Can a docker registry be copied from one machine to another?

Question

Can a docker registry populated on one host be 'tree-copied' to another machine and be 'turned on' as a pre-populated docker registry served by the new host?

I am working on a project providing Platform-as-a-Service which includes a docker registry service. These run in disconnected environments (not connected to the Internet). One very time consuming aspect of each deployment is creating an empty registry and loading, tagging, and pushing hundreds of docker images (tens of gigabytes of data) from a compressed tar into the registry for each new deployment.

I am thinking it would be faster to do this differently. Instead of a tarball of docker files, could we at 'build time' create and populate the docker registry then and compress that. At deploy time we just unpack the registry into /var/lib/registry or wherever...

But, I don't know if any of the data in the registry is dependent upon, say, a machine ID, certificate, or other aspect of the host upon which the registry was first running.

It seems to me an equivalent question is, if I populate two docker registries running on different machines with the same set of docker images in the same order, will the file contents of the registry folder be the same (or similar, allowing for timestamps and such?)

Every time I search for "docker registry transfer" or "move docker registry to new machine" or similar terms, I am flooded with answers about moving single docker images from one machine or registry to another, but don't see anything about docker registry migration or portability.

I haven't had the time or resources to test this out; maybe someone already expert in docker registry structures could clue me in that this is practical (or can say it absolutely will not work) I can make a better decision about whether to pursue getting the time and machines to demonstrate this approach.

Thank you.

question from:https://stackoverflow.com/questions/66049633/can-a-docker-registry-be-copied-from-one-machine-to-another

Answer 1

I don't know if any of the data in the registry is dependent upon, say, a machine ID, certificate, or other aspect of the host upon which the registry was first running.

• The configuration will be associated to the registry, for example, if you are running a secure registry by adding certs to the registry.

• In this case, you will have to configure the registry in the same manner on a new machine as on the previous machine, use a configuration manager(like ansible) for that.

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Instead of a tarball of docker files, could we at 'build time' create and populate the docker registry then and compress that. At deploy time we just unpack the registry into /var/lib/registry or wherever...

• Adding to what @DazWilkin already mentioned in the comments, a storage location can be configured which can be,
  • filesystem: the rootdirectory default is /var/lib/registry
  • based on the cloud provider if the registry is deployed on a private cloud
    • Example, S3 bucket for AWS
• You can take backup of that like the rootdirectory in case of filesystem or attach the storage location to the new registry.

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**Words of caution**

• Try to use the exact configuration and version of the docker registry.