Goals

1. Expose Loki's stream-based retention capabilities in the LokiStack custom resources for OpenShift Administrators.
2. Expose Loki's stream-based retention capabilities in the LokiStack custom resource for OpenShift Application owners.

Motivation

The Loki Operator manages LokiStack resources that consists of a set of Loki components for ingestion/querying and optionally a gateway microservice that ensures authenticated and authorized access to logs stored by Loki. Retention in Loki has always been global for a cluster and deferred to the underlying object store. Since v2.3.0 Loki can handle retention through the Compactor component. Retention can be configured per tenant and per stream. These different retention configurations allow storage cost control and meet security and compliance requirements in a more granular way. A common use case for custom policies is to delete high-frequency logs earlier than other (low-frequency) logs.

Acceptance Criteria

1. The OpenShift Administrator can enable the retention via the LokiStack custom resource.
2. The OpenShift Administrator can declare per-tenant and global policies through the LokiStack custom resource ordered by priority.

Risk and Assumptions

1. Assuming the OpenShift Administrators are the single eliglibable persona to configure stream-based retention polices for all application owners
2. OpenShift Application owners can only delegate their retention policy requests w/o having access rights to edit the Lokistack custom resource.

Documentation Considerations

[rkratky] Provide procedure docs for enabling/configuring the retention policies.

Additional Notes

1. Enhancement Proposal (Upstream): Loki Operator Stream-based Retention