Copyright © 2015 SolutionsIQ Inc. All rights reserved. Branching for CD? Think again ! Devesh Chanchlani

Self Introduction Passionate Programmer Technical Agile Coach with SolutionsIQ Coach teams to embrace, scale and sustain XP practices Belong to Pune Branching for CD? Think Again! – Devesh Chanchlani 2

Project Background  Worked as an Technical Coach with a global e-payments company.  Multiple feature teams, contributing simultaneously in a release.  Each release would support numerous regions/countries.  Features would need to maintain compatibility across many vendor solutions.  Made a released once an year  And now we decided to go LEAN and deliver continuously … Branching for CD? Think Again! – Devesh Chanchlani 3

4 When we started making FREQUENT releases …

Branching for CD? Think Again! – Devesh Chanchlani 5 Mainline Feature 1 Feature 2 Feature 3 Feature 4 RnRn R n+1 R n+2 When we started making Frequent Releases

Branching for CD? Think Again! – Devesh Chanchlani 6 Then we decided to deliver features INCREMENTALLY …

Branching for CD? Think Again! – Devesh Chanchlani 7 R1 Code-freeze R1 R2 Code-freeze R2 Development for R2 (12 weeks) Stabilizing R1 (4 weeks) Integration Feature 1 Feature 2 Feature 3 Feature 4 Stabilizing R2

Challenges observed  Merge-hells on integration branch before code-freeze (Processing)  Release stabilization phase being a drag (Inventory, Waiting)  Merges and stabilization leading to several code-hacks (Defects)  Merge-hells on feature branches after each release (Processing)  Even 100% automation won’t solve our problem 8 Branching for CD? Think Again! – Devesh Chanchlani

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On Retrospection … 10 Code-reuse & Refactoring becoming difficult No real Continuous Integration happening Isolated Feature teams

11 “Feature branching is a poor man's modular architecture, instead of building systems with the ability to easy swap in and out features at runtime / deploytime they couple themselves to the source control providing this mechanism through manual merging.” Dan Bodart Branching for CD? Think Again! – Devesh Chanchlani

Trunk Based Development (TBD) Branching for CD? Think Again! – Devesh Chanchlani 12

What it means …  All developers commit to a single branch, called trunk, making frequent check-ins.  Branches are created only for Release purpose.  Regular developers don’t commit to a release branch.  Release branches are never merged back to trunk.  Release branches are short-lived, frequently being replaced by other release branches. 13 Branching for CD? Think Again! – Devesh Chanchlani

14 Exploring Trunk Based Development Branching for CD? Think Again! – Devesh Chanchlani

15 Our BIGGEST Problem - Imagine you are releasing into production every two weeks, but need to build a feature that's going to take three months to complete. Branching for CD? Think Again! – Devesh Chanchlani

Feature Toggles 16 Courtesy: Spotify Labs / Henrik Kniberg Branching for CD? Think Again! – Devesh Chanchlani

Feature Toggle implies … 17  A configuration file defined a bunch of toggles for various pending features.  These toggles were mostly applied at UIs, from where interaction with the features began.  For features with no UI, the toggle would be in the app code.  using techniques like polymorphic substitution and dependency injection  Feature toggles were removed once the feature was complete.  Pipelines for different permutations of toggles for releases were setup.  If either of the build failed, it implied a bad commit. Branching for CD? Think Again! – Devesh Chanchlani

Feature Toggle types 18 1.Release – partial features, temporary 2.Business – certain class of users/regions, permanent (already existed) 3.Runtime – easier rollbacks, run tests with various configurations of features 4.Build – new feature codebase is not compiled Branching for CD? Think Again! – Devesh Chanchlani

19 Another Problem - Phasing out old implementations Branching for CD? Think Again! – Devesh Chanchlani

Branch by Abstraction 20 Consumer Component to be replaced STEP 1 Consumer Component to be replaced Abstraction Layer STEP 2 Consumer Old Component Abstraction Layer New Component STEP 3 Consumer Old Component Abstraction Layer New Component STEP 4 Branching for CD? Think Again! – Devesh Chanchlani

References  Paul Hammant -  Martin Fowler -  Carlos Lopes - Multiple projects, different goals, one thing in common: the codebase!  Henrik Kniberg – Engineering at Spotify  Chuck Rossi – The Facebook Release Process  Thanks to for comic characterswww.bitstrips.com 21 Branching for CD? Think Again! – Devesh Chanchlani

Our Customers 22 Branching for CD? Think Again! – Devesh Chanchlani

23 Thank you! solutionsiq.com Branching for CD? Think Again! – Devesh Chanchlani