Initial implementation (#2)

* Initialize crate

* chore: add CI configuration

* feat: add initial API and noop implementation

* test: add Makefile to pull test data

* feat: Universal Flag Configuration parser

* feat: rules evaluation

* feat: sharder

* feat: eval

* test: integrate sdk-test-data test for eval

* feat: configuration store

* refactor: Ufc -> UniversalFlagConfig

* feat: add configuration poller

* feat: add logging and error handling

.github/workflows/ci.yml

@@ -0,0 +1,24 @@
+name: Cargo Build & Test
+
+on:
+  push:
+  pull_request:
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  build_and_test:
+    name: Build & Test
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        toolchain:
+          - stable
+    steps:
+      - uses: actions/checkout@v3
+      - run: make test-data
+      - run: rustup update ${{ matrix.toolchain }} && rustup default ${{ matrix.toolchain }}
+      - run: cargo build --verbose
+      - run: cargo test --verbose
+      - run: cargo doc --verbose

.gitignore

@@ -1,7 +1,7 @@
 # Generated by Cargo
 # will have compiled files and executables
-debug/
-target/
+/debug/
+/target/
 
 # Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
 # More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
@@ -12,3 +12,5 @@ Cargo.lock
 
 # MSVC Windows builds of rustc generate these, which store debugging information
 *.pdb
+
+/tests/data/

Cargo.toml

@@ -0,0 +1,30 @@
+[package]
+name = "eppo"
+version = "0.1.0"
+edition = "2021"
+description = "Eppo SDK for Rust"
+homepage = "https://docs.geteppo.com/sdks/server-sdks/rust"
+repository = "https://github.com/Eppo-exp/rust-sdk"
+license = "MIT"
+keywords = ["eppo", "feature-flags"]
+categories = ["config"]
+
+[dependencies]
+chrono = { version = "0.4.38", features = ["serde"] }
+derive_more = "0.99.17"
+log = { version = "0.4.21", features = ["kv", "kv_serde"] }
+md5 = "0.7.0"
+rand = "0.8.5"
+regex = "1.10.4"
+reqwest = { version = "0.12.4", features = ["blocking", "json"] }
+semver = { version = "1.0.22", features = ["serde"] }
+serde = { version = "1.0.198", features = ["derive"] }
+serde_json = "1.0.116"
+thiserror = "1.0.60"
+url = "2.5.0"
+
+[[example]]
+name = "simple"
+
+[dev-dependencies]
+env_logger = { version = "0.11.3", features = ["unstable-kv"] }

Makefile

@@ -0,0 +1,41 @@
+# Make settings - @see https://tech.davis-hansson.com/p/make/
+SHELL := bash
+.ONESHELL:
+.SHELLFLAGS := -eu -o pipefail -c
+.DELETE_ON_ERROR:
+MAKEFLAGS += --warn-undefined-variables
+MAKEFLAGS += --no-builtin-rules
+
+# Log levels
+DEBUG := $(shell printf "\e[2D\e[35m")
+INFO  := $(shell printf "\e[2D\e[36m🔵 ")
+OK    := $(shell printf "\e[2D\e[32m🟢 ")
+WARN  := $(shell printf "\e[2D\e[33m🟡 ")
+ERROR := $(shell printf "\e[2D\e[31m🔴 ")
+END   := $(shell printf "\e[0m")
+
+.PHONY: default
+default: help
+
+## help - Print help message.
+.PHONY: help
+help: Makefile
+	@echo "usage: make <target>"
+	@sed -n 's/^##//p' $<
+
+## test-data
+testDataDir := tests/data/
+branchName := main
+githubRepoLink := https://github.com/Eppo-exp/sdk-test-data.git
+.PHONY: test-data
+test-data:
+	rm -rf ${testDataDir}
+	git clone -b ${branchName} --depth 1 --single-branch ${githubRepoLink} ${testDataDir}
+
+${testDataDir}:
+	rm -rf ${testDataDir}
+	git clone -b ${branchName} --depth 1 --single-branch ${githubRepoLink} ${testDataDir}
+
+.PHONY: test
+test: ${testDataDir}
+	cargo test

examples/simple/main.rs

@@ -0,0 +1,29 @@
+use std::collections::HashMap;
+
+pub fn main() -> eppo::Result<()> {
+    env_logger::Builder::from_env(env_logger::Env::new().default_filter_or("eppo")).init();
+
+    let api_key = std::env::var("EPPO_API_KEY").unwrap();
+    let mut client = eppo::ClientConfig::from_api_key(api_key).to_client();
+
+    // Start a poller thread to fetch configuration from the server.
+    let poller = client.start_poller_thread()?;
+
+    // Block waiting for configuration. Until this call returns, the client will return None for all
+    // assignments.
+    if let Err(err) = poller.wait_for_configuration() {
+        println!("error requesting configuration: {:?}", err);
+    }
+
+    // Get assignment for test-subject.
+    let assignment = client
+        .get_assignment("a-boolean-flag", "test-subject", &HashMap::new())
+        .unwrap_or_default()
+        .and_then(|x| x.as_boolean())
+        // default assignment
+        .unwrap_or(false);
+
+    println!("Assignment: {:?}", assignment);
+
+    Ok(())
+}

src/assignment_logger.rs

@@ -0,0 +1,35 @@
+use std::collections::HashMap;
+
+use serde::{Deserialize, Serialize};
+
+use crate::SubjectAttributes;
+
+#[derive(Debug, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct AssignmentEvent {
+    pub feature_flag: String,
+    pub allocation: String,
+    pub experiment: String,
+    pub variation: String,
+    pub subject: String,
+    pub subject_attributes: SubjectAttributes,
+    pub timestamp: String,
+    pub meta_data: HashMap<String, String>,
+    #[serde(flatten)]
+    pub extra_logging: HashMap<String, String>,
+}
+
+pub trait AssignmentLogger {
+    fn log_assignment(&self, event: AssignmentEvent);
+}
+
+pub(crate) struct NoopAssignmentLogger;
+impl AssignmentLogger for NoopAssignmentLogger {
+    fn log_assignment(&self, _event: AssignmentEvent) {}
+}
+
+impl<T: Fn(AssignmentEvent)> AssignmentLogger for T {
+    fn log_assignment(&self, event: AssignmentEvent) {
+        self(event);
+    }
+}