Preface
I don’t know what is Docker volumes!
Okay docker! What is this hell the docker volumes before know this thing I have a problem using docker because docker we know run a container-container also known as database container.
And that container has a f***** virtual file system in /var/lib/<image>/data. So, I cannot access, see directory folder without logged in to container.
I tell you that your project or your container has a virtual data or we can call it a non-persistence data which is not available after fully closing (delete) the container because the data stored in a virtual file system in a spesific container.
Example
MySQL phpmyadmin
It means, in this case I need persistence local data for running the project with docker. in this case I use example from mysql and phpmyadmin. Look at this YAML file.
version: '3.7'
services:
db:
image: mysql:latest
container_name: chatphpDB
restart: always
ports:
- '6603:3306'
environment:
MYSQL_ROOT_PASSWORD: admin
service:
volumes:
- <your_dir_path>:/etc/mysql/conf.d
- <your_dir_path>:/var/lib/mysql
app:
depends_on:
- db
image: phpmyadmin/phpmyadmin
container_name: phpmyadmin
restart: always
ports:
- '8889:80'
environment:
PMA_HOST: db
I’m focus to mysql services to take an examples about Docker Volumes
When you install a MySQL container, you will find its configuration options in the /etc/mysql/my.cnf and the data storage directory. So, I need mount my external directory inside the container.
/etc/mysql/conf.d = MySQL config file /var/lib/mysql = Data storage
How to know that? let’s inspect the container details!
$ docker inspect chatphpDB
...
"Mounts": [
{
"Type": "volume",
"Name": "05ea8c6cc5abbeba7d6962f108b3633d1011c272589a6b27fda1330e7971d9da",
"Source": "/var/snap/docker/common/var-lib-docker/volumes/05ea8c6cc5abbeba7d6962f108b3633d1011c272589a6b27fda1330e7971d9da/_data",
"Destination": "/var/lib/mysql",
"Driver": "local",
"Mode": "rw",
"RW": true,
"Propagation": ""
},
...
Look! the mysql-data are stored in virtual File System (FS) container /var/lib/mysql
Simple directory mounts
The simplest approach is mounting arbitrary host directory to container’s FS. My expectation is have a writable mounting system in my home folder.
Docker run command
docker run -d \
-v /home/bima/Workspace/Project_iseng_PHP/Chat_with_php_jquery_ajax/docker/chatphpDB/conf.d:/etc/mysql/conf.d \
-v /home/bima/Workspace/Project_iseng_PHP/Chat_with_php_jquery_ajax/docker/chatphpDB/:/var/lib/mysql \
--name chatphpDB \
mysql
Docker compose
create docker-compose.yml
services:
<application>:
<some option>
...
volumes:
- /home/bima/Workspace/Project_iseng_PHP/Chat_with_php_jquery_ajax/docker/chatphpDB/conf.d:/etc/mysql/conf.d
- /home/bima/Workspace/Project_iseng_PHP/Chat_with_php_jquery_ajax/docker/chatphpDB/:/var/lib/mysql
Run with docker-compose up -d
$ docker-compose up -d
Removing chatphpDB
Recreating 3142d4446c38_chatphpDB ...
WARNING: Service "db" is using volume "/var/lib/mysql" from the previous container. Host mapping "/home/bima/Workspace/Project_iseng_PHP/Chat_with_php_jquery_ajax/dockRecreating 3142d4446c38_chatphpDB ... done
phpmyadmin is up-to-date
Now, we can inspect to know status of chatphpDB container
$ docker inspect chatphpDB
[
{
"Id": "b3bdd7c099e8e82f5e4c7cb24815f2bdfa4c9c1884c2866de00419d015a2e563",
"Created": "2020-09-21T19:02:18.444355762Z",
"Path": "docker-entrypoint.sh",
"Args": [
"mysqld"
],
"State": {
"Status": "running",
"Running": true,
"Paused": false,
"Restarting": false,
"OOMKilled": false,
"Dead": false,
"Pid": 4601,
"ExitCode": 0,
"Error": "",
"StartedAt": "2020-09-21T19:02:20.395048624Z",
"FinishedAt": "0001-01-01T00:00:00Z"
},
...
"Mounts": [
{
"Type": "volume",
"Name": "05ea8c6cc5abbeba7d6962f108b3633d1011c272589a6b27fda1330e7971d9da",
"Source": "/var/snap/docker/common/var-lib-docker/volumes/05ea8c6cc5abbeba7d6962f108b3633d1011c272589a6b27fda1330e7971d9da/_data",
"Destination": "/var/lib/mysql",
"Driver": "local",
"Mode": "rw",
"RW": true,
"Propagation": ""
},
{
"Type": "bind",
"Source": "/home/bima/Workspace/Project_iseng_PHP/Chat_with_php_jquery_ajax/docker/chatphpDB/conf.d",
"Destination": "/etc/mysql/conf.d",
"Mode": "rw",
"RW": true,
"Propagation": "rprivate"
}
volumes…. it’s working!
...
"Source": "/home/bima/Workspace/Project_iseng_PHP/Chat_with_php_jquery_ajax/docker/chatphpDB/conf.d",
"Destination": "/etc/mysql/conf.d",
...
Examine my case
Whooops.. I set two volumes to mount, but the one not changes.. we will back again (^_^)
See MySQL database storage in virtual file system in my container! login with command docker exec -t -i chatphpDB /bin/bash
root@b3bdd7c099e8:/var/lib/mysql# ls
'#ib_16384_0.dblwr' auto.cnf binlog.000004 binlog.000008 client-cert.pem ib_logfile1 mysql.ibd server-cert.pem undo_002
'#ib_16384_1.dblwr' binlog.000001 binlog.000005 binlog.index client-key.pem ibdata1 performance_schema server-key.pem
'#innodb_temp' binlog.000002 binlog.000006 ca-key.pem ib_buffer_pool ibtmp1 private_key.pem sys
asd binlog.000003 binlog.000007 ca.pem ib_logfile0 mysql public_key.pem undo_001
Then see what in my external mounted file. not showing a mounted data directory from /var/lib/mysql
$ pwd
docker/chatphpDB/
$ ls
conf.d/
How to solve my case
Read from this article - mysql docker container - mysql docker containers: understanding basics