The higher level Development Guide gives contributing to Feast codebase as a whole.

This guide is targeted at developers looking to contribute to Feast components in the feast-java Repository:

• Feast Serving
• Feast Serving Client

Don't see the Feast component that you want to contribute to here?
Check out the Development Guide to learn how Feast components are distributed over multiple repositories.

There are four key top level packages:

• serving: Feast Serving (a gRPC service to serve features)
• serving-client: Feast Serving Client (a thin Java client to communicate with Feast serving via gRPC )
• datatypes: A symlink to the overall project protos. These include the core serving gRPC protos, proto representations of all objects in the Feast registry.
• coverage: Generates JaCoCo coverage reports

Note: there are references to metrics collection in the code. These are unused and exist for legacy reasons (from when this used Spring Boot), but remain in the code until published to StatsD / Prometheus Pushgateway.

The primary entrypoint into the Feast Serving server is ServingGuiceApplication, which connects to the rest of the packages:

• connectors: Contains online store connectors (e.g. Redis)
• exception: Contains user-facing exceptions thrown by Feast Serving
• registry: Logic to parse a Feast file-based registry (in GCS, S3, or local) into the Registry proto object, and automatically re-sync the registry.
• service: Core logic that exposes and backs the serving APIs. This includes communication with a feature transformation server to execute on demand transformations
  • The root code in this package creates the main entrypoint (ServingServiceV2) which is injected into OnlineServingGrpcServiceV2 in grpc/ implement the gRPC service.
  • config: Guice modules to power the server and config
    • Includes server config / guice modules in ServerModule
    • Maps overall Feast Serving user configuration from Java to YAML in ApplicationPropertiesModule and ApplicationProperties
  • controller: server controllers (right now, only a gRPC health check)
  • grpc: Implementation of the gRPC serving service
  • interceptors: gRPC interceptors (currently used to produce metrics around each gRPC request)

Common Environment Setup for all feast-java Feast components:

Ensure following development tools are installed:

• Java SE Development Kit 11 (you may need to do export JAVA_HOME=$(/usr/libexec/java_home -v 11))
• Maven 3.6
• make

Feast's Java codebase conforms to the Google Java Style Guide.

Automatically format the code to conform the style guide by:

# formats all code in the feast-java repository
make format-java

If you're using IntelliJ, you can import these code style settings if you'd like to use the IDE's reformat function.

The Project Makefile provides useful shorthands for common development tasks:

Note: These commands rely on a local version of feast (Python) to be installed

Run all Unit tests:

make test-java

Run all Integration tests:

make test-java-integration

Building Docker images for Feast Serving:

make build-docker REGISTRY=gcr.io/kf-feast VERSION=develop

If you're using IntelliJ, some additional steps may be needed to make sure IntelliJ autocomplete works as expected. Specifically, proto-generated code is not indexed by IntelliJ. To fix this, navigate to the following window in IntelliJ: Project Structure > Modules > datatypes-java, and mark the following folders as Source directorys:

• target/generated-sources/protobuf/grpc-java
• target/generated-sources/protobuf/java
• target/generated-sources/annotations

See instructions here for developing.

Setting up your development environment:

1. Complete the feast-java Common Setup

Feast Serving Client is a Serving Client for retrieving Features from a running Feast Serving instance.
See the Feast Serving Section section for how to get a Feast Serving instance running.

1. Build / Compile Feast Java Client with Maven:

mvn package -pl sdk/java --also-make -Dmaven.test.skip=true

Unit Tests can be used to verify functionality:

mvn package -pl sdk/java test --also-make