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feat(supervisor): add cluster pod-count dequeue backpressure source#4027

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feat/supervisor-podcount-backpressure
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feat(supervisor): add cluster pod-count dequeue backpressure source#4027
nicktrn wants to merge 11 commits into
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feat/supervisor-podcount-backpressure

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@nicktrn

@nicktrn nicktrn commented Jun 24, 2026

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Adds an in-process backpressure signal that pauses dequeuing when the Kubernetes cluster is saturated, so work overflows cheaply in the queue instead of piling up as unschedulable pods. Saturation is read by scraping the apiserver's total pod-object count (apiserver_storage_objects{resource="pods"}) and applying an engage/release threshold with hysteresis - a single lightweight aggregate scrape, not a pod listing.

Backpressure sources are now evaluated independently and OR'd: each source has its own enable and dry-run flag, and the supervisor engages if any enabled source trips. This adds the pod-count source alongside the existing one without changing it, and is extensible to more sources later. Off by default.

The scrape uses the in-cluster kubeconfig over https so TLS verifies against the cluster CA (the fetch-options helper attaches the CA as an https.Agent, which the global fetch ignores - that path silently dropped the CA). Enabling the pod-count source requires the supervisor's service account to be granted get on the /metrics non-resource URL; that RBAC and the per-deployment env wiring are operator-side and live elsewhere.

New config (pod-count source): TRIGGER_DEQUEUE_BACKPRESSURE_POD_COUNT_ENABLED (default false), _POD_COUNT_DRY_RUN (default true), _POD_COUNT_ENGAGE / _POD_COUNT_RELEASE (hysteresis thresholds), _POD_COUNT_REFRESH_MS (scrape interval, default 5s). The existing source's flags are unchanged.

Observability: a supervisor_cluster_pod_count gauge, and the pod-count monitor's metrics are namespaced (supervisor_backpressure_pod_count_*) so the existing backpressure metrics keep their names.

@nicktrn nicktrn self-assigned this Jun 24, 2026
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⚠️ No Changeset found

Latest commit: 33929da

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Review Change Stack

Walkthrough

The supervisor gains an opt-in Kubernetes pod-count backpressure source. A new parsePodCount function extracts the apiserver_storage_objects{resource="pods"} value from raw Prometheus text, and K8sPodCountSignalSource wraps it with hysteresis-based engage/release logic. A new createApiserverMetricsFetcher function performs authenticated HTTPS GET requests to the Kubernetes apiserver /metrics endpoint. The Env schema is exported and extended with pod-count configuration fields. In index.ts, the single optional backpressureMonitor is replaced with a backpressureMonitors array; both Redis and pod-count monitors can be active simultaneously, with session gating using some(...) across all monitors. Lifecycle start/stop iterates the full array.

🚥 Pre-merge checks | ✅ 3 | ❌ 2

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Docstring Coverage ⚠️ Warning Docstring coverage is 25.00% which is insufficient. The required threshold is 80.00%. Write docstrings for the functions missing them to satisfy the coverage threshold.
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Check name Status Explanation
Title check ✅ Passed The title is concise and accurately summarizes the new pod-count backpressure source.
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✅ Devin Review: No Issues Found

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Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)
apps/supervisor/src/clients/kubernetes.ts (1)

86-99: 🩺 Stability & Availability | 🟠 Major

Handle truncated response bodies so the scrape promise always settles.

req.on("error") covers connect failures, but if the apiserver closes the response before end, this promise can still hang. Reject on res.on("close") when res.readableEnded is false (or use stream.finished) instead of relying on aborted.


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  • apps/supervisor/src/clients/kubernetes.ts
  • apps/supervisor/src/env.test.ts
  • apps/supervisor/src/env.ts
  • apps/supervisor/src/index.ts
🚧 Files skipped from review as they are similar to previous changes (3)
  • apps/supervisor/src/env.test.ts
  • apps/supervisor/src/env.ts
  • apps/supervisor/src/index.ts
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**/*.{ts,tsx}

📄 CodeRabbit inference engine (.github/copilot-instructions.md)

**/*.{ts,tsx}: Use types over interfaces for TypeScript
Avoid using enums; prefer string unions or const objects instead

Import from @trigger.dev/sdk when writing Trigger.dev tasks. Never use @trigger.dev/sdk/v3 or deprecated client.defineJob

Files:

  • apps/supervisor/src/clients/kubernetes.ts
**/*.{ts,tsx,js,jsx}

📄 CodeRabbit inference engine (.github/copilot-instructions.md)

