feat: Add Java OpenFeature provider

.github/workflows/release-please.yml

@@ -127,5 +127,3 @@ jobs:
           platforms: linux/amd64
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
-
-

.gitignore

@@ -1,5 +1,8 @@
+# Ignore generated protobuf Java sources vendored during local build
+openfeature-provider/java/src/main/java/com/spotify/confidence/wasm/Messages.java
 .DS_Store
 *.stamp
+.idea/
 
 target/
 wasm/confidence_resolver.wasm

.release-please-manifest.json

@@ -1 +1 @@
-{"confidence-resolver":"0.5.2","confidence-cloudflare-resolver":"0.2.7","wasm-msg":"0.2.0","wasm/rust-guest":"0.1.8"}
+{"confidence-resolver":"0.5.2","confidence-cloudflare-resolver":"0.2.7","wasm-msg":"0.2.0","wasm/rust-guest":"0.1.8","openfeature-provider-local-java":"0.6.4"}

Dockerfile

@@ -400,6 +400,54 @@ FROM openfeature-provider-js-base AS openfeature-provider-js.build
 
 RUN make build
 
+# ==============================================================================
+# OpenFeature Provider (Java) - Build and test
+# ==============================================================================
+FROM eclipse-temurin:17-jdk AS openfeature-provider-java-base
+
+# Install Maven and protobuf (Debian-based for glibc compatibility)
+RUN apt-get update && apt-get install -y \
+    maven \
+    protobuf-compiler \
+    make \
+  && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+
+# Copy pom.xml for dependency caching
+COPY openfeature-provider/java/pom.xml ./
+COPY openfeature-provider/java/Makefile ./
+
+# Download dependencies (this layer will be cached)
+RUN mvn dependency:go-offline -q || true
+
+# Copy proto files (needed for protobuf generation)
+COPY confidence-resolver/protos ../../confidence-resolver/protos/
+COPY wasm/proto ../../wasm/proto/
+
+# Copy source code
+COPY openfeature-provider/java/src ./src/
+
+# Copy WASM module into resources
+COPY --from=wasm-rust-guest.artifact /confidence_resolver.wasm ./src/main/resources/wasm/confidence_resolver.wasm
+
+# Set environment variable
+ENV IN_DOCKER_BUILD=1
+
+# ==============================================================================
+# Test OpenFeature Provider (Java)
+# ==============================================================================
+FROM openfeature-provider-java-base AS openfeature-provider-java.test
+
+RUN make test
+
+# ==============================================================================
+# Build OpenFeature Provider (Java)
+# ==============================================================================
+FROM openfeature-provider-java-base AS openfeature-provider-java.build
+
+RUN make build
+
 # ==============================================================================
 # All - Build and validate everything (default target)
 # ==============================================================================
@@ -411,7 +459,8 @@ COPY --from=wasm-rust-guest.artifact /confidence_resolver.wasm /artifacts/wasm/
 # Force test stages to run by copying marker files
 COPY --from=confidence-resolver.test /workspace/Cargo.toml /markers/test-resolver
 COPY --from=wasm-msg.test /workspace/Cargo.toml /markers/test-wasm-msg
-COPY --from=openfeature-provider-js.test /app/package.json /markers/test-openfeature
+COPY --from=openfeature-provider-js.test /app/package.json /markers/test-openfeature-js
+COPY --from=openfeature-provider-java.test /app/pom.xml /markers/test-openfeature-java
 
 # Force integration test stages to run (host examples)
 COPY --from=node-host.test /app/package.json /markers/integration-node
@@ -425,5 +474,6 @@ COPY --from=wasm-msg.lint /workspace/Cargo.toml /markers/lint-wasm-msg
 COPY --from=wasm-rust-guest.lint /workspace/Cargo.toml /markers/lint-guest
 
 # Force build stages to run
-COPY --from=openfeature-provider-js.build /app/dist/index.node.js /artifacts/openfeature/
+COPY --from=openfeature-provider-js.build /app/dist/index.node.js /artifacts/openfeature-js/
+COPY --from=openfeature-provider-java.build /app/target/*.jar /artifacts/openfeature-java/
 COPY --from=confidence-cloudflare-resolver.lint /workspace/Cargo.toml /markers/lint-cloudflare

