Contributor Onboarding Guide

Welcome to CoSky. This guide will take you from zero to productive contributor. You are expected to know Kotlin or Java, be comfortable with Spring Boot, and have a basic understanding of Redis. Everything else you will learn here.

Part I — Foundations

What is CoSky?

CoSky is a high-performance microservice governance platform that provides service discovery and configuration management, backed entirely by Redis. Instead of deploying a separate coordination server (like etcd, Consul, or ZooKeeper), CoSky turns your existing Redis infrastructure into a service mesh control plane.

The name comes from Co (configuration) + Sky (service discovery). The project is open-source under Apache 2.0.

Repository: https://github.com/Ahoo-Wang/CoSky
Group ID: me.ahoo.cosky
Current version: 5.5.8

Tech Stack

Layer	Technology
Language	Kotlin (JVM 17 toolchain)
Framework	Spring Boot 3.x, Spring Cloud
Reactive	Project Reactor (`Mono`/`Flux`)
Storage	Redis (via `ReactiveStringRedisTemplate`)
Atomicity	Lua scripts for all mutations
Build	Gradle (Kotlin DSL)
Testing	JUnit 5, MockK, FluentAssert
Code Style	Detekt
Benchmarks	JMH (Java Microbenchmark Harness)

Building the Project

bash

# Clone the repository
git clone https://github.com/Ahoo-Wang/CoSky.git
cd CoSky

# Build everything (compile + test)
./gradlew build

# Build without tests (faster for development)
./gradlew build -x test

# Check code style
./gradlew detekt

# Run specific module tests
./gradlew :cosky-config:test
./gradlew :cosky-discovery:test

# Run the REST API server locally
./gradlew :cosky-rest-api:bootRun

# Run benchmarks
./gradlew :cosky-config:jmh
./gradlew :cosky-discovery:jmh

Redis Requirement

Integration tests require a running Redis instance. The test base class AbstractReactiveRedisTest connects to localhost:6379 by default. Start Redis before running tests:

bash

# Docker
docker run -d -p 6379:6379 redis:latest

# Or via Homebrew
brew services start redis

Part II — Architecture and Domain

Module Structure

CoSky is organized as a multi-module Gradle project. Understanding the dependency graph is essential before making changes.

mermaid

flowchart TB
    subgraph "Core Layer"
        CORE["cosky-core<br>Namespace, Redis keys,<br>PubSub base"]
    end

    subgraph "Domain Layer"
        CONFIG["cosky-config<br>Configuration CRUD,<br>versioning, rollback"]
        DISCOVERY["cosky-discovery<br>Service registry,<br>discovery, load balancing"]
    end

    subgraph "Spring Cloud Layer"
        SCCORE["cosky-spring-cloud-core<br>Auto-configuration,<br>shared properties"]
        SCCONFIG["cosky-spring-cloud-starter-config<br>Property source locator,<br>config refresh"]
        SCDISC["cosky-spring-cloud-starter-discovery<br>Service registration,<br>discovery client"]
    end

    subgraph "Server Layer"
        RESTAPI["cosky-rest-api<br>REST controllers,<br>dashboard, RBAC"]
    end

    subgraph "Support"
        BOM["cosky-bom"]
        DEPS["cosky-dependencies"]
        TEST["cosky-test"]
    end

    CONFIG --> CORE
    DISCOVERY --> CORE
    SCCORE --> CORE
    SCCONFIG --> CONFIG
    SCCONFIG --> SCCORE
    SCDISC --> DISCOVERY
    SCDISC --> SCCORE
    RESTAPI --> CONFIG
    RESTAPI --> DISCOVERY

    style CORE fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style CONFIG fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style DISCOVERY fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style SCCORE fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style SCCONFIG fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style SCDISC fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style RESTAPI fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style BOM fill:#2d333b,stroke:#30363d,color:#8b949e
    style DEPS fill:#2d333b,stroke:#30363d,color:#8b949e
    style TEST fill:#2d333b,stroke:#30363d,color:#8b949e

