docker file storage path get container startup command operation

2021-09-16 08:34:15
OfStack

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


# Suppose you started with the following command 1 Containers 
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 Startup Parameters by 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. Mirror 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,  Startup container 
[root@master ~]# docker run -d --name nginx2 nginx
a9c9f31cdccf13c3385f3de33443325d2e14d69458e6d679e54c8cf9e5ff24c8

#2,  Get 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 every time they are created ( Container layer )
[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 "Mirror Layer: File Storage Path", you can see that  : Container passing LowerDir  The way to mount, mapping the files of the mirror layer 
######
[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 the 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,   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 to put user nginx; worker_process 1;  Remove the semicolons in these two lines to see if the configuration in the container has changed 
[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,  Reconstruction /var/lib/docker Directory 
# Back up data to a 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 Configuration file  
systemctl daemon-reload 
# Restart docker 
systemctl restart docker.service

Additional knowledge: Docker specifies the data storage directory

Docker specifies the storage directory (the original parameter-graph has expired. )

Method 1

1. Configure the/etc/docker/daemon. json in the Docker configuration file

The following command is added when there is no content in the daemon. json file. If there is content, you need to


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

Method 2

2. Configure in startup parameters

vim /usr/lib/systemd/system/docker.service

Add the following after EXECStart inside:


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