#假设通过如下命令启动了一个容器
docker run -d --name mysql-p 3306:3306-e MYSQL_ROOT_PASSWORD=123456--restart=alwaysmysql:5.5 --character-set-server=utf8

#如何通过容器名得知启动参数
[root@jenkins ~]# docker inspect mysql_cdh
[
  {
    "Id": "fbc3fba81b57bc5b5871746098b5f1f7ef0ed7716a786584a5effbb88ba156e6",
    "Created": "2019-09-25T01:43:37.720505875Z",
    "Path": "docker-entrypoint.sh",
    "Args": [
      "--character-set-server=utf8"
    ],

 "HostConfig": {
      "Binds": [
        "mysql-data:/var/lib/mysql"
      ],
      "ContainerIDFile": "",
      "LogConfig": {
        "Type": "json-file",
        "Config": {}
      },
      "NetworkMode": "default",
      "PortBindings": {
        "3306/tcp": [{  "HostIp": "",  "HostPort": "3306"}
        ]
      },
      "RestartPolicy": {
        "Name": "always",
        "MaximumRetryCount": 0
      },
  
"Mounts": [
      {
        "Type": "volume",
        "Name": "mysql-data",
        "Source": "/var/lib/docker/volumes/mysql-data/_data",
        "Destination": "/var/lib/mysql",
        "Driver": "local",
        "Mode": "z",
        "RW": true,
        "Propagation": ""
      }
    ],

[root@master ~]# docker image inspect nginx |tail -n 22
    "GraphDriver": {
      "Data": {
        "LowerDir": "/var/lib/docker/overlay2/bf20cf788cc053f00ff1467525d50e19bd1cf07a2167f72511bdfcb28918a472/diff:/var/lib/docker/overlay2/317d80bb7ae58ed288be9ebd84aeb5b4b3a1c06f3211f5d1f32d89b629d1876e/diff",
        "MergedDir": "/var/lib/docker/overlay2/7782d0eb292fdc8bbd73bf9bae2d65468e8aba0bcd6baed55ac348618b80ae16/merged",
        "UpperDir": "/var/lib/docker/overlay2/7782d0eb292fdc8bbd73bf9bae2d65468e8aba0bcd6baed55ac348618b80ae16/diff",
        "WorkDir": "/var/lib/docker/overlay2/7782d0eb292fdc8bbd73bf9bae2d65468e8aba0bcd6baed55ac348618b80ae16/work"
      },
      "Name": "overlay2"
    },

#1, 启动容器
[root@master ~]# docker run -d --name nginx2 nginx
a9c9f31cdccf13c3385f3de33443325d2e14d69458e6d679e54c8cf9e5ff24c8

#2, 获取容器id
[root@master ~]# docker inspect nginx2 | grep -i id 
[root@master ~]# docker inspect nginx2 | grep -i id 
    "Id": "a9c9f31cdccf13c3385f3de33443325d2e14d69458e6d679e54c8cf9e5ff24c8",
      "Pid": 2069,
    "ExecIDs": null,
      "ContainerIDFile": "",
  
#查看容器临时文件--每次创建时随机生成的文件(容器层)
[root@master ~]# docker inspect nginx2 | grep -i path
    "Path": "nginx",
    "ResolvConfPath": "/var/lib/docker/containers/a9c9f31cdccf13c3385f3de33443325d2e14d69458e6d679e54c8cf9e5ff24c8/resolv.conf",
    "HostnamePath": "/var/lib/docker/containers/a9c9f31cdccf13c3385f3de33443325d2e14d69458e6d679e54c8cf9e5ff24c8/hostname",
    "HostsPath": "/var/lib/docker/containers/a9c9f31cdccf13c3385f3de33443325d2e14d69458e6d679e54c8cf9e5ff24c8/hosts",
    "LogPath": "/var/lib/docker/containers/a9c9f31cdccf13c3385f3de33443325d2e14d69458e6d679e54c8cf9e5ff24c8/a9c9f31cdccf13c3385f3de33443325d2e14d69458e6d679e54c8cf9e5ff24c8-json.log",
 