Module	Purpose	Key Interfaces
`cosky-core`	Namespace management, Redis key utilities, PubSub event base	`NamespaceService`, `EventListenerContainer`, `Namespaced`
`cosky-config`	Configuration CRUD, versioning, rollback, consistency caching	`ConfigService`, `ConfigRollback`
`cosky-discovery`	Service registry, discovery, load balancing, topology	`ServiceRegistry`, `ServiceDiscovery`, `LoadBalancer`
`cosky-spring-cloud-core`	Shared Spring Boot auto-configuration	`CoSkyProperties`, `CoSkyAutoConfiguration`
`cosky-spring-cloud-starter-config`	Spring Cloud config loading and refresh	`CoSkyPropertySourceLocator`, `CoSkyConfigRefresher`
`cosky-spring-cloud-starter-discovery`	Spring Cloud service registration and discovery	`CoSkyDiscoveryClient`, `CoSkyAutoServiceRegistration`
`cosky-rest-api`	REST API server, dashboard, security, RBAC	`ServiceController`, `ConfigController`
`cosky-bom`	Bill of Materials for dependency management	—
`cosky-test`	Shared test utilities, Lua cleanup scripts	`AbstractReactiveRedisTest`

Critical rule: cosky-core has zero dependencies on other CoSky modules. The dependency graph must remain acyclic.

The Consistency Pattern: Local Cache + PubSub Invalidation

This is the most important architectural concept in CoSky. Read this carefully.

CoSky achieves extreme read performance by combining:

Local in-process cache — data is stored in ConcurrentHashMap inside each application process. Reads hit this cache at nanosecond speed.
Redis PubSub — when data changes in Redis, a PubSub message notifies all subscribers to invalidate or refresh their local cache.
Lazy subscription — the cache entry is created on first access and automatically subscribes to PubSub events for that key.

mermaid

sequenceDiagram
    autonumber
    participant App1 as Application 1
    participant Redis as Redis
    participant App2 as Application 2

    Note over App1,App2: Initial read (cache miss)
    App1->>Redis: getConfig("database.yaml")
    Redis-->>App1: config data
    App1->>Redis: SUBSCRIBE config changes

    Note over App1,App2: Second application reads
    App2->>Redis: getConfig("database.yaml")
    Redis-->>App2: config data
    App2->>Redis: SUBSCRIBE config changes

    Note over App1,App2: Config update
    App1->>Redis: setConfig("database.yaml", newData)
    Redis->>Redis: Lua script: write + PUBLISH
    Redis-->>App1: PubSub notification
    Redis-->>App2: PubSub notification

    Note over App1,App2: Cache refresh
    App1->>Redis: getConfig("database.yaml")
    App2->>Redis: getConfig("database.yaml")
    App1->>App1: Update local cache
    App2->>App2: Update local cache

The consistency wrappers are:

Config: RedisConsistencyConfigService wraps RedisConfigService — cited at cosky-config/src/main/kotlin/me/ahoo/cosky/config/redis/RedisConsistencyConfigService.kt:33
Discovery: ConsistencyRedisServiceDiscovery wraps RedisServiceDiscovery — cited at cosky-discovery/src/main/kotlin/me/ahoo/cosky/discovery/redis/ConsistencyRedisServiceDiscovery.kt:43

The performance gain is dramatic:

Operation	Direct Redis	With Consistency Layer
`getConfig`	~241K ops/s	~257M ops/s (1000x faster)
`getInstances`	~227K ops/s	~77M ops/s (340x faster)
`getServices`	~305K ops/s	~456M ops/s (1500x faster)

Redis Key Schema

All Redis keys are namespace-scoped. The namespace acts as a tenant delimiter and is wrapped in Redis hash tags {...} for cluster-mode compatibility.

Configuration keys (ConfigKeyGenerator):

Purpose	Key Pattern	Redis Type
Config index	`{namespace}:cfg_idx`	SET
Current config	`{namespace}:cfg:{configId}`	HASH
History index	`{namespace}:cfg_htr_idx:{configId}`	ZSET
History version	`{namespace}:cfg_htr:{configId}:{version}`	HASH

Discovery keys (DiscoveryKeyGenerator):

Purpose	Key Pattern	Redis Type
Service index	`{namespace}:svc_idx`	SET
Service stats	`{namespace}:svc_stat`	HASH
Instance index	`{namespace}:svc_itc_idx:{serviceId}`	SET
Instance data	`{namespace}:svc_itc:{instanceId}`	HASH

Why hash tags? Redis Cluster routes keys to slots based on the text between { and }. Wrapping the namespace ensures all keys for a namespace land on the same shard, enabling atomic cross-key operations via Lua scripts. See cosky-core/src/main/kotlin/me/ahoo/cosky/core/util/RedisKeys.kt:24.

Lua Scripts for Atomic Operations

All write operations execute as Lua scripts inside Redis. This guarantees atomicity — no client can observe a partially-completed state. There are no multi-command transactions in the codebase; everything is a single Lua script call.

