[ER] Allow Elastic Package Registry to start without any installed packages

[fred-maussion]

Description

Currently, the Elastic Package Registry fails to start if no package is present in the configured directory. This behavior makes it difficult to deploy the registry in scenarios where packages are not yet available at installation time, a common case in lightweight installations or automated provisioning pipelines.

Use case

In environments where we build minimal Docker images or binaries for air-gapped or CI/CD-driven deployments, the registry should be allowed to start even if no packages are installed yet. This enables customers to bootstrap the infrastructure before loading packages through custom automation or manual uploads.

Expected behavior

The service should start successfully and return an empty package list (or an appropriate response), rather than fail or exit. Once packages are added, the registry should dynamically reflect the changes without requiring a restart.

Benefits

• Enables light installations and infrastructure-as-code deployments
• Improves developer experience and early-stage automation flows
• Reduces coupling between package availability and service lifecycle

Proposed solution

• Allow package-registry to start with zero packages present
• Log a warning such as: "No packages found at startup. The registry is running but no content is available yet."

A new flag would be added, that when used, would start the local indexer with a watcher for the configured directories, that would update the index when packages are added or removed.

[jsoriano]

Hey @fred-maussion, thanks for opening this feature request.

Just to be sure, the registry should be able to start without packages, and it must be able to dynamically discover them, without restart, after copying them, right?

The part of starting without packages would be easy, the part of discovering them after start can be more complex, and we would not enable it by default. I would add this as a new mode that can be enabled via some flag or environment variable.

[fred-maussion]

@jsoriano Yeah, that would be the expected scenario.
Based on your comment, my understanding is that there’s no subprocess that rescans the folder on a scheduled timer, is that correct? (Sorry if that’s a noob question.)

[jsoriano]

Based on your comment, my understanding is that there’s no subprocess that rescans the folder on a scheduled timer, is that correct? (Sorry if that’s a noob question.)

Correct, as package registry is implemented now, it only reads the packages on startup, so it needs to be restarted if packages are added later.

[fred-maussion]

It would be great to have an embedded process that rescans the configured folders at a configurable interval defined in the config.yml.
In the context of a locally deployed EPR integrated with a CI/CD pipeline, this would help avoid service disruptions especially for customers who may have alerts triggered when the service is unavailable.