Makefile

@@ -16,12 +16,14 @@ test:
 	$(MAKE) -C confidence-resolver test
 	$(MAKE) -C wasm-msg test
 	$(MAKE) -C openfeature-provider/js test
+	$(MAKE) -C openfeature-provider/java test
 
 integration-test:
 	$(MAKE) -C wasm/node-host run
 	$(MAKE) -C wasm/java-host run
 	$(MAKE) -C wasm/go-host run
 	$(MAKE) -C wasm/python-host run
+	$(MAKE) -C wasm/java-host run
 
 
 lint:
@@ -33,6 +35,7 @@ lint:
 
 build: wasm/confidence_resolver.wasm
 	$(MAKE) -C openfeature-provider/js build
+	$(MAKE) -C openfeature-provider/java build
 
 all: lint test build
 	@echo "✅ All checks passed!"
@@ -44,5 +47,6 @@ clean:
 	$(MAKE) -C wasm/go-host clean
 	$(MAKE) -C wasm/python-host clean
 	$(MAKE) -C openfeature-provider/js clean
+	$(MAKE) -C openfeature-provider/java clean
 
 .DEFAULT_GOAL := all

confidence-resolver/protos/google/api/httpbody.proto

@@ -0,0 +1,18 @@
+syntax = "proto3";
+
+package google.api;
+
+import "google/protobuf/any.proto";
+
+option java_package = "com.google.api";
+option java_multiple_files = true;
+option java_outer_classname = "HttpBodyProto";
+
+// Minimal HttpBody to satisfy imports during local builds
+message HttpBody {
+  string content_type = 1;
+  bytes data = 2;
+  repeated google.protobuf.Any extensions = 3;
+}
+
+

openfeature-provider/java/Makefile

@@ -0,0 +1,59 @@
+# openfeature-provider/java Makefile
+# Java OpenFeature local provider
+
+ROOT := $(realpath $(CURDIR)/../..)
+
+# Stamps and inputs
+BUILD_STAMP := .build.stamp
+INSTALL_STAMP := .install.stamp
+SRC := $(shell find src -name '*.java' 2>/dev/null)
+RESOURCES_WASM := src/main/resources/wasm/confidence_resolver.wasm
+LOCAL_WASM := $(ROOT)/wasm/confidence_resolver.wasm
+GEN_MESSAGES := target/generated-sources/protobuf/java/com/spotify/confidence/wasm/Messages.java
+
+.PHONY: install build test clean
+
+# Always build/copy wasm when not in Docker; inside Docker we rely on COPY from Dockerfile
+ifneq ($(IN_DOCKER_BUILD),1)
+.PHONY: $(LOCAL_WASM)
+
+$(LOCAL_WASM):
+	$(MAKE) -C $(ROOT) wasm/confidence_resolver.wasm
+
+$(RESOURCES_WASM): $(LOCAL_WASM)
+	@mkdir -p $(dir $@)
+	cp $(LOCAL_WASM) $@
+else
+# In Docker, the WASM is already copied into src/main/resources by the Dockerfile
+$(RESOURCES_WASM):
+	@mkdir -p $(dir $@)
+	@test -f $@ || (echo "Missing $@ (expected via Docker COPY)"; exit 1)
+endif
+
+# A lightweight install target to prep resources
+$(INSTALL_STAMP): pom.xml $(RESOURCES_WASM)
+	touch $@
+
+
+$(BUILD_STAMP): $(INSTALL_STAMP) pom.xml $(SRC)
+	mvn -q -DskipTests protobuf:compile
+	@if [ -f "$(GEN_MESSAGES)" ]; then \
+		mkdir -p src/main/java/com/spotify/confidence/wasm; \
+		cp $(GEN_MESSAGES) src/main/java/com/spotify/confidence/wasm/Messages.java; \
+	fi
+	mvn -q -DskipTests package
+	touch $@
+
+install: $(INSTALL_STAMP)
+
+build: $(BUILD_STAMP)
+
+test: $(INSTALL_STAMP)
+	mvn -q test
+
+clean:
+	mvn -q clean
+	rm -f $(BUILD_STAMP) $(INSTALL_STAMP)
+	rm -f $(RESOURCES_WASM)
+
+

