[ENH] Configure the cache to have a hostPath and mountPath for log service.

[rescrv]

Description of changes

This adds defaults to values.yaml that make k8s instantiate the log with a cache dir mounted.

Test plan

CI + eyes.

Documentation Changes

N/A

[github-actions]

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[propel-code-bot]

This PR adds cache configuration for the Rust log service in the Kubernetes deployment by introducing hostPath and mountPath parameters in values.yaml. It also bumps the Helm chart version accordingly from 0.1.38 to 0.1.39.

This summary was automatically generated by @propel-code-bot

[github-actions]

✅ The Helm chart's version was changed. Your changes to the chart will be published upon merge to main.

[propel-code-bot]

[DataTypeCheck]

The env: key on line 54 implies an empty map ({}). However, other services in this file (e.g., sysdb, logService) define env as a list of name/value pairs. If Helm templates expect a list (e.g., for iteration with range), this type mismatch can cause errors or unexpected behavior. For an empty list of environment variables, it should be env: [] to maintain consistency and ensure correct template processing.

Suggested change

	env:
	env: []

⚡ Committable suggestion

Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation.

[jasonvigil]

I agree with this suggestion. Though, why do we need the env field here?

[rescrv]

Yaml cargo culting on my part. I'll remove.

[propel-code-bot]

[ArchitectureDecision]

Using hostPath for the cache volume (line 56) ties the cache data to a specific node. In a multi-node Kubernetes cluster, if the pod is rescheduled to a different node, the cache data will be lost or become inconsistent. For production deployments or multi-node environments requiring persistent cache, consider using PersistentVolumeClaim (PVC) for more robust and portable cache storage. hostPath is generally more suitable for single-node clusters or local development setups where node affinity is guaranteed and simplicity is prioritized.

[jasonvigil]

I also agree with this suggestion, but understand that we have made this trade-off for performance reasons.

[HammadB]

If you think we can have cache coherency across deploys another way we can make that change. it’s possible to not use hostpath but still mount the local disk. We should probably do that, i think it was just some clunkiness on our deployed env that made it hard

Alternatively if you have a system design that doesn’t need cache coherency would love to hear about it.