This example shows Feast reading Chronon-backed features in two modes:

• Offline historical retrieval from a Chronon materialization exported as Parquet.
• Online retrieval from a live Chronon quickstart service.

uv run python examples/chronon/run_demo.py --offline-only

The pinned quickstart Docker image is ARM64. Use an ARM64 Docker host (as in the integration workflow), or provide a compatible image for your host with CHRONON_QUICKSTART_IMAGE. Docker must be running and accessible to your user. The launcher uses MongoDB 7.0; CHRONON_MONGO_IMAGE overrides that image.

Install sbt and a JDK. On macOS with Homebrew, this is enough:

brew install sbt openjdk@11
export JAVA_HOME=/opt/homebrew/opt/openjdk@11/libexec/openjdk.jdk/Contents/Home

Build Chronon at the commit used by Feast's Chronon integration workflow:

git clone https://github.com/airbnb/chronon.git /tmp/chronon
git -C /tmp/chronon checkout 6c0b8de9f0301521baf61a46ff3083c566fb4052  # pragma: allowlist secret

cd /tmp/chronon/quickstart/mongo-online-impl
sbt assembly

cd /tmp/chronon
sbt "project service" assembly

Start the local quickstart stack and Chronon service:

CHRONON_REPO=/tmp/chronon \
JAVA_BIN="${JAVA_HOME}/bin/java" \
infra/scripts/chronon/start-local-chronon-service.sh

If port 9000 is already in use, choose another port and pass the same URL to the demo:

CHRONON_REPO=/tmp/chronon \
CHRONON_SERVICE_PORT=19000 \
JAVA_BIN="${JAVA_HOME}/bin/java" \
infra/scripts/chronon/start-local-chronon-service.sh

CHRONON_SERVICE_URL=http://127.0.0.1:19000 \
uv run python examples/chronon/run_demo.py

The richer checkout-risk scenario registers a Feast FeatureService over Chronon's quickstart/training_set.v2 join, fetches multiple users from the live Chronon service, and prints a small risk summary from purchase and refund aggregates:

CHRONON_SERVICE_URL=http://127.0.0.1:19000 \
uv run python examples/chronon/run_demo.py --scenario checkout-risk

By default it retrieves users 5, 7, and 999999. The first two should return Chronon quickstart aggregates; 999999 demonstrates how Feast surfaces a known entity key with missing Chronon features. You can choose different users:

CHRONON_SERVICE_URL=http://127.0.0.1:19000 \
uv run python examples/chronon/run_demo.py \
  --scenario checkout-risk \
  --online-only \
  --user-ids 5,7,999999

Stop the local stack when done:

infra/scripts/chronon/stop-local-chronon-service.sh