一、使用Docker Compose 部署应用简介¶
Docker Compose能够在Docker节点上，以单引擎模式(Single-Engine Mode)进行多容器应用的部署和管理。
Docker Compose通过一个声明式的配置文件描述整个应用，使用一条命令完成部署。而当应用部署成功后，还可以通过一系列简单的命令实现对其完整生命周期的管理。甚至，配置文件还可以置于版本控制系统中进行存储和管理。
二、使用Docker Compose 部署应用详解¶
2.1 Docker Compose背景¶
2014年Docker公司收购了Orchard公司，并将Fig更名为Docker Compose。命令行工具由fig更名为docker-compose,并自此成为绑定在Docker引擎之上的外部工具。
到今天为至，Docker Compose仍然是一个需要在Docker主机上进行安装的外部python工具。使用它时，首先编写定义多容器(多服务)应用的YAML文件，然后将其交由docker-compose命令处理，Docker Compose就会基于Docker引擎API完成应用的部署。
2.2 安装Docker Compose¶
参考基于Ubuntu版本和Centos版本安装和卸载Docker Compose进行安装。
2.3 Compose文件¶
Docker Compose使用YAML文件来定义多服务的应用。YAML是JSON的一个子集。
Docker Compose默认使用文件名docker-compose.yml。也可以使用-f参数指定具体文件。
2.3.1 Compose文件内容¶
以下Compose文件定义了一个包含两个服务(web-fe和redis)的小型Flask应用。该文件能够对访问者进行计数并将其保存到Redis的简单的Web服务。
Compose文件内容如下:
version: "3.5"
services:
web-fe:
build: .
command: python app.py
ports:
- target: 5000
published: 5000
networks:
- counter-net
volumes:
- type: volume
source: counter-vol
target: /code
redis:
image: "redis:alpine"
networks:
counter-net:
networks:
counter-net:
文件内容包含4个一级key:version、services、networks、volumes。 version总是位于文件的第一行，用来定义Compose文件格式(主要是API)的版本； services用于定义不同的应用服务。案例中定义了两个服务，一个名为web-fe的web前端服务以及一个redis的内存数据库服务。 networks用于指引Docker创建新的网络。默认情况下，Docker Compose创建Bridge网络。 volumes用于指引Docker来创建新的卷。
2.3.2 Compose文件深入分析¶
services定义了两个二级key:web-fe和redis。
web-fe服务定义中，包含以下指令: 1、build 【.】指定Docker基于当前目录(.)下Dockerfile中定义的指令来构建一个新镜像。该镜像会被用于启动该服务的容器。 2、command python app.py指定Docker在容器中执行名为app.py的Python脚本作为主程序。 3、ports 指定Docker将容器内(-target)的5000端口映射到主机(published)的5000端口。表示发送到Docker主机5000端口的流量会被转发到容器的5000端口。容器中的应用监听端口5000。 4、networks 让Docker可以将服务连接到指定的网络上。对于Overlay网络来说，它还需要定义一个attachable标志，这样独立容器才可以连接上。 5、volumes 指定Docker将counter-vol卷(source:)挂载到容器内的/code(target:)。
小结: Docker Compose会调用Docker来为web-fe服务部署一个独立的容器。该容器基于与Compose文件位于同一目录的Dockerfile构建的镜像。基于该镜像启动的容器会运行app.py作为主程序，将5000端口暴露给宿主机，连接到counter-net网络上，并挂载一个卷到/code。
redis服务定义中，包含以下指令: 1、image redis:alpine使得Docker基于redis:alpine镜像启动一个独立的名为redis的容器。这个镜像会被从Docker Hub上拉取下来。 2、networks 配置redis容器连接到counter-net网络。
说明:由于web-fe服务和redis服务都连接到counter-net网络，因此它们可以通过名称解析到对方的地址！！！
三、使用Docker Compose部署应用¶
3.1 克隆应用代码¶
1、执行git https://github.com/nigelpoulton/counter-app.git命令从GitHub克隆代码。
root@zq-virtual-machine:/home/zq/Desktop# git clone https://github.com/nigelpoulton/counter-app.git
3.2 查看应用代码¶
1、执行cd和ls命令查看克隆后的文件内容。
root@zq-virtual-machine:/home/zq/Desktop# cd counter-app/
root@zq-virtual-machine:/home/zq/Desktop/counter-app# ls
app.py Dockerfile requirements.txt
docker-compose.yml README.md
3.3 开始部署应用¶
1、counter-app/目录视图下执行docker-compose up &命令启动Docker Compose。其中&参数代表日志回显给终端窗口。(-d参数是在后台运行)
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker-compose up &
[1] 2717
[+] Running 7/7-machine:/home/zq/Desktop/counter-app#
⠿ redis Pulled 12.1s
⠿ 213ec9aee27d Pull complete 3.2s
⠿ c99be1b28c7f Pull complete 3.4s
⠿ 8ff0bb7e55e3 Pull complete 3.8s
