Continuous Integration. Johannes Seitz

Transcription

1 Continuous Integration Johannes Seitz

2 What is Continuous Integration? That Jenkins job may be necessary, but not sufficient.

3 Ways of working in a team Integrating often Integrating in a Big Bang All changes integrated Commits Branches

4 Integrating in a Big Bang e. G. Long-lived feature branching, Some Implementations of Git Flow Pros: Cherry-picking features for release is easy Individual developers keep focussed on their branh Cons: Branch handling complexity Merges can get very complex Uncalculable Stabilisation phases Refactoring may make you unpopular

5 If it hurts, do it more often!

6 Integrating often e. G. Trunk-Based Development, Short lived (1-3 days) feature branching Pros: Merge conflicts are usually small Refactorings are easier Little to no branching overhead There is no chaotic integration phase Features don t rot in abandoned branches Enables continuous delivery Cons: Cherry-picking features for release is harder Individual team members may feel less productive Stories need to be small enough

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8 The controversy Taste everything [all advice] but only swallow what tastes right for you. Virginia Satir, the Mother of Systemic Family Therapy

9 Techniques for a more frequent integration

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11 Big Refactorings Continuously integrated

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13 Don t rip out the old code (yet)!

14 Branch by abstraction

15 Branch by abstraction

16 Branch by abstraction

17 Branch by abstraction

18 Branch by abstraction Pros Compare old vs new in Prod Integrating early and often Refactorings en passant or [Obsolete] Cons Should be used sparsely Works best with whole team approaches

19 Baby steps

20 Unfinished Features Continuously integrated

21 Feature toggles (Changes)

22 Feature toggles (New features) UI Domain DB

23 Feature toggles Pros: Allows canary releases of features Features are integrated all the time Product is always shippable Unfinishedfeatures can easily be tested Cons: Toggles become a form of tech debt unless removed Painful to do if your architecture is a nonmodular mess

24 DB schema changes Continuously integrated

25 Schema versioning Image Source:

26 Schema migrations

27 Schema versioning & migrations Pros: Schemas are versioned Everyone can change the Schema incrementally Schema is in version control Schema is documented Cons: Migrations bear a risk Your DBA may object Adding migrations can cause race conditions that need manual handling

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29 Library Changes Continuously integrated

30 Version pinning

31 Upgrade pains: Github In total the project took a year and a half to upgrade from Rails 3.2 to Rails 5.2 Upgrading Rails on an application as large and as trafficked as GitHub is no small task Lessons learned: Upgrade early and upgrade often. Source:

32 Version Pinning Pros: Dependency changes don t break your build Cons: You are missing out on features You are missing out on bug fixes Security holes creep in The inevitable update to the latest version will be VERY panful

33 Canary builds

34 Canary Builds Pros: Feedback about integration pains ahead Encourages continuous integration without breaking the build Great for security patches Cons: Two pipelines Works best with comprehensive test suites

35 Service Changes Continuously integrated

36 Consumer-Driven Contracts Consumer Service Provider Consumer

37 Consumer-Driven Contracts Source:

38 Consumer-Driven Contracts Consumer Service Provider Consumer

39 Consumer-Driven Contracts Pros: Producers can tell when they break compatibility Producers can tell which consumers will break Cons: Consumers and producers of services need to collaborate APIs need to expose (some) of their state for good contract tests

40 Thank you for your attention! Johannes Seitz, Blog: printhelloworld.de,

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42 Bonus Section!

43 Service test doubles Continuously tested

44 Integration Contract Tests Image Source:

45 Shared code Continuously integrated

46 Monorepositories Können gut benutzt werden um Abhängigkeiten zwischen Systemen synchron zu halten.

47 Build breaking commits Rejected before they reach the repo

48 Pre-tested commits