docker（十二）：docker持久化

一、实现功能

当关闭docker容器时，其内部的文件会消失。然后重新启动docker，则原始保存文件会丢失。所以，需要做一定的持久化，即第一次关闭的时候，把文件保存到本地磁盘，进而第二次打开docker容器，可以获得之前保存的数据，不至于丢失。

二、docker volume持久化实现

1.运行mysql容器

[root@docker-node1 ~]# sudo docker run -d --name mysql1 -e MYSQL_ALLOW_EMPTY_PASSWORD=true mysql
cfb5287addde854587c74311788c3c40846f1b68c269e48ce490bb7a9ca094db
[root@docker-node1 ~]# docker ps
CONTAINER ID        IMAGE                                  COMMAND                  CREATED             STATUS              PORTS                                                                                                                                                                                                                                                                                                                                                                                NAMES
cfb5287addde        mysql                                  "docker-entrypoint.s…"   5 seconds ago       Up 5 seconds        3306/tcp, 33060/tcp                                                                                                                                                                                                                                                                                                                                                                  mysql1

2.查看生成volume具体信息
（1）查看生成volume

[root@docker-node1 ~]# sudo docker volume ls
DRIVER              VOLUME NAME
local               715be444d8a88c937f0c9ff47147b445a3144069fa94db9bb85129da6ad496a3

（2）查看volume具体细节信息

sudo docker volume inspect [volume name] (上一步骤）
实例
[root@docker-node1 ~]# sudo docker volume inspect 715be444d8a88c937f0c9ff47147b445a3144069fa94db9bb85129da6ad496a3
[
    {
        "CreatedAt": "2019-06-28T21:39:18Z",
        "Driver": "local",
        "Labels": null,
        "Mountpoint": "/var/lib/docker/volumes/715be444d8a88c937f0c9ff47147b445a3144069fa94db9bb85129da6ad496a3/_data",
        "Name": "715be444d8a88c937f0c9ff47147b445a3144069fa94db9bb85129da6ad496a3",
        "Options": null,
        "Scope": "local"
    }
]

3.创建第二个mysql容器mysql2

sudo docker run -d --name mysql2 -e MYSQL_ALLOW_EMPTY_PASSWORD=true mysql

4.查看

（1）查看生成volume

[root@docker-node1 ~]# docker volume ls
DRIVER              VOLUME NAME
local               715be444d8a88c937f0c9ff47147b445a3144069fa94db9bb85129da6ad496a3
local               76863a4ee8f28b072fa2a6fe6fc334522af7e694e9aca98cfa16862629bae938

（2）查看volume具体细节信息

[root@docker-node1 ~]# docker volume inspect 76863a4ee8f28b072fa2a6fe6fc334522af7e694e9aca98cfa16862629bae938
[
    {
        "CreatedAt": "2019-06-28T21:45:54Z",
        "Driver": "local",
        "Labels": null,
        "Mountpoint": "/var/lib/docker/volumes/76863a4ee8f28b072fa2a6fe6fc334522af7e694e9aca98cfa16862629bae938/_data",
        "Name": "76863a4ee8f28b072fa2a6fe6fc334522af7e694e9aca98cfa16862629bae938",
        "Options": null,
        "Scope": "local"
    }
]

5.关闭两个容器，volume不会删除

sudo docker stop mysql1 mysql2
sudo docker rm mysql1 mysql2
查看
sudo docker ps -a
查看volume，依旧存在
[root@docker-node1 ~]# sudo docker volume ls
DRIVER              VOLUME NAME
local               715be444d8a88c937f0c9ff47147b445a3144069fa94db9bb85129da6ad496a3
local               76863a4ee8f28b072fa2a6fe6fc334522af7e694e9aca98cfa16862629bae938

6.删除刚刚新建的volume

sudo docker volume rm [volume name]
查看
[root@docker-node1 ~]# docker volume ls
DRIVER              VOLUME NAME

7.重新创建mysql容器，赋予volume简单名称

ps：mysql产生数据都会产生到这个目录内

sudo docker run -d -v mysql:/var/lib/mysql --name mysql1 -e MYSQL_ALLOW_EMPTY_PASSWORD=true mysql
查看volume
sudo docker volume ls
[root@docker-node1 labs]# sudo docker volume ls
DRIVER              VOLUME NAME
local               mysql

8.验证持久化

（1）写入数据到mysql1容器中，创建数据库docker

sudo docker exec -it mysql1 /bin/bash

输入
mysql -u root

创建database
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
4 rows in set (0.06 sec)

mysql> create database docker;
Query OK, 1 row affected (0.04 sec)
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| docker             |
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
5 rows in set (0.01 sec)

（2）删除mysql1，创建mysql2

[root@docker-node1 labs]# docker rm -f mysql1
mysql1

创建
sudo docker run -d -v mysql:/var/lib/mysql --name mysql2 -e MYSQL_ALLOW_EMPTY_PASSWORD=true mysql

进入
sudo docker exec -it mysql2 /bin/bash
查看

输入
mysql -u root

创建database
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| docker             |
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
5 rows in set (0.04 sec)

三、bind mounting持久化实现

1.实现原理

即实现docker宿主虚拟机的目录和docker目录同步

2.进入目录，依据Dockerfile新建image

（1）找到Dockerfile位置

cd /home/vagrant/labs/labs/labs/docker-nginx

（2）Dockerfile

# this same shows how we can extend/change an existing official image from Docker Hub

FROM nginx:latest
# highly recommend you always pin versions for anything beyond dev/learn

WORKDIR /usr/share/nginx/html
# change working directory to root of nginx webhost
# using WORKDIR is prefered to using 'RUN cd /some/path'

COPY index.html index.html

# I don't have to specify EXPOSE or CMD because they're in my FROM

（3）新建image

docker build -t nginx:latest ./

3.运行nginx

docker run -d -v $(pwd):/usr/share/nginx/html -p 80:80 --name web nginx

4.进入容器

docker exec -it web /bin/bash

新建文件，然后退出
touch test2.txt
exit

5.查看docker宿主机上对应目录会同步修改文件

[vagrant@docker-node1 docker-nginx]$ pwd
/home/vagrant/labs/labs/labs/docker-nginx
[vagrant@docker-node1 docker-nginx]$ ls
Dockerfile  index.html  test2.txt

6.在宿主机上修改test2.txt，进入docker查看

docker exec -it web /bin/bash
依旧会有修改内容，即二者是同步的
vi test2.txt

四、持久化在生产中应用

1.在目录下，新建image

[root@docker-node1 flask-skeleton]# pwd
/home/vagrant/labs/labs/labs/flask-skeleton

docker build -t flask-skeleton:latest ./

2.运行

docker run -d -p 80:5000 --name flask flask-skeleton

3.查看网页

192.168.205.10:80

4.同步目录本地和容器中目录

docker run -d -p 80:5000 -v $(pwd):/skeleton --name flask flask-skeleton

5.打开浏览器

192.168.205.10:80

6.打开linux源码

修改skeleton/client/template/main/home.html
修改内容：
welcome为
welcome to dockerworld！
重新查看网页