Will data be lost after docker restarts?

When you use Docker to deploy web applications or mysql databases, you will find that when the container is restarted, the logs or database data generated during the running of the container will be cleared.

Solution:

Docker can permanently store data by mounting the host disk directory.

1. 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 the 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.

2. 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 selectively 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 the directory on the host, that is, /tmp/source.

Destination is the directory in the container, that is, /tmp/destination.

3. 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

The hello.txt file is 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/.

4. 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 visible in the host/tmp/source/ directory

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

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