遗留系统现代化改造工具：安全迁移、绞杀者模式、特性测试指南

legacy-modernizer by jeffallan/claude-skills

801 周安装量

7,300 GitHub Stars

GitHub

安装命令

npx skills add https://github.com/jeffallan/claude-skills --skill legacy-modernizer

开发开发运维测试

🇨🇳中文介绍

遗留系统现代化改造工具

核心工作流程

评估系统 — 分析代码库、依赖项、风险和业务约束。在继续之前生成依赖关系图和风险登记册。
- 验证检查点: 在进入第 2 步之前，确认所有外部集成和数据契约都已记录在案。
规划迁移 — 设计一个增量路线图，每个阶段都有明确的回滚策略。参考 references/system-assessment.md 获取代码分析模板。
- 验证检查点: 确认每个阶段都定义了回滚触发条件和负责人。
构建安全网 — 在接触生产代码之前，创建特性测试和监控。目标是对现有行为实现 80% 以上的覆盖率。
- 验证检查点: 运行特性测试套件，并确认其在未修改的遗留系统上通过（绿色）后再继续。
增量迁移 — 结合特性标志应用绞杀者模式。通过外观层路由流量；逐步转移负载。
- 验证检查点: 在每次流量增量（例如，5% → 25% → 50% → 100%）后，验证错误率和延迟指标是否保持在基线阈值内。
验证与迭代 — 运行完整的测试套件，审查监控仪表板，并在废弃遗留代码之前确认业务行为得以保留。
- 验证检查点: 在移除遗留路径之前，新代码必须在 100% 流量下至少稳定运行一个发布周期。

参考指南

根据上下文加载详细指导：

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绞杀者模式外观层 (Python)

# facade.py — routes requests to legacy or new service based on a feature flag
import os
from legacy_service import LegacyOrderService
from new_service import NewOrderService

class OrderServiceFacade:
    def __init__(self):
        self._legacy = LegacyOrderService()
        self._new = NewOrderService()

    def get_order(self, order_id: str):
        if os.getenv("USE_NEW_ORDER_SERVICE", "false").lower() == "true":
            return self._new.fetch(order_id)
        return self._legacy.get(order_id)

特性标志包装器

# feature_flags.py — thin wrapper around an environment or config-based flag store
import os

def flag_enabled(flag_name: str, default: bool = False) -> bool:
    """Check whether a migration feature flag is active."""
    return os.getenv(flag_name, str(default)).lower() == "true"

# Usage
if flag_enabled("USE_NEW_PAYMENT_GATEWAY"):
    result = new_gateway.charge(order)
else:
    result = legacy_gateway.charge(order)

特性测试模板 (pytest)

# test_characterization_orders.py
# Captures existing legacy behavior as a golden-master safety net.
import pytest
from legacy_service import LegacyOrderService

service = LegacyOrderService()

@pytest.mark.parametrize("order_id,expected_status", [
    ("ORD-001", "SHIPPED"),
    ("ORD-002", "PENDING"),
    ("ORD-003", "CANCELLED"),
])
def test_order_status_golden_master(order_id, expected_status):
    """Fail loudly if legacy behavior changes unexpectedly."""
    result = service.get(order_id)
    assert result["status"] == expected_status, (
        f"Characterization broken for {order_id}: "
        f"expected {expected_status}, got {result['status']}"
    )

在所有迁移过程中保持零生产中断
在重构之前创建全面的测试覆盖率（目标 80% 以上）
对所有增量发布使用特性标志
实施监控和回滚程序
记录所有迁移决策及其理由
保留现有的业务逻辑和行为
透明地沟通进展和风险

大规模重写或替换（大爆炸式）
在变更前跳过测试遗留行为
部署不具备回滚能力的版本
破坏现有的集成或 API
在新代码中忽视技术债务
未经适当验证就仓促迁移
在新代码被验证稳定前移除遗留代码

实施现代化改造时，请提供：

评估摘要（风险、依赖项、方法）
迁移计划（阶段、回滚策略、指标）
实现代码（外观层、适配器、新服务）
测试覆盖率（特性测试、集成测试、端到端测试）
监控设置（指标、告警、仪表板）

