Currently Zarf uses a helm chart to deploy a docker registry. This chart utilizes deployments with an optional PVC for persistence. We need to define a better solution for making the registry highly-available and fault-tolerant. This issue exists to facilitate that discussion.

Concerns:

• Storage classes are cluster/distro-specific and a default storage class does not always exist
• Using a simple deployment with multiple replicas requires a RWX access mode to tolerate Node failure/taints
• Docker registry does support S3/Minio object storage, but that introduces a new complex dependency (Minio) or a vendor cloud dependency (AWS)
• Pushing to a svc vs every running pod without RWX or S3-backed storage will create an inconsistent state of image availability. In other words one pod would have the pushed image, the others would not

Considerations:

• Docker registry as an OCI Distribution Spec API makes it trivial to synchronize registries with tools we already have in Zarf such as Crane.
• For HA we don't need a daemonset such as Kube-Fledged as 3+ registries distributed across nodes (if 3 nodes are available) would still provide HA
• We have solved the initial lack of a registry issue with Distro-Agnostic Zarf Registry Bootstrap #329, so we can assume a seed registry will already exist in the cluster during bootstrapping