Goals

• Improve reliability of existing LokiStack installations seamlessly by applying a set of default Affinity/Anti-Affinity polices for 
• Enable users to tune Affinity/Anti-Affinity per component in the LokiStack custom resource

Non-Goals

• Auto-remidiation of Affinity/Anti-Affinity policies by the Loki Operator in case of unscheduled pods.

Motivation

In Cloud Native environments it's common practice to define Affinity or AntiAffinity rules for application to improve resilience or performance.

LokiStack should thus have some default AntiAffinity rules applied to improve overall resilience of the service and prevent running the complete stack on one or just two OpenShift Container Platform 4 - Node that could create a problematic scenario in case of such a OpenShift Container Platform 4 - Node failure.

Alternatives

Acceptance Criteria

• The node placement of existing installations is improved, so that, ideally, no critical components are sharing the same node.
• Users can tune the Affinity/Anti-Affinity setup by considering the cluster topology.

Risk and Assumptions

Documentation Considerations

• Requires to document the default Affinity/Anti-Affinity policies we apply per Loki component.
• Requires to document how to tune (e.g. apply overrides) of the default Affinity/Anti-Affinity policies via the LokiStack custom resource.

Open Questions

Additional Notes