Create a Docker Image from a Running Linux System

Step 1: Archive the Root Filesystem

Run the following command to create an archive of your root filesystem while excluding special directories:

sudo tar -P --exclude=/proc --exclude=/sys --exclude=/dev --exclude=/tmp --exclude=/run --exclude=/mnt --exclude=/media -czf host_fs.tar.gz /

Command Breakdown & Analysis

tar: The command-line utility for creating, extracting, and managing archive files.
-P: The option will create archives with absolute paths.
--exclude=/proc --exclude=/sys --exclude=/dev --exclude=/tmp --exclude=/run --exclude=/mnt -exclude=/media
-czf host_fs.tar.gz /: Creates a compressed tar archive named host_fs.tar.gz from the root filesystem.



            Directory Exclusions Explained
            
                
                    
                        Directory
                        Reason for Exclusion
                    
                
                
                    /proc Virtual filesystem containing kernel and process information (non-persistent data).
                    /sys Kernel-related system information (dynamically generated).
                    /dev Device nodes, not normal files.
                    /tmp Temporary files that do not need to be backed up.
                    /run Runtime process data (e.g., PID files, sockets).
                    /mnt Mounted filesystems (could be external devices).
                    /media Mounted media like USBs and CDs.
                
            
            
            Step 2: Create the Dockerfile
            Create a file named Dockerfile with the following content:
            FROM scratch
ADD host_fs.tar.gz /
CMD ["/bin/bash"]
            
            Step 3: Build the Docker Image
            Run the following command to build the Docker image:
            docker build -t host_based_image .
            
            Step 4: Run a Container Based on This Image
            Use this command to start a container using the newly created image:
            docker run --rm -it host_based_image
            
            Additional Considerations
            
                The scratch base image is empty, meaning your image will be an exact copy of your system.
                Some Linux distributions require additional dependencies.
                If your Linux system uses systemd or other init systems, you may need special setup steps.

Directory	Reason for Exclusion
/proc	Virtual filesystem containing kernel and process information (non-persistent data).
/sys	Kernel-related system information (dynamically generated).
/dev	Device nodes, not normal files.
/tmp	Temporary files that do not need to be backed up.
/run	Runtime process data (e.g., PID files, sockets).
/mnt	Mounted filesystems (could be external devices).
/media	Mounted media like USBs and CDs.