fix: probe timeouts, pm2 log storage, writer concurrency, redis QoS; bump to 2026-07-26-004

[twk3]

Bumps the chart to 0.7.5 and the image to 2026-07-26-004, and fixes four defaults that made a busy install restart itself.

All four were found while debugging a self-hosted customer whose pods entered CrashLoopBackOff under CI load. The application-side root cause of their incident is currents-dev/currents#3646 / ENG-1382 — the fix that ships in 2026-07-26-004. Everything here is separate: chart defaults that made the symptom worse and would bite any install under load.

1. Every probe ran at a 1 second timeout

No probe in the chart set timeoutSeconds, so all of them ran at the Kubernetes default of 1 second, with no startupProbe anywhere.

• A service that is merely busy answers more slowly than one second under load, so the default turns a slow pod into a restarting one.
• Worse for writer, scheduler and webhooks, whose probes exec a pm2 show — that forks a full Node CLI, which cannot finish inside a second while the container is under CPU pressure. Timed-out probe processes then accumulate and make the pressure worse, which is why raising failureThreshold alone did not help the customer.
• With no startupProbe, the liveness initialDelaySeconds was the only thing covering a slow start, so a slow start became a restart loop.

Every probe now has an explicit timeoutSeconds, periodSeconds and failureThreshold, and each service gets a startupProbe so liveness and readiness are held off until the container is actually up. HTTP probes get a 10s liveness timeout; the pm2 show probes get 15s and a 30s period.

2. pm2's home directory was in RAM

PM2_HOME (/home/node/.pm2) was an emptyDir with medium: "Memory" and no sizeLimit, on server, writer, scheduler and webhooks.

pm2 only writes log files there for services started from an ecosystem file — on the CLI path it sends them to /dev/null. In this chart that is the writer, so the writer's logs were charged to the pod's memory limit with no rotation and no bound. Under an error storm that is an OOMKill; on ECS the identical writes go to the task's disk and are invisible.

It is now disk-backed with a configurable sizeLimit (<service>.pm2HomeSizeLimit), defaulting to 256Mi — pm2's sockets and logs should never approach that, so if a pod does hit it the eviction is the signal you want rather than a silent OOM.

I also briefly moved the toolbox's /tmp off tmpfs and then reverted it: /tmp there holds only the named pipes the import creates (mkfifo('/tmp/merge-<collection>.bson'), removed in a finally). The transformed BSON flows through the kernel pipe between transform-mongo and mongorestore and never touches the filesystem, and the export itself lands on the PVC via fetch-artifact --out=/data/export. Nothing spills there, so the tmpfs is fine as it is.

3. Writer ran one Node process per pod

PM2_INSTANCES was never set, so pm2 defaulted to 1. Each writer pod ran a single Node process and could not use a second core no matter how the pod was sized — the only way to scale was replicas, at 2× the pods and memory requests the hosted service needs for the same throughput.

Added writer.pm2Instances, defaulting to 2, which is what the hosted service runs (writerStack sets PM2_INSTANCES: '2' at 2 vCPU).

4. The bundled Redis was BestEffort

redis.master.resourcesPreset: "none" rendered an empty resources block, so the Redis pod had no requests or limits at all — BestEffort QoS, the first thing the kubelet evicts under node memory pressure. Evicting it drops every service's queue connection at once, which reads as several unrelated pods crashlooping together.

It now gets requests (500m / 1Gi) but deliberately no limit, so it stops being the first eviction target without turning a queue backlog into an OOMKill. The comment tells operators to size it to their queue depth.

Compatibility

Probe values are maps, so Helm deep-merges them — an install that overrides only timeoutSeconds keeps the chart's httpGet / exec handler and picks up the new defaults for anything it did not set. Verified against a partial override:

server:
  livenessProbe:
    initialDelaySeconds: 180
    timeoutSeconds: 15

renders as

livenessProbe:
  failureThreshold: 6        # from the chart
  httpGet: {path: /, port: http}
  initialDelaySeconds: 180   # from values
  periodSeconds: 20          # from the chart
  timeoutSeconds: 15         # from values

The only behaviour change for an install that overrides nothing is the intended one: longer probe timeouts, a startup probe, pm2's home on disk, two writer processes per pod, and Redis holding a resource request.

Moving PM2_HOME off tmpfs shifts that usage from pod memory to node ephemeral storage, capped at 256Mi per pod.

Validation

• helm lint clean.
• helm template rendered against a representative production values file and against a partial-probe-override file; probe blocks, PM2_INSTANCES, sizeLimits and Redis requests all render as intended.
• grep -rn medium charts/currents/templates/ returns only the toolbox FIFO mount, which is intentional.
• ./scripts/build-docs.sh run; docs/configuration.md regenerated so the docs-check workflow passes.

Also in here

values.yaml had # Server Configuration where it meant # END Server Configuration. Corrected, since it makes the section markers parseable.

Not in here

The OTel metric reader is unconditionally enabled in the application and exports to OTEL_EXPORTER_OTLP_ENDPOINT, defaulting to localhost:4317. Traces, logs and auto-instrumentation are all gated behind OTEL_TRACES_ENABLED / OTEL_LOGS_ENABLED, but getMetricReader() is not, so every service on every on-prem install attempts a gRPC export every 30 seconds that can never succeed. That needs an application fix, not a chart one.

Summary by CodeRabbit

• New Features
  • Added configurable startup, liveness, and readiness probes for Currents services.
  • Added configurable PM2 storage limits and PM2 worker instance settings.
  • Added Redis resource requests for improved deployment configuration.
• Improvements
  • Updated the Currents image and chart versions.
  • Replaced in-memory PM2 storage configuration with configurable size limits.
• Documentation
  • Updated configuration documentation with the new probe, storage, worker, and Redis settings.

[coderabbitai]

📝 Walkthrough

Walkthrough

The Helm chart adds configurable startup probes, PM2 storage limits, writer PM2 instances, Redis resource requests, updated release metadata, and matching configuration documentation across Currents services.

Changes

Currents chart configuration

Layer / File(s)	Summary
Configuration defaults and reference charts/currents/Chart.yaml, charts/currents/values.yaml, docs/configuration.md	The chart updates release metadata and the image tag. Values and documentation add startup probes, probe thresholds and timings, PM2 settings, storage limits, Redis requests, and a corrected configuration terminator.
Deployment probe and volume wiring charts/currents/templates/*/deployment.yaml	Deployment templates render optional startup probes, apply configurable PM2 volume size limits, and set PM2_INSTANCES for the writer deployment.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: 🟡 Moderate · up to 293e9

The chart is not ready to publish because it declares version 0.7.5 rather than 0.8.0. Consumers requesting the intended release would be unable to install it until the chart version and generated documentation are corrected.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main changes: probe settings, PM2 storage, writer concurrency, Redis resources, and the image version update.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/probe-defaults-and-pm2-log-storage

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[coderabbitai]

Actionable comments posted: 1

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Inline comments:
In `@charts/currents/Chart.yaml`:
- Line 8: Update the chart version in Chart.yaml from 0.7.5 to 0.8.0, then
regenerate docs/configuration.md to reflect the new chart release.

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• charts/currents/Chart.yaml
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• docs/configuration.md

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