How to get start command of container

• The container has already been created. How to know its startup parameters (where to mount the data)

#Suppose you start a container with the following command
docker run  -d  --name mysql\
-p 3306:3306\
-e MYSQL_ROOT_PASSWORD=123456\
--restart=always\
mysql:5.5 --character-set-server=utf8

#How to know the startup parameters by the container name
[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": ""
            }
        ],

1. Image layer: file storage path

[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"
        },

2. Container layer: file storage path

#1. Start the container
[root@master ~]# docker run -d --name nginx2 nginx
a9c9f31cdccf13c3385f3de33443325d2e14d69458e6d679e54c8cf9e5ff24c8

#2. Get the container id
[root@master ~]# docker inspect nginx2  | grep -i id 
[root@master ~]# docker inspect nginx2  | grep -i id 
        "Id": "a9c9f31cdccf13c3385f3de33443325d2e14d69458e6d679e54c8cf9e5ff24c8",
            "Pid": 2069,
        "ExecIDs": null,
            "ContainerIDFile": "",
			
#View container temporary files -- randomly generated files (container layer) each time they are created
[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",
 
#Through the container id, find the container data storage directory: / var/lib/docker/overlay2 / container id
######
#Compared with the above "image layer: file storage path", we can see that the container maps the files of image layer through the way of LowerDir mounting
######
[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"

Modify container port day after tomorrow

Through the container layer file, find the configuration file hostconfig.json, and modify the port mapped by the container

[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"}]}......

3. Enter the mirror container file storage directory and modify the configuration file

# Enter the mirror container file storage directory and modify the configuration file
[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;

#Modify the configuration file here, and remove the semicolon of user nginx; worker ﹣ process 1; to see if the configuration in the container changes
[root@master d37ff828e63081be6fcfefc73891e7b455596cb921c8021fbf9571f330c0599b]# head merged/etc/nginx/nginx.conf -n 3
user  nginx
worker_processes  1

#Log in to the container to view the modified configuration: verify whether it is effective
[root@master d37ff828e63081be6fcfefc73891e7b455596cb921c8021fbf9571f330c0599b]# docker exec -it nginx2 bash
root@a9c9f31cdccf:/# head /etc/nginx/nginx.conf -n 3
user  nginx
worker_processes  1

4. Modify the default storage path

a. Rebuild / var/lib/docker directory

#Backup data to new storage path
service docker stop
mkdir /docker.bak
mv /var/lib/docker/*  /docker.bak

#Create a soft connection
mkdir /home/docker-data
mv /docker.bak/*  /home/docker-data/ && rmdir /docker.bak
ln -s   /home/docker-data  /var/lib/docker

b. Modify configuration

vi /usr/lib/systemd/system/docker.service  
ExecStart=/usr/bin/dockerd --graph /new-path/docker 

#reload profile 
systemctl daemon-reload 
#Restart docker 
systemctl restart docker.service