7 — OpenLineage & Materialization

Both spec.openlineage and spec.materialization are written into feature_store.yaml for all service pods — they apply to the online server, offline server, registry, and materialization jobs alike.

---

OpenLineage Data Lineage (spec.openlineage)

OpenLineage emits data lineage events during feast apply (registry changes) and materialization. Events go outbound from Feast pods to your OpenLineage-compatible backend (Marquez, any OpenLineage HTTP endpoint, Kafka, or a file). No inbound ports or additional Kubernetes Services are required.

Dependency: the Feast image must include feast[openlineage] (openlineage-python).

HTTP transport (Marquez)

apiVersion: feast.dev/v1
kind: FeatureStore
metadata:
  name: sample-openlineage
spec:
  feastProject: my_project
  openlineage:
    enabled: true
    transportType: http
    transportUrl: "http://marquez.feast.svc.cluster.local:5000"
    transportEndpoint: "api/v1/lineage"
    extraConfig:
      namespace: "my-feast-project"
      producer: "feast-operator"
      emit_on_apply: "true"
      emit_on_materialize: "true"

HTTP with API key authentication

apiVersion: v1
kind: Secret
metadata:
  name: openlineage-secret
  namespace: feast
stringData:
  api_key: "<your-api-key>"
---
apiVersion: feast.dev/v1
kind: FeatureStore
metadata:
  name: sample-openlineage-auth
  namespace: feast
spec:
  feastProject: my_project
  openlineage:
    enabled: true
    transportType: http
    transportUrl: "https://marquez.example.com"
    transportEndpoint: "api/v1/lineage"
    apiKeySecretRef:
      name: openlineage-secret    # Secret must contain key "api_key"
    extraConfig:
      namespace: "my-feast-project"
      emit_on_apply: "true"
      emit_on_materialize: "true"

The operator reads the api_key value from the Secret and writes it into feature_store.yaml. The Secret must be in the same namespace as the FeatureStore.

Kafka transport

openlineage:
  enabled: true
  transportType: kafka
  extraConfig:
    namespace: "my-feast-project"
    emit_on_apply: "true"
    emit_on_materialize: "true"
    bootstrap_servers: "kafka.svc:9092"
    topic: "openlineage"
    sasl_mechanism: "PLAIN"

Console transport (development)

Events are printed to stdout — useful for verifying integration without a backend:

openlineage:
  enabled: true
  transportType: console
  extraConfig:
    emit_on_apply: "true"
    emit_on_materialize: "true"

Field reference

Field	Type	Description
enabled	bool	Activates OpenLineage. Must be true
transportType	string	http / console / file / kafka
transportUrl	string	Base URL for HTTP transport
transportEndpoint	string	API path appended to transportUrl
apiKeySecretRef.name	string	Name of a Secret containing key api_key
extraConfig	map[string]string	Additional settings (see below)

extraConfig keys

Values that are "true" or "false" are automatically coerced to native YAML booleans so that Feast's Pydantic StrictBool validators accept them.

Key	Type	Description
namespace	string	OpenLineage namespace for emitted events
producer	string	Producer identifier in emitted events
emit_on_apply	bool string	Emit events on feast apply
emit_on_materialize	bool string	Emit events on materialization
bootstrap_servers	string	Kafka: comma-separated broker addresses
topic	string	Kafka: target topic name
sasl_mechanism	string	Kafka: SASL mechanism (e.g. PLAIN, SCRAM-SHA-256)
file_path	string	File transport: path to write lineage events

---

Materialization (spec.materialization)

Controls how features are written to the online store during materialization jobs. Settings are written into feature_store.yaml for all pods.

spec:
  materialization:
    onlineWriteBatchSize: 10000
    extraConfig:
      pull_latest_features: "false"

onlineWriteBatchSize

Limits the number of rows written per batch during materialization. Without this, all rows for a feature view are written in a single batch — this can cause OOM for large feature views.

• Supported engines: local, Spark, Ray

• Minimum value: 1 (enforced by CRD validation)

materialization:
  onlineWriteBatchSize: 10000    # 10 k rows per batch

extraConfig

Passes additional MaterializationConfig settings inline. Boolean strings ("true" / "false") are coerced to native YAML booleans.

materialization:
  extraConfig:
    pull_latest_features: "false"    # only materialize the latest value per entity

Key	Type	Description
pull_latest_features	bool string	When "true", only the latest feature value per entity is materialized. Default is engine-dependent

---

Full example

apiVersion: v1
kind: Secret
metadata:
  name: openlineage-secret
  namespace: feast
stringData:
  api_key: "<your-api-key>"
---
apiVersion: feast.dev/v1
kind: FeatureStore
metadata:
  name: feast-production
  namespace: feast
spec:
  feastProject: my_project
  materialization:
    onlineWriteBatchSize: 10000
  openlineage:
    enabled: true
    transportType: http
    transportUrl: "http://marquez.feast.svc.cluster.local:5000"
    transportEndpoint: "api/v1/lineage"
    apiKeySecretRef:
      name: openlineage-secret
    extraConfig:
      namespace: "my-feast-project"
      producer: "feast-operator"
      emit_on_apply: "true"
      emit_on_materialize: "true"
  services:
    onlineStore:
      server: {}

---

See also

• API reference — OpenLineageConfig

• API reference — MaterializationConfig

• Sample: materialization + openlineage

• Feast SDK — OpenLineage

• Guide 6 — Batch Engine & Scheduled Jobs