⠿ dedc3f029c28 Pull complete 5.6s
⠿ 820ef2f65f1b Pull complete 5.8s
⠿ 2117f9ecd795 Pull complete 6.0s
[+] Building 48.8s (10/10) FINISHED
=> [internal] load build definition from Dockerfile 0.2s
=> => transferring dockerfile: 147B 0.0s
=> [internal] load .dockerignore 0.2s
=> => transferring context: 2B 0.0s
=> [internal] load metadata for docker.io/library/python:3.6-alpine 5.3s
=> [auth] library/python:pull token for registry-1.docker.io 0.0s
=> [internal] load build context 0.1s
=> => transferring context: 30.36kB 0.0s
=> [1/4] FROM docker.io/library/python:3.6-alpine@sha256:579978dec46026 4.8s
=> => resolve docker.io/library/python:3.6-alpine@sha256:579978dec46026 0.0s
=> => sha256:579978dec4602646fe1262f02b96371779bfb0294e 1.65kB / 1.65kB 0.0s
=> => sha256:bc3447f6ba006c2268ccab840236cd1e27502a1d91 1.37kB / 1.37kB 0.0s
=> => sha256:3a9e80fa460687aa888ebe54540132662b58a3bb1a 8.08kB / 8.08kB 0.0s
=> => sha256:59bf1c3509f33515622619af21ed55bbe26d24913c 2.82MB / 2.82MB 1.6s
=> => sha256:8786870f287676cca49c1e1e5029467c087ad2 282.15kB / 282.15kB 1.8s
=> => sha256:acb0e804800ed3c10624ddeac73a6ebd3f2d6dbb 10.18MB / 10.18MB 3.2s
=> => extracting sha256:59bf1c3509f33515622619af21ed55bbe26d24913cedbca 0.2s
=> => sha256:52bedcb3e853dd5d782c46d387f2af404af9ec75c2aba3 229B / 229B 2.4s
=> => sha256:b064415ed3d75cd9bf462c4ea1a29aebe67dfe8fc7 2.21MB / 2.21MB 3.3s
=> => extracting sha256:8786870f287676cca49c1e1e5029467c087ad293b824fcd 0.2s
=> => extracting sha256:acb0e804800ed3c10624ddeac73a6ebd3f2d6dbb03970f0 0.5s
=> => extracting sha256:52bedcb3e853dd5d782c46d387f2af404af9ec75c2aba3a 0.1s
=> => extracting sha256:b064415ed3d75cd9bf462c4ea1a29aebe67dfe8fc76e672 0.4s
=> [2/4] ADD . /code 0.3s
=> [3/4] WORKDIR /code 0.1s
=> [4/4] RUN pip install -r requirements.txt 36.6s
=> exporting to image 1.1s
=> => exporting layers 1.1s
=> => writing image sha256:48da14617ca06fad52d56e7ef058c591412f0c51b93f 0.0s
=> => naming to docker.io/library/counter-app_web-fe 0.0s
Use 'docker scan' to run Snyk tests against images to find vulnerabilities and learn how to fix them
[+] Running 4/4
⠿ Network counter-app_counter-net Created 0.1s
⠿ Volume "counter-app_counter-vol" Created 0.0s
⠿ Container counter-app-redis-1 C... 0.5s
⠿ Container counter-app-web-fe-1 Created 0.6s
Attaching to counter-app-redis-1, counter-app-web-fe-1
counter-app-redis-1 | 1:C 06 Oct 2022 01:49:06.445 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
counter-app-redis-1 | 1:C 06 Oct 2022 01:49:06.445 # Redis version=7.0.5, bits=64, commit=00000000, modified=0, pid=1, just started
counter-app-redis-1 | 1:C 06 Oct 2022 01:49:06.445 # Warning: no config file specified, using the default config. In order to specify a config file use redis-server /path/to/redis.conf
counter-app-redis-1 | 1:M 06 Oct 2022 01:49:06.446 * monotonic clock: POSIX clock_gettime
counter-app-redis-1 | 1:M 06 Oct 2022 01:49:06.447 * Running mode=standalone, port=6379.
