Menu
I'm wondering where Docker's images are exactly stored to in my local host machine. Can I share my Docker-Image without using the Docker-Hub or a Dockerfile but the 'real' Docker-Image? And what is exactly happening when I 'push' my Docker-Image to Docker-Hub?
697
To share Docker images, you have to use a Docker registry. The default registry is Docker Hub and is where all of the images we've used have come from. A Docker ID allows you to access Docker Hub which is the world's largest library and community for container images. Create a Docker ID for free if you don't have one.
This means that if your company has 250+ employees or more than $10 million in annual revenue you will not able to use Docker Desktop without a paid subscription. It remains free for smaller companies, private use, open-source projects, and educational purposes.
In an ideal scenario, transferring docker images is done through the Docker Registry or though a fully-managed provider such as AWS's ECR or Google's GCR. You can easily upload an image through the docker push command, and others can pull the image using the docker pull command.
Docker images are stored as filesystem layers. Every command in the Dockerfile creates a layer. You can also create layers by using docker commit from the command line after making some changes (via docker run probably).
These layers are stored by default under /var/lib/docker. While you could (theoretically) cherry pick files from there and install it in a different docker server, is probably a bad idea to play with the internal representation used by Docker.
When you push your image, these layers are sent to the registry (the docker hub registry, by default… unless you tag your image with another registry prefix) and stored there. When pulling, the layer id is used to check if you already have the layer locally or it needs to be downloaded. You can use docker history to peek at which layers (other images) are used (and, to some extent, which command created the layer).
As for options to share an image without pushing to the docker hub registry, your best options are:
docker save an image or docker export a container. This will output a tar file to standard output, so you will like to do something like docker save 'dockerizeit/agent' > dk.agent.latest.tar. Then you can use docker load or docker import in a different host.
Host your own private registry. - Outdated, see comments See the docker registry image. We have built an s3 backed registry which you can start and stop as needed (all state is kept on the s3 bucket of your choice) which is trivial to setup. This is also an interesting way of watching what happens when pushing to a registry
Use another registry like quay.io (I haven't personally tried it), although whatever concerns you have with the docker hub will probably apply here too.
187
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
