> Per AI Blitz Plan §claude. Layer: 1. Repo: devops-infra-helm-charts.

# 02 — Cluster fleet

The repo's cluster directories under `helm-overrides/<cluster>/` are the canonical list of clusters this platform serves. Naming follows three patterns; each implies a different scheduling primitive set, which is why **schedule fields are never copy-pasted between clusters** (see [`../docs/global/SANCTITY_RULES.md`](../docs/global/SANCTITY_RULES.md)).

## Naming taxonomy

### `k8s-<bu>-prd-ase1[c]`

Standard GKE prod cluster, BU-owned. All in `asia-southeast1`, fleet `meesho-admin-prd-0622`. Trailing `c` denotes a secondary cluster for the same BU.

Known BUs in this repo:

- `central`, `central-mqkafka`
- `supply`, `supply-dev`
- `demand`
- `dataengg`, `datascience`, `dengspark`, `dengspark-di`, `dengspark-notebook`, `dscispark`
- `dsgpu`
- `farmiso`
- `ml-platform`
- `admin`, `sec-admin`, `devops-admin`

A few of these are GKE **Autopilot** clusters (different scheduling primitives — see below):
- `k8s-central-prd-ase1`
- `k8s-dsgpu-prd-ase1`
- `k8s-shared-int-ase1`

The rest are **standard** GKE.

### `k8s-shared-int-ase1`

Shared **integration** (pre-prod) cluster — the only non-prod cluster in the repo. Used for integration testing of platform changes before they hit any prod cluster. Autopilot.

### `k8s-aurva-prd-ase1`

Aurva integration (third-party security tooling). Minimal override set.

### `db-<numeric-id>-...`

Auto-named dataplane / data-tier clusters. Each carries a minimal override set, typically `kube-state-metrics` and `victoria-metrics-agent` only. The `fullnameOverride` convention here is `<kind>-dbc-<bu>-prd` so that metrics labels stay legible across the data-tier fleet.

## Autopilot vs standard scheduling

This is the dominant reason scheduling fields cannot be copy-pasted across clusters.

### Standard GKE clusters

Use:
- `nodeSelector.dedicated: <pool-tag>`
- `tolerations[].key: dedicated`
- Node pools are explicitly provisioned per workload class.

### Autopilot clusters

Use:
- `nodeSelector."cloud.google.com/compute-class": <ComputeClass-name>`
- `tolerations[].key: cloud.google.com/compute-class` (when applicable)
- A `ComputeClass` raw manifest is dropped at `helm-overrides/<cluster>/<app>/computeclass/*-cc.yaml` to declare the class. See [`../docs/platform/schemas/raw-manifest-sidecar-schema.md`](../docs/platform/schemas/raw-manifest-sidecar-schema.md).

Mismatched fields → pods strand on the wrong nodes or stay `Pending`. Diagnosis flow: [`../docs/platform/runbooks/pod-pending-scheduling.md`](../docs/platform/runbooks/pod-pending-scheduling.md). Background: [`../wiki/analyses/ADR-A3-per-cluster-scheduling.md`](../wiki/analyses/ADR-A3-per-cluster-scheduling.md).

## Multi-Contour scheduling

Multi-Contour clusters run `contour-external`, `contour-external-1`, `contour-internal-0`, `contour-internal-1`, `contour-internal-intra-0`, `contour-internal-intra-1` — each a separate Helm release pinned to its own node pool / dedicated taint or compute class. The per-cluster matrix (which Contour goes where) is documented in the repo-root `contour-nodeselector-tolerations-summary.md`. **Always cross-reference that file before touching a Contour values override.**

## Cluster onboarding

Adding a new cluster directory is Layer-1 *high-risk*. The procedure (paired PR with the sister repo's `ApplicationSet`) is in [`../docs/platform/procedures/onboard-new-cluster.md`](../docs/platform/procedures/onboard-new-cluster.md).

## Cluster deboarding

Removing a cluster is rare and requires draining Argo Applications first. There is no in-repo procedure today; escalate to the primary owner — see [`../docs/global/escalation-matrix.md`](../docs/global/escalation-matrix.md).

## See also

- [`./03-chart-inventory.md`](./03-chart-inventory.md) — versioned siblings + multi-Contour pattern
- [`./04-override-hierarchy.md`](./04-override-hierarchy.md) — how cluster + chart compose
- [`./07-singletons-and-blast-radius.md`](./07-singletons-and-blast-radius.md) — `manifests/priorityclass/<cluster>/`
- [`../contour-nodeselector-tolerations-summary.md`](../contour-nodeselector-tolerations-summary.md)