counter-app-redis-1 | 1:M 06 Oct 2022 01:49:06.447 # Server initialized
counter-app-redis-1 | 1:M 06 Oct 2022 01:49:06.447 # WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
counter-app-redis-1 | 1:M 06 Oct 2022 01:49:06.447 * Ready to accept connections
counter-app-web-fe-1 | * Serving Flask app 'app' (lazy loading)
counter-app-web-fe-1 | * Environment: production
counter-app-web-fe-1 | WARNING: This is a development server. Do not use it in a production deployment.
counter-app-web-fe-1 | Use a production WSGI server instead.
counter-app-web-fe-1 | * Debug mode: on
counter-app-web-fe-1 | * Running on all addresses.
counter-app-web-fe-1 | WARNING: This is a development server. Do not use it in a production deployment.
counter-app-web-fe-1 | * Running on http://172.18.0.2:5000/ (Press CTRL+C to quit)
counter-app-web-fe-1 | * Restarting with stat
counter-app-web-fe-1 | * Debugger is active!
counter-app-web-fe-1 | * Debugger PIN: 355-203-816
说明:默认docker-compose up会查找名为docker-compose.yml或docker-compose.yaml的Compose文件。如果Compose文件是其他文件名，需要-f参数指定文件名。
2、执行docker image ls命令查看Docker Compose创建的镜像、容器、网络和卷。这里需要注意，Docker Compose会将项目名称(counter-app)和Compose文件中定义的资源名称web-fe连起来，作为新构建镜像的名称。
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker image ls
REPOSITORY TAG IMAGE ID CREATED SIZE
counter-app_web-fe latest 48da14617ca0 9 minutes ago 55.5MB
redis alpine 0139e7020436 13 days ago 28.5MB
3、执行docker container ls命令查看启动容器。观察到，每个容器的名称都以项目名称为前缀。同时，它们还以一个数字为后缀用于标识容器实例序号，这是因为Docker Compose允许扩缩容。其中counter-app_web-fe运行的是应用的WEB前端。
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker container ls
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
9e477d785e98 redis:alpine "docker-entrypoint.s…" 16 minutes ago Up 16 minutes 6379/tcp counter-app-redis-1
05757fc563f9 counter-app_web-fe "python app.py" 16 minutes ago Up 16 minutes 0.0.0.0:5000->5000/tcp, :::5000->5000/tcp counter-app-web-fe-1
4、执行docker network ls命令查看网络。这里观察到生成名为counter-app_counter-net的网络。
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker network ls
NETWORK ID NAME DRIVER SCOPE
7db9b084e73d bridge bridge local
15c8b59f9c64 counter-app_counter-net bridge local
0692b1905fd1 host host local
a096b69b36e5 none null local
5、执行docker volume ls命令查看卷，这里观察到生成名为counter-app_counter-vol的卷。
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker volume ls
DRIVER VOLUME NAME
local 91b2efae88829c2de058292dcd33932db21dae9570557b5d9a5081e01fb102b5
local counter-app_counter-vol
3.4 验证部署应用¶
1、打开Docker主机浏览器输入【dock-id_addres:5000】查看应用的运行效果。 2、单击浏览器的刷新按钮，观察到计数会增加。如果使用docker-compose up &命令启动Docker Compose，终端窗口会看到包含HTTP响应码200的日志。每次刷新都会打印日志。
四、使用Docker Compose管理应用¶
4.1 使用Docker Compose启动应用¶
1、Compose文件(compose.yml或compose.yaml)所在目录视图下执行docker-compose up &命令启动Docker Compose。其中&参数代表日志回显给终端窗口。(-d参数是在后台运行)
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker-compose up &
[1] 2717
[+] Running 7/7-machine:/home/zq/Desktop/counter-app#
⠿ redis Pulled 12.1s
⠿ 213ec9aee27d Pull complete 3.2s