Key Lua scripts:

Script	Module	Purpose
`config_set.lua`	cosky-config	Atomic set + version + history + publish
`config_remove.lua`	cosky-config	Atomic remove + history + publish
`config_rollback.lua`	cosky-config	Atomic rollback to target version + publish
`registry_register.lua`	cosky-discovery	Atomic register instance + set TTL + publish
`registry_deregister.lua`	cosky-discovery	Atomic deregister + delete key + publish
`registry_renew.lua`	cosky-discovery	Heart beat renewal with throttled publish
`discovery_get_instances.lua`	cosky-discovery	Read instances + lazy expire dead ones

Each Lua script follows the same pattern:

Read current state
Check preconditions (e.g., hash comparison to skip no-op writes)
Perform mutations
PUBLISH a notification to the key's channel
Return a status code

The throttled publish in registry_renew.lua is particularly interesting — it only publishes a renew event when the previous TTL publication is about to expire, reducing PubSub traffic by an order of magnitude. See cosky-discovery/src/main/resources/registry_renew.lua:8.

The Event Model

CoSky uses Redis PubSub to propagate state changes. Events are string-based op codes published to Redis channels that map directly to key names.

Config events (ConfigChangedEvent):

Event	Trigger	Op Code
`SET`	Config created or updated	`"set"`
`REMOVE`	Config deleted	`"remove"`
`ROLLBACK`	Config rolled back to previous version	`"rollback"`

Instance events (InstanceChangedEvent):

Event	Trigger	Op Code
`REGISTER`	New instance registered	`"register"`
`DEREGISTER`	Instance explicitly removed	`"deregister"`
`EXPIRED`	Instance TTL expired (lazy cleanup)	`"expired"`
`RENEW`	Instance heartbeat renewed TTL	`"renew"`
`SET_METADATA`	Instance metadata updated	`"set_metadata"`

Part III — Contributing

Development Environment Setup

mermaidmermaid flowchart TD CLONE["Clone repo
git clone https://github.com/Ahoo-Wang/CoSky"] --> JDK["Install JDK 17
brew install openjdk@17"] JDK --> REDIS["Start Redis
docker run -d -p 6379:6379 redis"] REDIS --> BUILD["Build project
./gradlew build"] BUILD --> IDE["Open in IntelliJ IDEA
Import as Gradle project"] IDE --> DETEKT["Run Detekt
./gradlew detekt"] DETEKT --> TESTS["Run tests
./gradlew test"] TESTS --> READY["Ready to contribute!"]

style CLONE fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
style JDK fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
style REDIS fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
style BUILD fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
style IDE fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
style DETEKT fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
style TESTS fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
style READY fill:#2d333b,stroke:#6d5dfc,color:#e6edf3

sites:

- **JDK 17** — required by the JVM toolchain configuration in `build.gradle.kts`
- **Redis** — required for integration tests
- **IntelliJ IDEA** — recommended (Kotlin support is first-class)