#通过容器id, 查找容器数据存放目录： /var/lib/docker/overlay2/容器id
######
#对比上面的“镜像层：文件存放路径”，可以看到 :容器通过LowerDir 挂载的方式，映射了镜像层的文件
######
[root@master ~]# docker inspect nginx2 | grep -i dir
        "LowerDir": "/var/lib/docker/overlay2/d37ff828e63081be6fcfefc73891e7b455596cb921c8021fbf9571f330c0599b-init/diff:/var/lib/docker/overlay2/7782d0eb292fdc8bbd73bf9bae2d65468e8aba0bcd6baed55ac348618b80ae16/diff:/var/lib/docker/overlay2/bf20cf788cc053f00ff1467525d50e19bd1cf07a2167f72511bdfcb28918a472/diff:/var/lib/docker/overlay2/317d80bb7ae58ed288be9ebd84aeb5b4b3a1c06f3211f5d1f32d89b629d1876e/diff",
        "MergedDir": "/var/lib/docker/overlay2/d37ff828e63081be6fcfefc73891e7b455596cb921c8021fbf9571f330c0599b/merged",
        "UpperDir": "/var/lib/docker/overlay2/d37ff828e63081be6fcfefc73891e7b455596cb921c8021fbf9571f330c0599b/diff",
        "WorkDir": "/var/lib/docker/overlay2/d37ff828e63081be6fcfefc73891e7b455596cb921c8021fbf9571f330c0599b/work"

[root@docker d93185e3a0....2e544ccfa]# pwd
/var/lib/docker/containers/d93185e3a0....2e544ccfa
[root@docker d93185e3a0....2e544ccfa]# cat hostconfig.json 
{"Binds":["/dockersuperset:/home/superset"],"ContainerIDFile":"",
"LogConfig":{"Type":"json-file","Config":{}},"NetworkMode":"default",
"PortBindings":{"8088/tcp":[{"HostIp":"","HostPort":"8099"}]}......

# 进入镜容器文件存储目录， 修改配置文件
[root@master ~]# cd /var/lib/docker/overlay2/d37ff828e63081be6fcfefc73891e7b455596cb921c8021fbf9571f330c0599b
[root@master d37ff828e63081be6fcfefc73891e7b455596cb921c8021fbf9571f330c0599b]# ls
diff link lower merged work

[root@master d37ff828e63081be6fcfefc73891e7b455596cb921c8021fbf9571f330c0599b]# ls diff/run/
nginx.pid
[root@master d37ff828e63081be6fcfefc73891e7b455596cb921c8021fbf9571f330c0599b]# ls diff/var/cache/nginx/
client_temp fastcgi_temp proxy_temp scgi_temp uwsgi_temp

[root@master d37ff828e63081be6fcfefc73891e7b455596cb921c8021fbf9571f330c0599b]# ls merged/
bin/    dev/    etc/    lib/    media/   opt/    root/    sbin/    sys/    usr/    
boot/    .dockerenv home/    lib64/   mnt/    proc/    run/    srv/    tmp/    var/    

[root@master d37ff828e63081be6fcfefc73891e7b455596cb921c8021fbf9571f330c0599b]# ls merged/etc/nginx/
conf.d fastcgi_params koi-utf koi-win mime.types modules nginx.conf scgi_params uwsgi_params win-utf

[root@master d37ff828e63081be6fcfefc73891e7b455596cb921c8021fbf9571f330c0599b]# head merged/etc/nginx/nginx.conf 
user nginx;
worker_processes 1;

#在此处修改配置文件，把user nginx; worker_process 1; 这两行的分号去掉，看容器里面的配置是否更改
[root@master d37ff828e63081be6fcfefc73891e7b455596cb921c8021fbf9571f330c0599b]# head merged/etc/nginx/nginx.conf -n 3
user nginx
worker_processes 1

#登陆容器，查看修改的配置： 验证是否生效
[root@master d37ff828e63081be6fcfefc73891e7b455596cb921c8021fbf9571f330c0599b]# docker exec -it nginx2 bash
root@a9c9f31cdccf:/# head /etc/nginx/nginx.conf -n 3
user nginx
worker_processes 1

a, 重建/var/lib/docker目录
#备份数据到新的存放路径
service docker stop
mkdir /docker.bak
mv /var/lib/docker/* /docker.bak

#创建软连接
mkdir /home/docker-data
mv /docker.bak/* /home/docker-data/ && rmdir /docker.bak
ln -s  /home/docker-data /var/lib/docker
b, 修改配置
vi /usr/lib/systemd/system/docker.service 
ExecStart=/usr/bin/dockerd --graph /new-path/docker 

#reload配置文件 
systemctl daemon-reload 
#重启docker 
systemctl restart docker.service

cat << EOF /etc/docker/daemon.json
{
  "data-root": "/mnt/docker-data"
}
EOF
systemctl restart docker

ExecStart=/usr/bin/dockerd --data-root='/home/docker'
systemctl daemon-reload
systemctl restart docker