How to modify Docker file mapping

Docker is currently one of the most popular container technologies, allowing developers to develop and test applications in a closed environment. Docker file mapping is an important concept in Docker, which allows files or directories on the host to be mapped to files or directories in the Docker container, so that applications in the container can access resources on the host. In actual use, we may need to modify the Docker file mapping to meet different needs. This article will introduce the basic concepts of Docker file mapping and how to modify Docker file mapping.

1. The basic concept of Docker file mapping

Docker file mapping refers to mapping files or directories on the host to files or directories in the Docker container. Through file mapping, Docker containers can access resources on the host, such as configuration files, log files, etc. In Docker, file mapping is achieved through the -v parameter. The -v parameter has the following uses:

1. Map a directory on the host to a directory on the container:

docker run -v /path/on/host:/path/on/container image-name

This command will The /path/on/host directory on the host is mapped to the /path/on/container directory within the container.

2. Map the current working directory to a directory in the container:

docker run -v $(pwd):/path/on/container image-name

This command maps the current working directory to /path/on/ within the container container directory.

3. Map a data volume to a directory in the container:

docker run -v volume-name:/path/on/container image-name

This command maps the data volume volume-name to a directory in the container /path/on/containerDirectory.

2. Modify Docker file mapping

In actual applications, we may need to modify Docker file mapping. For example, when we run an application in a Docker container, we need to place the configuration file in a specific directory on the host. In this case, we need to modify the file mapping so that the directory on the host is mapped to the directory in the container. Let's take a look at how to modify Docker file mapping.

1. Stop the Docker container

First, we need to stop the running Docker container. You can use the following command to stop a Docker container:

docker stop container-id

where container-id is the ID of the Docker container.

2. Modify Docker file mapping

Next, we need to modify the Docker file mapping to map the required directories into the Docker container. Modifying Docker file mapping requires modifying the original Docker command. For example, the original Docker command is:

docker run -d -p 8080:8080 -v /var/lib/docker/volumes/app-data/_data:/data app:latest

The above command maps the /var/lib/docker/volumes/app-data/_data directory to /data in the Docker container Table of contents. Now we need to modify it to:

docker run -d -p 8080:8080 -v /home/user/app-data:/data app:latest

where /home/user/app-data is the directory we want to map.

3. Start the Docker container

After modifying the Docker command, we need to restart the Docker container. You can use the following command to start the modified Docker container:

docker start container-id

where container-id is the ID of the Docker container.

After modifying the Docker file mapping, we can enter the Docker container to see if the directory we need is correctly mapped. You can use the following command to enter the Docker container:

docker exec -it container-id /bin/bash

where container-id is the ID of the Docker container. After entering the Docker container, we can use the cd command to enter the /data directory to check whether the files in it are consistent with the files on the host.

Summary:

In this article, we introduced the basic concepts of Docker file mapping and demonstrated how to modify Docker file mapping. In actual use, Docker file mapping needs to be modified according to different needs to meet the needs of the application. For beginners, mastering the relevant knowledge of Docker file mapping can help them better use Docker technology.

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