⠿ c99be1b28c7f Pull complete 3.4s
⠿ 8ff0bb7e55e3 Pull complete 3.8s
⠿ dedc3f029c28 Pull complete 5.6s
⠿ 820ef2f65f1b Pull complete 5.8s
⠿ 2117f9ecd795 Pull complete 6.0s
[+] Building 48.8s (10/10) FINISHED
=> [internal] load build definition from Dockerfile 0.2s
=> => transferring dockerfile: 147B 0.0s
=> [internal] load .dockerignore 0.2s
=> => transferring context: 2B 0.0s
=> [internal] load metadata for docker.io/library/python:3.6-alpine 5.3s
=> [auth] library/python:pull token for registry-1.docker.io 0.0s
=> [internal] load build context 0.1s
=> => transferring context: 30.36kB 0.0s
=> [1/4] FROM docker.io/library/python:3.6-alpine@sha256:579978dec46026 4.8s
=> => resolve docker.io/library/python:3.6-alpine@sha256:579978dec46026 0.0s
=> => sha256:579978dec4602646fe1262f02b96371779bfb0294e 1.65kB / 1.65kB 0.0s
=> => sha256:bc3447f6ba006c2268ccab840236cd1e27502a1d91 1.37kB / 1.37kB 0.0s
=> => sha256:3a9e80fa460687aa888ebe54540132662b58a3bb1a 8.08kB / 8.08kB 0.0s
=> => sha256:59bf1c3509f33515622619af21ed55bbe26d24913c 2.82MB / 2.82MB 1.6s
=> => sha256:8786870f287676cca49c1e1e5029467c087ad2 282.15kB / 282.15kB 1.8s
=> => sha256:acb0e804800ed3c10624ddeac73a6ebd3f2d6dbb 10.18MB / 10.18MB 3.2s
=> => extracting sha256:59bf1c3509f33515622619af21ed55bbe26d24913cedbca 0.2s
=> => sha256:52bedcb3e853dd5d782c46d387f2af404af9ec75c2aba3 229B / 229B 2.4s
=> => sha256:b064415ed3d75cd9bf462c4ea1a29aebe67dfe8fc7 2.21MB / 2.21MB 3.3s
=> => extracting sha256:8786870f287676cca49c1e1e5029467c087ad293b824fcd 0.2s
=> => extracting sha256:acb0e804800ed3c10624ddeac73a6ebd3f2d6dbb03970f0 0.5s
=> => extracting sha256:52bedcb3e853dd5d782c46d387f2af404af9ec75c2aba3a 0.1s
=> => extracting sha256:b064415ed3d75cd9bf462c4ea1a29aebe67dfe8fc76e672 0.4s
=> [2/4] ADD . /code 0.3s
=> [3/4] WORKDIR /code 0.1s
=> [4/4] RUN pip install -r requirements.txt 36.6s
=> exporting to image 1.1s
=> => exporting layers 1.1s
=> => writing image sha256:48da14617ca06fad52d56e7ef058c591412f0c51b93f 0.0s
=> => naming to docker.io/library/counter-app_web-fe 0.0s
Use 'docker scan' to run Snyk tests against images to find vulnerabilities and learn how to fix them
[+] Running 4/4
⠿ Network counter-app_counter-net Created 0.1s
⠿ Volume "counter-app_counter-vol" Created 0.0s
⠿ Container counter-app-redis-1 C... 0.5s
⠿ Container counter-app-web-fe-1 Created 0.6s
Attaching to counter-app-redis-1, counter-app-web-fe-1
counter-app-redis-1 | 1:C 06 Oct 2022 01:49:06.445 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
counter-app-redis-1 | 1:C 06 Oct 2022 01:49:06.445 # Redis version=7.0.5, bits=64, commit=00000000, modified=0, pid=1, just started
counter-app-redis-1 | 1:C 06 Oct 2022 01:49:06.445 # Warning: no config file specified, using the default config. In order to specify a config file use redis-server /path/to/redis.conf
counter-app-redis-1 | 1:M 06 Oct 2022 01:49:06.446 * monotonic clock: POSIX clock_gettime
counter-app-redis-1 | 1:M 06 Oct 2022 01:49:06.447 * Running mode=standalone, port=6379.
