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Pulling content directly from the Docker Daemon…

By Dan Walsh GitHub Twitter

Cool things you can do with Podman.

I recently received a bug report about some huge container images not working correctly in Docker. So I suggested to the reporter that they try them with Podman. He responded that he saw the images with docker images, but did not see them with podman images.

I explained to him that the Docker image and container database are separate from the Podman image and container database. I told him he would have to pull the images into Podman. Then I decided to try a cool feature of Podman, where I could pull images directly out of the Docker daemon.

First I look for the Centos Image inside of Docker.

# docker images | grep centos                  	7               	49f7960eb7e4    	2 months ago    	200 MB

Podman has the ability through its use of containers/image to pull images using many different transports other than just pulling from Container Registries. It supports pulling directly from the Docker daemon, using the docker-daemon transport.

# podman pull
Getting image source signatures
Copying blob sha256:bcc97fbfc9e1a709f0eb78c1da59caeb65f43dc32cd5deeb12b8c1784e5b8237
 198.59 MB / 198.59 MB [====================================================] 1s
Copying config sha256:49f7960eb7e4cb46f1a02c1f8174c6fac07ebf1eb6d8deffbcb5c695f1c9edd5
 2.15 KB / 2.15 KB [========================================================] 0s
Writing manifest to image destination
Storing signatures

Now you have the Centos 7 image in Podman containers/storage datastore.

#podman images | grep centos        	7    	49f7960eb7e4   2 months ago   .com208MB

Now you can start using the image with Podman, Buildah and CRI-O. You can even create new images and push them back into the Docker daemon.

Try it out…