Let’s see the steps to change a VMDK image to a Docker container. Bobcares, as a part of our Docker Hosting Support Services, offers solutions to every query that comes our way.

How to convert VMDK to Docker?

We have to follow the below steps to convert VMDK to Docker:

• Firstly, launch the Ubuntu software and enter root mode using the below command:

  su root
• Now update Ubuntu with the command:

  apt-get update && apt-get upgrade
• Now install qemu-img in order to convert the existing VM VDMK file to a RAW file for Docker use. Use the below command. Accept all prompts.

  apt-get install qemu-utils
• Ubuntu will automatically map access to the Windows C partition. If VMs are in separate folders in the Windows partition, then use the folder, and execute the below code. We have to use the directory name on the system where we have the VMs stored.

  cd /mnt/c/directory_name\VM
• In order to use the existing VMDK, we must change it into a raw file. Create a directory called container under the specific VM folder of the image we’re converting before starting the conversion process. This folder will house the output from the conversion work.
• Then convert the VMDK to a raw file using the below command:

  qemu-img convert -O raw <source VMDK file> <destination>
• After it completes, look at the partition table on the new RAW file to obtain the information necessary to mount the file for additional use.
• Then choose the value in the “Start” column on the boot sector output.
• In order to mount the partition for use, create a mount using the following command:

  mkdir /mnt/container
• Also, mount the RAW file using the command:

  mount -o loop,ro,offset=1045876 container/image.raw /mnt/container
• Now verify whether the mount is successful or not using the command:

  ls /mnt/container
• We can now view the VM’s file system. So to put the entire partition in a tarball, use the following code:

  tar -C /mnt/container -czf image.tar.gz container/
• As soon as the tarball is ready, we have to import it to Docker. As soon as we are certain that Docker is up and running on the computer, start a PowerShell session in Administrator mode and go to the container folder where the tarball is located. Now to import the tarball into Docker, use the below command:

  docker import <filename> <repository>:<tag>
• Type the code below when the import procedure is finished. This will provide details about the new Docker image needed to run a new container.

  docker images
• From the docker image, start a new container:

  docker run -i -t <image id> <commands>
• Finally, as the container is working, we can move around the environment as necessary.

We can also end a container using the command docker stop <container_name>. Confirmation that the container has stopped functioning can be seen in the output of the container name after performing the command.

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Conclusion

In this article, we included simple steps from our Support team to convert a VMDK image to a Docker container.