openfeature-provider/java/README.md

@@ -0,0 +1,101 @@
+# Confidence OpenFeature Local Provider
+
+![Status: Experimental](https://img.shields.io/badge/status-experimental-orange)
+
+A high-performance OpenFeature provider for [Confidence](https://confidence.spotify.com/) feature flags that evaluates flags locally for minimal latency.
+
+## Features
+
+- **Local Resolution**: Evaluates feature flags locally using WebAssembly (WASM)
+- **Low Latency**: No network calls during flag evaluation
+- **Automatic Sync**: Periodically syncs flag configurations from Confidence
+- **Exposure Logging**: Fully supported exposure logging (and other resolve analytics)
+- **OpenFeature Compatible**: Works with the standard OpenFeature SDK
+
+## Installation
+
+Add this dependency to your `pom.xml`:
+<!-- x-release-please-start-version -->
+```xml
+<dependency>
+    <groupId>com.spotify.confidence</groupId>
+    <artifactId>openfeature-provider-local</artifactId>
+    <version>0.6.4</version>
+</dependency>
+```
+<!-- x-release-please-end -->
+
+## Quick Start
+
+```java
+import com.spotify.confidence.ApiSecret;
+import com.spotify.confidence.OpenFeatureLocalResolveProvider;
+import dev.openfeature.sdk.OpenFeatureAPI;
+import dev.openfeature.sdk.Client;
+
+// Create API credentials
+ApiSecret apiSecret = new ApiSecret("your-client-id", "your-client-secret");
+String clientSecret = "your-application-client-secret";
+
+// Create and register the provider
+OpenFeatureLocalResolveProvider provider = 
+    new OpenFeatureLocalResolveProvider(apiSecret, clientSecret);
+OpenFeatureAPI.getInstance().setProvider(provider);
+
+// Use OpenFeature client
+Client client = OpenFeatureAPI.getInstance().getClient();
+String value = client.getStringValue("my-flag", "default-value");
+```
+
+## Configuration
+
+
+### Exposure Logging
+
+Enable or disable exposure logging:
+
+```java
+// Enable exposure logging (default)
+new OpenFeatureLocalResolveProvider(apiSecret, clientSecret, true);
+
+// Disable exposure logging
+new OpenFeatureLocalResolveProvider(apiSecret, clientSecret, false);
+```
+
+## Credentials
+
+You need two types of credentials:
+
+1. **API Secret** (`ApiSecret`): For authenticating with the Confidence API
+   - Contains `clientId` and `clientSecret` for your Confidence application
+
+2. **Client Secret** (`String`): For flag resolution authentication
+   - Application-specific secret for flag evaluation
+
+Both can be obtained from your Confidence dashboard.
+
+## Sticky Resolve
+
+The provider supports **Sticky Resolve** for consistent variant assignments across flag evaluations. This ensures users receive the same variant even when their targeting attributes change, and enables pausing experiment intake.
+
+**By default, sticky assignments are managed by Confidence servers.** When sticky assignment data is needed, the provider makes a network call to Confidence, which maintains the sticky repository server-side with automatic 90-day TTL management. This is a fully supported production approach that requires no additional setup.
+
+
+Optionally, you can implement a custom `MaterializationRepository` to manage sticky assignments in your own storage (Redis, database, etc.) to eliminate network calls and improve latency:
+
+```java
+// Optional: Custom storage for sticky assignments
+MaterializationRepository repository = new RedisMaterializationRepository(jedisPool, "myapp");
+OpenFeatureLocalResolveProvider provider = new OpenFeatureLocalResolveProvider(
+    apiSecret,
+    clientSecret,
+    repository
+);
+```
+
+For detailed information on how sticky resolve works and how to implement custom storage backends, see [STICKY_RESOLVE.md](STICKY_RESOLVE.md).
+
+## Requirements
+
+- Java 17+
+- OpenFeature SDK 1.6.1+