How to restore docker container data

The project test environment database data is lost, so I would like to record it. It was installed using Docker at the time, thinking it would be used temporarily for a period of time and not be persistent. Suddenly the day before yesterday, the docker log was full, and my colleague wanted to clean up the log and used the following command:

docker system prune

As a result, the MySQL container was normally in a stopped state at the time, but it was killed all of a sudden. The data we backed up was from March, which was terrible. Then various studies began to resume.

Then I went to the official documentation to study what this command does. docker system prune used above means:

Remove all unused containers, networks, images (both dangling and unreferenced), and optionally, volumes.

Remove all unused containers, networks, images (dangling and unreferenced images), and optionally, volumes.

By default, volumes are not removed to prevent important data from being deleted if there is currently no container using the volume. Use the --volumes flag when running the command to prune volumes as well:

By default, if there are no containers currently using the volume, the volume will not be deleted to prevent deletion of important data. You can also use the --volumes flag when running the command to prune volumes:

Now I feel relieved. Fortunately, the data volume has not been deleted. We can use the data volume to recover the data. Next, I will record my recovery plan.

1. Find the data volume location

The data volume directory is under /var/lib/docker/volumes . Each container will have a folder under this directory. If the container still exists, we can use docker inspect 容器ID to view the data volume location. Now the container has been deleted, what can we do? We can only look for them one by one. Generally, there will be a _data directory under the MySQL container data volume directory, which will display the folders of each database, and finally found it.

This cxhello is our test library, now we can restore the data.

2. Recovery

Use docker volume create 數據卷名字command to create a new volume, and docker volume ls to view the list of volumes.

Note: When using a data volume for mounting, the data volume must be an empty directory, that is, it cannot contain any data.

Then create the container

docker run -d -p 3309:3306 -v mysqldata:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=123456 --name huifu mysql:5.7

Before recovering data, you need to delete the associated content in the newly created data volume, and then copy the previous data volume content to the current data volume for data recovery.

cd /var/lib/docker/volumes/mysqldata/_data/
rm -f *
rm -f -R *

Copy content to data volume

cd /var/lib/docker/volumes/1db16a9dfdf3442b117ebc2ec11df5df4db717cfd567c77fa0a49905a9652fa0/_data/
cp -R * /var/lib/docker/volumes/mysqldata/_data/

At this point, the database data recovery is complete. Enter the restored container to view

References

https://docs.docker.com/engine/reference/commandline/system_prune/

https://www.cnblogs.com/cheyunhua/p/13433400.html

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