#Cell

A cell is the cattle pen: a placement-and-grouping unit over entities of one EntityType. Cells carry a placement policy (how to rank members when recommending where a new tenant should land) and fleet-wide capacity constraints. Phase: schema.

A cell's members are entities of its entityType — for example, a prod-clusters cell whose members are TenantCluster entities. When an Action declares a recommendation against a cell, Terrantula ranks the members by the cell's policy and proposes the best target.

#Minimal example

kind: Cell
name: prod-clusters
entityType: TenantCluster

#Fields

#CellConstraint

A ceiling on an aggregate of a member metric across the whole cell.

#Membership

Derived-membership rule. When membership.derivedFrom is present, the cell computes its members from a member entity's property value rather than from explicit membership rows.

#Annotated example

The prod-clusters cell from the SaaS-tenants demo. Members are TenantCluster entities; placement uses least-loaded ranking by tenant-count; a fleet-wide cap of 500 tenants is enforced across the whole cell.

apiVersion: terrantula.io/v1
kind: Cell
metadata:
  name: prod-clusters
spec:
  displayName: Production cluster fleet
  entityType: TenantCluster
  placementPolicy: least-loaded
  constraints:
    - metric: tenant-count
      aggregate: sum
      max: 500

A derived-membership cell — clusters whose region property equals us-east-1 are automatically members, no membership rows required:

kind: Cell
name: us-east-1
entityType: TenantCluster
membership:
  derivedFrom:
    property: region
    value: us-east-1

#Caveats

#Related

• EntityType — declares the members' type, properties, and metrics.
• Action — recommendations[].cell ranks members for placement.
• Define your first cell · Core Concepts