绞杀者模式、抽象分支、特性测试、增量迁移、特性标志、金丝雀部署、API 版本控制、数据库重构、微服务提取、技术债务削减、零停机部署

🇺🇸English

Legacy Modernizer

Core Workflow

Assess system — Analyze codebase, dependencies, risks, and business constraints. Produce a dependency map and risk register before proceeding.
- Validation checkpoint: Confirm all external integrations and data contracts are documented before moving to step 2.
Plan migration — Design an incremental roadmap with explicit rollback strategies per phase. Reference references/system-assessment.md for code analysis templates.
- Validation checkpoint: Confirm each phase has a defined rollback trigger and owner.
Build safety net — Create characterization tests and monitoring before touching production code. Target 80%+ coverage of existing behavior.
- Validation checkpoint: Run the characterization test suite and confirm it passes green on the unmodified legacy system before proceeding.
Migrate incrementally — Apply strangler fig pattern with feature flags. Route traffic via a facade; shift load gradually.
- Validation checkpoint: Verify error rates and latency metrics remain within baseline thresholds after each traffic increment (e.g., 5% → 25% → 50% → 100%).
Validate & iterate — Run full test suite, review monitoring dashboards, and confirm business behavior is preserved before retiring legacy code.
- Validation checkpoint: New code must be proven stable at 100% traffic for at least one release cycle before legacy path is removed.

Reference Guide

Load detailed guidance based on context:

Topic	Reference	Load When
Strangler Fig	`references/strangler-fig-pattern.md`	Incremental replacement, facade layer, routing
Refactoring	`references/refactoring-patterns.md`	Extract service, branch by abstraction, adapters
Migration	`references/migration-strategies.md`	Database, UI, API, framework migrations
Testing	`references/legacy-testing.md`	Characterization tests, golden master, approval
Assessment	`references/system-assessment.md`

Code Examples

Strangler Fig Facade (Python)

# facade.py — routes requests to legacy or new service based on a feature flag
import os
from legacy_service import LegacyOrderService
from new_service import NewOrderService

class OrderServiceFacade:
    def __init__(self):
        self._legacy = LegacyOrderService()
        self._new = NewOrderService()

    def get_order(self, order_id: str):
        if os.getenv("USE_NEW_ORDER_SERVICE", "false").lower() == "true":
            return self._new.fetch(order_id)
        return self._legacy.get(order_id)

Feature Flag Wrapper

# feature_flags.py — thin wrapper around an environment or config-based flag store
import os

def flag_enabled(flag_name: str, default: bool = False) -> bool:
    """Check whether a migration feature flag is active."""
    return os.getenv(flag_name, str(default)).lower() == "true"

# Usage
if flag_enabled("USE_NEW_PAYMENT_GATEWAY"):
    result = new_gateway.charge(order)
else:
    result = legacy_gateway.charge(order)

Characterization Test Template (pytest)

# test_characterization_orders.py
# Captures existing legacy behavior as a golden-master safety net.
import pytest
from legacy_service import LegacyOrderService

service = LegacyOrderService()

@pytest.mark.parametrize("order_id,expected_status", [
    ("ORD-001", "SHIPPED"),
    ("ORD-002", "PENDING"),
    ("ORD-003", "CANCELLED"),
])
def test_order_status_golden_master(order_id, expected_status):
    """Fail loudly if legacy behavior changes unexpectedly."""
    result = service.get(order_id)
    assert result["status"] == expected_status, (
        f"Characterization broken for {order_id}: "
        f"expected {expected_status}, got {result['status']}"
    )

Constraints

MUST DO

Maintain zero production disruption during all migrations
Create comprehensive test coverage before refactoring (target 80%+)
Use feature flags for all incremental rollouts
Implement monitoring and rollback procedures
Document all migration decisions and rationale
Preserve existing business logic and behavior
Communicate progress and risks transparently

MUST NOT DO

Big bang rewrites or replacements
Skip testing legacy behavior before changes
Deploy without rollback capability
Break existing integrations or APIs
Ignore technical debt in new code
Rush migrations without proper validation
Remove legacy code before new code is proven

Output Templates

When implementing modernization, provide:

Assessment summary (risks, dependencies, approach)
Migration plan (phases, rollback strategy, metrics)
Implementation code (facades, adapters, new services)
Test coverage (characterization, integration, e2e)
Monitoring setup (metrics, alerts, dashboards)

Knowledge Reference

Strangler fig pattern, branch by abstraction, characterization testing, incremental migration, feature flags, canary deployments, API versioning, database refactoring, microservices extraction, technical debt reduction, zero-downtime deployment

Weekly Installs

787

Repository

jeffallan/claude-skills

GitHub Stars

7.2K

First Seen

Jan 20, 2026

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