Making the Docker Registry HA

Question

Please note: This is a very similar question as this one, but I assert this is not a dupe! That other question was clearly based on the (older) Python-based Docker registry, not the latest one that is written in GoLang and seems to be fairly different!

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I just spent a few hours reading the docs for setting up a private Docker Registry and have it running on a remote VM with the following characteristics:

• Authenticated using Basic Auth, and I have a test user working with it
• Uses a root CA cert for TLS
• Uses the local file system for storage (I'll probably upgrade this to Ceph/Rados)

So far so good. But now I want to make it HA, and am shocked that the docs don't seem to make any mention of it. In the old Python docs there is a whole section devoted to HA, but I'm leery of following them because the newer (GoLang-based) registry doesn't seem to mention HA at all.

So my concerns:

• Is there a way to make the newer (GoLang) registry HA? If so, where are the docs?
• What's the general approach? Cluster registry instances behind a load balancer? Make one the Primary and have 1+ Secondaries? Master/slave?

Answer 1

This is actually referenced in "Deploying a registry server - Load Balancing Considerations"

One may want to use a load balancer to distribute load, terminate TLS or provide high availability. While a full load balancing setup is outside the scope of this document, there are a few considerations that can make the process smoother.

The most important aspect is that a load balanced cluster of registries must share the same resources. For the current version of the registry, this means the following must be the same:

• Storage Driver
• HTTP Secret
• Redis Cache (if configured)

That means the actual high-availability feature is considered out-of-scope for the docker distribution project, but it can still be implemented by adding a load balancer.