### Running Tests

```bash
# Run all tests across all modules
./gradlew test

# Run tests for a specific module
./gradlew :cosky-core:test
./gradlew :cosky-config:test
./gradlew :cosky-discovery:test

# Run a single test class
./gradlew :cosky-config:test --tests "me.ahoo.cosky.config.redis.RedisConfigServiceTest"

# Run tests with verbose output
./gradlew :cosky-config:test --info

All test classes use JUnit 5 and the me.ahoo.test:fluent-assert-core library for assertions. When writing tests, always use:

kotlin

import me.ahoo.test.asserts.assert

// Correct:
actual.assert().isEqualTo(expected)

// Do NOT use AssertJ's assertThat() — it is verbose and not null-safe in Kotlin

Code Style

CoSky uses Detekt for static analysis with auto-correct enabled:

bash

# Check for style violations
./gradlew detekt

# Detekt auto-correct is enabled by default in build.gradle.kts
# It will fix formatting issues automatically during build

Key style rules:

All source files must have an Apache 2.0 license header
Compiler flags: -Xjsr305=strict, -Xjvm-default=all-compatibility
All core APIs return Mono or Flux (Project Reactor)
All Redis mutations go through Lua scripts — never use multi-command sequences

PR Process

Fork the repository (or create a branch if you have push access)
Create a feature branch from main: git checkout -b feature/my-feature
Write tests first — all new features and bug fixes must have tests
Run the full build: ./gradlew build detekt
Commit with a descriptive message
Open a Pull Request against main
CI will run integration tests, benchmarks, code coverage, and Detekt checks

What to Contribute

Good first issues:

New load balancer strategies — implement the LoadBalancer interface
Dashboard improvements — the dashboard/ directory contains a React 19 frontend
Documentation — the wiki/ directory contains the VitePress documentation site
Test coverage — look for uncovered code paths in the Jacoco reports

Areas requiring careful review (discuss before changing):

Lua scripts — they enforce critical consistency invariants
Redis key schema — changes break backward compatibility
Consistency layer wrappers — they are the performance foundation

Key Files Reference

The table below lists the most important source files. Bookmark these — you will reference them frequently.

File	Purpose
cosky-core/.../CoSky.kt	Brand constants and key separator
cosky-core/.../Namespaced.kt	Namespace defaults and system namespace
cosky-core/.../RedisKeys.kt	Hash tag wrapping for Redis Cluster
cosky-config/.../ConfigKeyGenerator.kt	Config Redis key patterns
cosky-config/.../ConfigService.kt	Config service interface
cosky-config/.../RedisConfigService.kt	Config Redis implementation
cosky-config/.../RedisConsistencyConfigService.kt	Config consistency wrapper
cosky-config/src/main/resources/config_set.lua	Atomic config set + version + history
cosky-discovery/.../DiscoveryKeyGenerator.kt	Discovery Redis key patterns
cosky-discovery/.../ServiceRegistry.kt	Registry interface
cosky-discovery/.../ServiceDiscovery.kt	Discovery interface
cosky-discovery/.../ConsistencyRedisServiceDiscovery.kt	Discovery consistency wrapper
cosky-discovery/.../RedisServiceRegistry.kt	Registry Redis implementation
cosky-discovery/src/main/resources/registry_register.lua	Atomic instance registration
cosky-discovery/src/main/resources/registry_renew.lua	Heartbeat renewal with throttled PubSub
cosky-rest-api/.../ServiceController.kt	Service REST endpoints
build.gradle.kts	Root build configuration
settings.gradle.kts	Module declarations

Contributor Workflow Diagram

mermaid

flowchart LR
    subgraph "Local Development"
        BRANCH["Create branch"] --> CODE["Write code + tests"]
        CODE --> DETEKT_LOCAL["Run detekt"]
        DETEKT_local --> BUILD_LOCAL["Run build"]
        BUILD_LOCAL --> COMMIT["Commit"]
    end

    subgraph "Pull Request"
        COMMIT --> PUSH["Push to GitHub"]
        PUSH --> PR["Open PR"]
    end

    subgraph "CI Pipeline"
        PR --> CI_TEST["Integration tests"]
        CI_TEST --> CI_DETEKT["Detekt check"]
        CI_DETEKT --> CI_COVERAGE["Code coverage"]
        CI_COVERAGE --> CI_BENCH["JMH benchmarks"]
    end

    CI_BENCH --> REVIEW["Code review"]
    REVIEW --> MERGE["Merge to main"]

    style BRANCH fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style CODE fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style DETEKT_local fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style BUILD_LOCAL fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style COMMIT fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style PUSH fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style PR fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style CI_TEST fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style CI_DETEKT fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style CI_COVERAGE fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style CI_BENCH fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style REVIEW fill:#2d333b,stroke:#6d5dfc,color:#e6edf3
    style MERGE fill:#2d333b,stroke:#6d5dfc,color:#e6edf3

Contributor Onboarding Guide ​

Part I — Foundations ​

What is CoSky? ​

Tech Stack ​

Building the Project ​

Redis Requirement ​

Part II — Architecture and Domain ​

Module Structure ​

The Consistency Pattern: Local Cache + PubSub Invalidation ​

Redis Key Schema ​

Lua Scripts for Atomic Operations ​

The Event Model ​

Part III — Contributing ​

Development Environment Setup ​

Code Style ​

PR Process ​

What to Contribute ​

Key Files Reference ​

Contributor Workflow Diagram ​

Contributor Onboarding Guide

Part I — Foundations

What is CoSky?

Tech Stack

Building the Project

Redis Requirement

Part II — Architecture and Domain

Module Structure

The Consistency Pattern: Local Cache + PubSub Invalidation

Redis Key Schema

Lua Scripts for Atomic Operations

The Event Model

Part III — Contributing

Development Environment Setup

Code Style

PR Process

What to Contribute

Key Files Reference

Contributor Workflow Diagram