counter-app-redis-1 | 1:M 06 Oct 2022 01:49:06.447 # Server initialized
counter-app-redis-1 | 1:M 06 Oct 2022 01:49:06.447 # WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
counter-app-redis-1 | 1:M 06 Oct 2022 01:49:06.447 * Ready to accept connections
counter-app-web-fe-1 | * Serving Flask app 'app' (lazy loading)
counter-app-web-fe-1 | * Environment: production
counter-app-web-fe-1 | WARNING: This is a development server. Do not use it in a production deployment.
counter-app-web-fe-1 | Use a production WSGI server instead.
counter-app-web-fe-1 | * Debug mode: on
counter-app-web-fe-1 | * Running on all addresses.
counter-app-web-fe-1 | WARNING: This is a development server. Do not use it in a production deployment.
counter-app-web-fe-1 | * Running on http://172.18.0.2:5000/ (Press CTRL+C to quit)
counter-app-web-fe-1 | * Restarting with stat
counter-app-web-fe-1 | * Debugger is active!
counter-app-web-fe-1 | * Debugger PIN: 355-203-816
说明:默认docker-compose up会查找名为docker-compose.yml或docker-compose.yaml的Compose文件。如果Compose文件是其他文件名，需要-f参数指定文件名。
2、Compose文件(compose.yml或compose.yaml)所在目录视图下执行docker-compose up -d命令启动Docker Compose。其中-d参数代表在后台启动。
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker-compose up -d
[+] Running 3/3
⠿ Network counter-app_counter-net Created 0.1s
⠿ Container counter-app-redis-1 St... 2.7s
⠿ Container counter-app-web-fe-1 S... 3.2s
4.2 使用Docker Compose关闭应用¶
1、执行docker-compose down命令停止和关闭应用。这里注意，会留下镜像、卷和源码。
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker-compose down
[+] Running 0/0
⠋ Container counter-app-redis-1 Sto... 0.1s
[+] Running 0/2unter-app-web-fe-1 St... 0.1s
⠙ Container counter-app-redis-1 Sto... 0.2si ⠙ Container counter-app-web-fe-1 St... 0.2s
counter-app-redis-1 | 1:M 06 Oct 2022 02:32:39.369 # User requested shutdown...
counter-app-redis-1 | 1:M 06 Oct 2022 02:32:39.369 * Saving the final RDB snapshot before exiting.
