Transferring data between a Docker host and a running container can be essential for various tasks, such as configuration changes, updates, or accessing sensitive information securely. In this tutorial, we will walk through the steps to copy an encrypted file from the Docker host to a running container.

Prerequisites:

• Access to the Docker host server.

• Docker installed and running on the host.

• Basic knowledge of working with Docker containers.

Task Overview:

The task involves copying an encrypted file (nautilus.txt.gpg) from the Docker host to a container named ubuntu_latest running on the same server. The file should be copied to the /home/ directory within the container.

1. SSH into the Host Server:

First, establish an SSH connection to the host server where the Docker container is running. Use appropriate credentials to access the server.

ssh user@host_server_ip

Replace user with your username and host_server_ip with the IP address of the server.

2. Copy the File to the Container:

Once logged in, execute the following command to copy the encrypted file from the Docker host to the container:

docker cp /tmp/nautilus.txt.gpg ubuntu_latest:/home/

• /tmp/nautilus.txt.gpg is the path to the encrypted file on the Docker host.

• ubuntu_latest is the name of the target container.

• /home/ is the destination directory within the container.

3. Verify the Copy Operation:

To ensure that the file has been successfully copied to the container, you can verify its presence using the docker container exec command. Execute the following command:

docker container exec -it ubuntu_latest ls /home/

This command lists the contents of the /home/ directory within the ubuntu_latest container. If the copy operation was successful, you should see the nautilus.txt.gpg file listed among the files in the directory.

Conclusion:

In this tutorial, you learned how to securely copy a file from the Docker host to a container running on the same server. This process ensures the confidentiality of data while allowing seamless data transfer between the host and containers. This skill is valuable for managing and maintaining secure data workflows within Docker environments.