的文件导入到容器,可以使用命令docker import。

命令用法:docker import CONTAINER

[[email protected] ~]# docker export 0291b910e062 > debian-2015_11_15.tar
[[email protected] ~]# ls -l debian-2015_11_15.tar
0644 -rw-r--r-- 1 root root 130947584 11月 15 09:16 debian-2015_11_15.tar
[[email protected] ~]# cat debian-2015_11_15.tar | docker import - runbash/debian:v1.0
0b1d5532571e3f829a2c90e7353262c1f6f18bf0cbdd1930fa324344bf5cebc8
[[email protected] ~]# docker images 
REPOSITORY          TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
runbash/debian      v1.0                0b1d5532571e        13 seconds ago      125.1 MB
ubuntu              latest              d1b426312675        14 hours ago        286.2 MB
lookback/ubuntu     baseos              d1b426312675        14 hours ago        286.2 MB
ubuntu              14.04               e9ae3c220b23        5 days ago          187.9 MB
debian              latest              91bac885982d        5 days ago          125.1 MB
centos              6.7                 7e8fbd86f46d        4 weeks ago         190.6 MB
[[email protected] ~]#