[+] Running 0/2is-1 | 1:M 06 Oct 2022 02:32:39.371 * DB saved on disk
⠼ Container counter-app-redis-1 Sto... 0.5sx[+] Running 1/2unter-app-web-fe-1 St... 0.5s
[+] Running 3/3unter-app-redis-1 Rem... 0.5s
⠿ Container counter-app-redis-1 Re... 0.5s
⠿ Container counter-app-web-fe-1 R... 1.3s
⠿ Network counter-app_counter-net Removed 0.1s
[1]+ Done docker-compose up
2、执行docker-compose ps命令查看应用的当前状态。这里观察到，应用目前处于关闭状态。
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker-compose ps
NAME COMMAND SERVICE STATUS PORTS
3、执行docker image ls命令和docker volume ls命令查看卷和镜像情况。这里观察到，二者仍然存在。
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker volume ls
DRIVER VOLUME NAME
local 91b2efae88829c2de058292dcd33932db21dae9570557b5d9a5081e01fb102b5
local counter-app_counter-vol
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker image ls
REPOSITORY TAG IMAGE ID CREATED SIZE
counter-app_web-fe latest 48da14617ca0 49 minutes ago 55.5MB
redis alpine 0139e7020436 13 days ago 28.5MB
4.3 使用Docker Compose停止应用¶
1、执行docker-compose stop命令停止应用。
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker-compose stop
[+] Running 2/2
⠿ Container counter-app-redis-1 Sto... 0.3s
⠿ Container counter-app-web-fe-1 St... 0.4s
2、执行docker container ls -a命令查看全部的容器，这里观察到停止的容器仍然存在，不会删除。
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker container ls -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
e5a75ba1706e counter-app_web-fe "python app.py" 5 minutes ago Exited (0) About a minute ago counter-app-web-fe-1
e1dcbdf60223 redis:alpine "docker-entrypoint.s…" 5 minutes ago Exited (0) About a minute ago counter-app-redis-1
4.4 使用Docker Compose删除应用¶
1、执行docker-compose rm命令删除应用。这里注意，这只会删除应用相关的容器和网络，但是不会删除卷、镜像、应用源码。
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker-compose rm
? Going to remove counter-app-web-fe-1, counter-app-redis-1 Yes
[+] Running 2/0
⠿ Container counter-app-redis-1 Rem... 0.0s
⠿ Container counter-app-web-fe-1 Re... 0.0s
2、执行docker container ls -a命令查看全部的容器，这里观察到容器删除完成。
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker container ls -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
4.5 使用Docker Compose重启应用¶
1、执行docker-compose restart命令重启应用。这里注意，重启应用的条件是停止应用，而不是删除应用，换句话说，删除应用没办法重启应用。
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker-compose restart
[+] Running 2/2
⠿ Container counter-app-web-fe-1 St... 1.7s
⠿ Container counter-app-redis-1 Sta... 0.8s
2、执行docker-compose ps命令查看应用的当前状态。这里观察到，应用目前处于关闭状态。
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker-compose ps
NAME COMMAND SERVICE STATUS PORTS
counter-app-redis-1 "docker-entrypoint.s…" redis running 6379/tcp
counter-app-web-fe-1 "python app.py" web-fe running 0.0.0.0:5000->5000/tcp, :::5000->5000/tcp
五、使用Docker Compose部署、管理应用命令¶
1、Compose文件(compose.yml或compose.yaml)所在目录视图下执行docker-compose up &命令启动Docker Compose。其中&参数代表日志回显给终端窗口。(-d参数是在后台运行)
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker-compose up &
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker-compose up -d
说明:默认docker-compose up会查找名为docker-compose.yml或docker-compose.yaml的Compose文件。如果Compose文件是其他文件名，需要-f参数指定文件名。
2、执行docker network ls命令查看网络。这里观察到生成名为counter-app_counter-net的网络。
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker network ls
3、执行docker volume ls命令查看卷，这里观察到生成名为counter-app_counter-vol的卷。
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker volume ls
4、执行docker-compose down命令停止和关闭应用。这里注意，会留下镜像、卷和源码。
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker-compose down
5、执行docker-compose ps命令查看应用的当前状态。这里观察到，应用目前处于关闭状态。
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker-compose ps
6、执行docker-compose restart命令重启应用。这里注意，重启应用的条件是停止应用，而不是删除应用，换句话说，删除应用没办法重启应用。
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker-compose restart
7、执行docker volume inspect counter-app_counter-vol | grep Mount命令查看卷位于Docker主机的什么位置。
root@zq-virtual-machine:/home/zq/Desktop/counter-app# docker volume inspect counter-app_counter-vol | grep Mount
"Mountpoint": "/var/lib/docker/volumes/counter-app_counter-vol/_data"