Will data be lost after the docker container is restarted?

Data will be lost after the docker container is restarted; however, volume or "data container" can be used to achieve data persistence. After the container is closed, "-v" or "-volumes-from" can be used to reuse the previous For data, docker can also mount the host disk directory to permanently store data.

The operating environment of this tutorial: linux7.3 system, docker version 19.03, Dell G3 computer.

Will the data be lost after the docker container is restarted?

Yes, when you use docker to deploy web applications or mysql databases, you will find that after the container is restarted, the logs or databases generated during the running of the container The data will be cleared.

If you want data persistence, you need to use a volume or data container, so that you can reuse the previous data through -v or --volumes-from after the container is closed. Docker mounts the host disk directory to permanently store data.

Execute Docker Volume when creating a container

Use the docker run command to run a Docker container, use the image ubuntu/nginx, and mount the local directory /tmp/source to Container directory/tmp/destination

docker run -itd --volume /tmp/source:/tmp/destination --name test ubuntu/nginx bash

Created a Docker container based on the ubuntu/nginx image. The name of the specified container is test, specified by the ––name option.

Docker Volume is specified by the ––volume (can be abbreviated as -v) option. The /tmp/source directory of the host corresponds to the /tmp/destination directory in the container.

View Docker Volume

Use the docker inspect command to view the detailed information of the Docker container:

docker inspect --format='{{json .Mounts}}'test | python -m json.tool[{"Destination": "/tmp/destination",
"Mode": "","Propagation": "","RW": true,"Source": "/tmp/source","Type": "bind"}]

Use the --format option to select View the required container information. .Mount is the Docker Volume information of the container.

python -m json.tool can format and display the output json string. Source represents a directory on the host, which is /tmp/source . Destination is the directory in the container, which is /tmp/destination.

Local files can be synchronized to the container

Create a new hello.txt file in the local/tmp/source directory

touch /tmp/source/hello.txtls /tmp/source/hello.txt

hello.txt file Visible in the container/tmp/destination/ directory

Use the docker exec command to execute commands in the container.

docker exectest ls /tmp/destination/hello.txt

So modifications to the directory /tmp/source/ on the host machine can be synchronized to the container directory /tmp/destination/.

Container files can be synchronized to the host machine

Create a new world.txt file in the container/tmp/destination directory

docker exec test touch /tmp/destination/world.txtdocker exec test ls /tmp/destination/hello.txtworld.txt

The world.txt file is in Visible in the host/tmp/source/ directory

ls /tmp/source/hello.txt world.txt

Recommended learning: "docker video tutorial"

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