How to softly connect to the host directory in a docker container

As a technology for rapid deployment and management of applications, Docker has been widely used in development and production environments. When using Docker, we often need to map the host directory to the inside of the Docker container so that the container can read and write files on the host.

However, in some cases, we need to soft-connect a directory or file in the Docker container to a directory or file on the host machine. This is very useful in practical applications, such as using soft connections to share a code base between the host and the container, or allowing the container to access a certain hardware device on the host.

This article will introduce how to implement a soft connection to the host directory inside the Docker container.

1. Preparation

In order to implement a soft connection to the host directory inside the Docker container, we need to first share the directory on the Docker host to the inside of the Docker container. Here we take the /data directory of the shared host as an example.

First, create a directory /data on the host, create a file test.txt in the directory, and then write some test content in the file . Next, we need to map the host's /data directory to a directory inside the Docker container when starting the Docker container, such as /container_data.

Assume that we have started a Docker container named test through the docker run command and mapped the host's /data directory Arrived in the /container_data directory inside the container. Now we can check the /container_data directory inside the Docker container to verify that the share has been set up correctly.

2. Create a soft connection inside the Docker container

After completing the sharing settings, we can create a soft connection inside the Docker container and add a directory or file in the container Link to a directory or file on the host machine. Here we take the soft connection of /container_data/test.txt in the container to /data/test.txt on the host as an example.

Run the following command in the Docker container:

ln -s /container_data/test.txt /data/test.txt

This command will create a soft connection /data/test.txt in the container and point it to /data/test.txt on the host machine. We can verify whether the soft connection has been created correctly inside the Docker container:

ls -l /data/test.txt

This command will output the following:

lrwxrwxrwx 1 root root 24 Mar 17 10:00 /data/test.txt -> /container_data/test.txt

As you can see, the -&gt in the output result The ; symbol indicates that /data/test.txt is softly connected to /container_data/test.txt.

3. Test whether the soft link is working properly

After confirming that the soft link has been correctly created inside the Docker container, we can test whether the soft link is working correctly. It can be tested by reading and writing /container_data/test.txt in the Docker container and reading and writing /data/test.txt on the host.

First, run the following command inside the Docker container to redirect the contents of the test.txt file to /container_data/test.txt:

echo "test message in container" > /container_data/test.txt

Then, on the host machine, we can view the contents of the /data/test.txt file to verify whether the soft link works successfully:

cat /data/test.txt

You can see, ## The content in #test.txt is the same as what is set inside the Docker container.

Next, append some new content to the

/data/test.txt file on the host:

echo "test message in host" >> /data/test.txt

Then, we view it inside the Docker container again

/container_data/test.txt Contents of the file:

cat /container_data/test.txt

You can see that the newly added content has been correctly appended to the

test.txt file.

Summary

Through the above steps, we have successfully created a soft link inside the Docker container, linking a file in the container to a file on the host. document. In practical applications, soft links allow us to easily share files or directories, thereby improving the efficiency of development and management. Of course, when using soft links, we need to pay attention to the read and write permissions of the file or directory to ensure that the soft link can work properly.

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