什么是 trunk-based development，它如何支持 CI/CD？

Question

Accepted Answer

**Trunk-based development** 是一种分支策略，开发人员**频繁地将小的变更集成到单一主分支（trunk）中**，使用生命周期极短的分支（或直接提交）。它与高性能 CI/CD 紧密相关，因为它最大化了持续集成。

## Trunk-based development 是什么

```text
Developers commit small, frequent changes to a SINGLE shared branch (trunk/main):
  → very SHORT-LIVED branches (merged within hours or a day) — or commit directly
  → integrate continuously (multiple times a day) into trunk
  → trunk is kept always RELEASABLE (working, deployable)
→ vs long-lived feature branches that diverge for days/weeks before merging.
```

## 它为什么很好地支持 CI/CD

```text
✓ MAXIMIZES continuous INTEGRATION — frequent small merges = the essence of CI
  (catch integration issues immediately; tiny, easy-to-resolve conflicts)
✓ AVOIDS "merge hell" — no long-lived branches diverging → no big painful merges
✓ Small changes = lower risk, easier review, faster feedback
✓ Keeps trunk always deployable → enables continuous DELIVERY/deployment
→ Research (DORA) links trunk-based development to high delivery performance.
```

## 处理未完成的工作

```text
How to commit to trunk frequently when features aren't done?
  ✓ FEATURE FLAGS → merge incomplete features hidden behind off flags (don't break trunk)
  ✓ Break work into small, independently-mergeable, non-breaking pieces
  ✓ Branch by ABSTRACTION → introduce changes incrementally behind abstractions
→ The discipline: integrate small, keep trunk working, hide incomplete work.
```

## Trunk-based 与 feature-branch（Git Flow）对比

```text
TRUNK-BASED → short-lived branches, frequent integration, continuous delivery,
  feature flags — favored for high-velocity CI/CD
GIT FLOW (long-lived branches) → more structured, release-oriented, but longer
  divergence and bigger merges → less continuous
→ Trunk-based is generally preferred for true CI/CD; Git Flow for scheduled releases.
```

## 为什么这很重要

理解 trunk-based development 是很有价值的高级知识，因为它**与高性能 CI/CD 紧密相关**，代表了一种重要的分支策略，因此对于理解有效的交付实践非常有用。

核心思想——开发人员使用生命周期极短的分支（而不是长期存在的 feature 分支，这些分支可能会发散数天或数周）**频繁地将小的变更集成到单一 trunk 中**——直接**最大化了持续集成**，这是 CI 的本质：频繁的小型合并能够立即发现集成问题，并产生很小、容易解决的冲突，**避免了长期发散分支的