Use function declarations instead of default exports

**/*.{ts,tsx,js,jsx}: Prefer static imports over dynamic imports. Only use dynamic import() when circular dependencies cannot be resolved, code splitting is needed for performance, or the module must be loaded conditionally at runtime
Import subpaths only from packages/core (@trigger.dev/core), never import from the root

Files:

  • apps/supervisor/src/clients/kubernetes.ts
**/*.ts

📄 CodeRabbit inference engine (.cursor/rules/otel-metrics.mdc)

**/*.ts: When creating or editing OTEL metrics (counters, histograms, gauges), ensure metric attributes have low cardinality by using only enums, booleans, bounded error codes, or bounded shard IDs
Do not use high-cardinality attributes in OTEL metrics such as UUIDs/IDs (envId, userId, runId, projectId, organizationId), unbounded integers (itemCount, batchSize, retryCount), timestamps (createdAt, startTime), or free-form strings (errorMessage, taskName, queueName)
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  • apps/supervisor/src/clients/kubernetes.ts
apps/supervisor/src/clients/**/*.{js,ts}

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Platform communication (webapp/coordinator) clients should be organized in src/clients/

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  • apps/supervisor/src/clients/kubernetes.ts
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Files:

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🧠 Learnings (9)
📚 Learning: 2026-03-22T13:26:12.060Z
Learnt from: ericallam
Repo: triggerdotdev/trigger.dev PR: 3244
File: apps/webapp/app/components/code/TextEditor.tsx:81-86
Timestamp: 2026-03-22T13:26:12.060Z
Learning: In the triggerdotdev/trigger.dev codebase, do not flag `navigator.clipboard.writeText(...)` calls for `missing-await`/`unhandled-promise` issues. These clipboard writes are intentionally invoked without `await` and without `catch` handlers across the project; keep that behavior consistent when reviewing TypeScript/TSX files (e.g., usages like in `apps/webapp/app/components/code/TextEditor.tsx`).

Applied to files:

  • apps/supervisor/src/clients/kubernetes.ts
📚 Learning: 2026-03-22T19:24:14.403Z
Learnt from: matt-aitken
Repo: triggerdotdev/trigger.dev PR: 3187
File: apps/webapp/app/v3/services/alerts/deliverErrorGroupAlert.server.ts:200-204
Timestamp: 2026-03-22T19:24:14.403Z
Learning: In the triggerdotdev/trigger.dev codebase, webhook URLs are not expected to contain embedded credentials/secrets (e.g., fields like `ProjectAlertWebhookProperties` should only hold credential-free webhook endpoints). During code review, if you see logging or inclusion of raw webhook URLs in error messages, do not automatically treat it as a credential-leak/secrets-in-logs issue by default—first verify the URL does not contain embedded credentials (for example, no username/password in the URL, no obvious secret/token query params or fragments). If the URL is credential-free per this project’s conventions, allow the logging.

Applied to files:

  • apps/supervisor/src/clients/kubernetes.ts
📚 Learning: 2026-05-18T08:21:27.694Z
Learnt from: d-cs
Repo: triggerdotdev/trigger.dev PR: 3632
File: apps/webapp/sentry.server.ts:4-21
Timestamp: 2026-05-18T08:21:27.694Z
Learning: When handling Prisma error P1001 ("Can't reach database server") in TypeScript, don’t assume a single error shape. Prisma can surface P1001 via two different error classes/fields: `PrismaClientKnownRequestError` exposes it as `err.code === "P1001"` (common during mid-query connection drops), while `PrismaClientInitializationError` exposes it as `err.errorCode === "P1001"` (common on client startup failure). Therefore, predicates should use `err.code === "P1001" || err.errorCode === "P1001"`. Do not flag `err.code === "P1001"` as “unreachable/never matches,” as it is expected in production.

Applied to files:

  • apps/supervisor/src/clients/kubernetes.ts
📚 Learning: 2026-05-18T08:21:27.694Z
Learnt from: d-cs
Repo: triggerdotdev/trigger.dev PR: 3632
File: apps/webapp/sentry.server.ts:4-21
Timestamp: 2026-05-18T08:21:27.694Z
Learning: When handling Prisma errors for P1001 ("Can't reach database server"), do not assume it only appears under a single property name. Prisma may surface P1001 via either `PrismaClientKnownRequestError` (`err.code === "P1001"`, e.g., mid-query connection drops) or `PrismaClientInitializationError` (`err.errorCode === "P1001"`, e.g., client startup connection failure). To reliably detect the condition, check `err.code === "P1001" || err.errorCode === "P1001"`, and avoid review rules that would incorrectly flag `err.code === "P1001"` as unreachable/never-matching.

