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Architecture

Topograph consists of five major components:

  1. API Server
  2. Node Observer
  3. Node Data Broker
  4. Provider
  5. Engine

Design

Components

1. API Server

The API Server receives topology generation requests and returns results asynchronously. Requests are aggregated over a configurable delay window so that a burst of node changes (common during cluster scaling events) produces a single topology update rather than a storm.

2. Node Observer

The Node Observer is used in Kubernetes deployments. It is a controller that monitors configured node and pod changes, and it also watches the Topograph API pod. When the node-data-broker is enabled, it additionally watches the broker DaemonSet's lifecycle, desired replica count, and readiness. Relevant events enqueue one cluster-wide topology key in a rate-limited work queue, coalescing bursts into idempotent reconciliation. Reconciliation waits for the broker DaemonSet's ready replica count to match its desired count before asking the API Server to generate a new topology configuration, and it requeues failed requests.

3. Node Data Broker

The Node Data Broker is also used when Topograph is deployed in a Kubernetes cluster. It collects relevant node attributes and stores them as node annotations.

4. Provider

The Provider interfaces with CSPs or on-premises tools to retrieve topology-related data from the cluster and converts it into an internal representation. Providers may compose network-fabric discovery with an independent accelerator-domain source; for example, the InfiniBand provider can combine ibnetdiscover with nvidia-smi, a Kubernetes Node label, or no accelerator source.

5. Engine

The Engine translates this internal representation into the format expected by the workload manager.

Workflow

  • The API Server listens on the port and notifies the Provider about incoming requests. In Kubernetes, the incoming requests are sent by the Node Observer, which watches selected node/pod status and API-server readiness.
  • The Provider receives notifications and invokes CSP API to retrieve topology-related information.
  • The Engine converts the topology information into the format expected by the user cluster (e.g., SLURM or Kubernetes).