Applied to files:

  • apps/supervisor/src/clients/kubernetes.ts
📚 Learning: 2026-06-13T19:53:13.759Z
Learnt from: ericallam
Repo: triggerdotdev/trigger.dev PR: 3937
File: packages/trigger-sdk/skills/realtime-and-frontend/SKILL.md:258-260
Timestamp: 2026-06-13T19:53:13.759Z
Learning: When reviewing code that uses `trigger.dev/react-hooks`’s `useRealtimeRun`, preserve the call signature where the first argument is the full realtime handle object (not `handle.id`). This is intentional to maintain type-safety and is consistent with the official docs; do not suggest changing the first argument from the handle object to `handle.id`.

Applied to files:

  • apps/supervisor/src/clients/kubernetes.ts
📚 Learning: 2026-06-17T17:13:49.929Z
Learnt from: matt-aitken
Repo: triggerdotdev/trigger.dev PR: 3948
File: apps/webapp/app/routes/_app.orgs.$organizationSlug.projects.$projectParam.env.$envParam.bulk-actions.$bulkActionParam/route.tsx:48-62
Timestamp: 2026-06-17T17:13:49.929Z
Learning: In triggerdotdev/trigger.dev, within `dashboardLoader`/`dashboardAction` (or similar context resolver code) whenever you resolve an organization ID from an organization slug for RBAC/enterprise authorization scope, always read from the primary Prisma client (`prisma`), not `$replica`. Using `$replica` can hit replica-lag and cause the RBAC lookup/authorization to run without the correct org scope (bypassing intended role enforcement). Implement the slug→org lookup with `prisma.organization.findFirst(...)` (or equivalent primary-client query) and add an inline comment documenting why the primary client is required (replica lag could lead to unscoped RBAC checks).

Applied to files:

  • apps/supervisor/src/clients/kubernetes.ts
📚 Learning: 2026-06-23T13:04:21.413Z
Learnt from: carderne
Repo: triggerdotdev/trigger.dev PR: 4023
File: apps/webapp/app/services/upsertBranch.server.ts:14-18
Timestamp: 2026-06-23T13:04:21.413Z
Learning: In TypeScript, it’s valid to `import { type X }` and then use `typeof X` in a type-only position, e.g. `type Alias = z.infer<typeof X>`. The `type` modifier suppresses the runtime import, but the type checker still has the full exported type so `z.infer<typeof X>` can resolve correctly. In code reviews, don’t flag this as a TypeScript compile error as long as `typeof X` is used in a type context (e.g., with `z.infer`, `type` aliases, generics), not as a runtime value.

Applied to files:

  • apps/supervisor/src/clients/kubernetes.ts
📚 Learning: 2026-06-04T18:16:35.386Z
Learnt from: nicktrn
Repo: triggerdotdev/trigger.dev PR: 3836
File: apps/supervisor/src/backpressure/backpressureMonitor.ts:3-5
Timestamp: 2026-06-04T18:16:35.386Z
Learning: When reviewing TypeScript in this repo, apply the rule “prefer type aliases over interfaces” only to data/object shapes and union/intersection type modeling. If an interface is being used as a behavioral contract for collaborators to implement (e.g., method-shape interfaces that define required behavior, such as `BackpressureLogger` / `BackpressureSignalSource` in `apps/supervisor/src/backpressure/backpressureMonitor.ts`), keep it as an `interface` and do not flag it as a type-alias-vs-interface violation.

Applied to files:

  • apps/supervisor/src/clients/kubernetes.ts
📚 Learning: 2026-06-09T17:58:04.699Z
Learnt from: 0ski
Repo: triggerdotdev/trigger.dev PR: 3879
File: apps/webapp/app/models/vercelIntegration.server.ts:619-630
Timestamp: 2026-06-09T17:58:04.699Z
Learning: In this codebase, outbound raw `fetch` calls should typically rely on Node/undici’s default request timeout (about ~300s) rather than adding a per-call `AbortController` + `setTimeout` wrapper inside individual functions (e.g. in files like `apps/webapp/app/models/vercelIntegration.server.ts`). During code review, do not flag the absence of a per-call timeout on a single `fetch` as an issue; if per-call timeouts are needed, they should be implemented via a codebase-wide convention (e.g., a shared fetch wrapper or documented pattern) rather than ad-hoc per-function changes.

Applied to files:

  • apps/supervisor/src/clients/kubernetes.ts
🔇 Additional comments (1)
apps/supervisor/src/clients/kubernetes.ts (1)

63-84: LGTM!

Also applies to: 101-105

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