Experimental Refactoring with Go

Refactoring is essential to the software lifecycle. Can we make it safe enough to be a part of every company's CD workflow? In this talk attendees will learn how to: utilise multi-step deploys; tame feature flags; run multiple code paths concurrently in production without influencing users.

Transcript

1. Experimental Refactoring
   

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2. FIND ME
   github.com/jelmersnoeck
   twitter.com/jelmersnoeck
   Jelmer Snoeck
   ABOUT ME
   - Tech Lead at manifold.co
   - Kubernetes
   - Terraform
   - Gopher since 2013
   - Kubelist Contributor
   

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3. $ tree
   - What and why?
   - Techniques & Tools
   - Zero Downtime Refactoring
   - Experimental Refactoring
   

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4. Photo by Dan Gold on Unsplash
   Refactoring
   

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5. Code refactoring is the process of
   restructuring existing computer code
   without changing its external behavior.
   Wikipedia
   

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6. Refactoring is a controlled technique for
   improving the design of an existing code
   base.
   Martin Fowler
   

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7. Refactoring is changing things, deploying
   it and hoping it didn’t break anything
   else.
   Most Developers
   

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8. Photo by Emily Morter on Unsplash
   Why
   

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9. Photo by Alfons Morales on Unsplash
   Readability
   

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10. Photo by Anton Darius on Unsplash
    Code smells
    

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11. Code smells
    - Duplication
    - Feature envy
    - Large methods
    - Dead code
    - …
    

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12. Photo by Glen Carrie on Unsplash
    Bugs
    

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13. Product Changes
    Photo by Chris Lawton on Unsplash
    Product changes
    

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14. Product changes
    - New features
    - Modify existing features
    - …
    

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15. Photo by Nainoa Shizuru on Unsplash
    Performance + scalability
    

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16. Performance
    - Change of underlying package
    - Change of underlying algorithm
    - …
    

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17. Scalability
    - Userbase growth (100 users to 100m users)
    - Team growth (10 developers to 500 developers)
    - …
    

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18. Photo by Anoir Chafik on Unsplash
    

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19. Techniques
    Photo by Uriel Soberanes on Unsplash
    

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20. Techniques
    - Interface Abstraction
    - Type Aliasing (Go 1.9+)
    - Nil Objects
    - …
    

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21. Interfaces
    (Abstraction)
    Photo by Rene Böhmer on Unsplash
    

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27. Photo by Kipras Štreimikis on Unsplash
    Type Aliasing
    

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33. Photo by Aaron Burden on Unsplash
    Nil Objects
    

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41. Photo by Philip Swinburn on Unsplash
    Tools
    

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42. Detection Tools
    - CodeCov
    - Linting
    - …
    

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43. CodeCov
    Photo by Samuel Zeller on Unsplash
    

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49. Linting
    Photo by Terri Bleeker on Unsplash
    

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53. Refactoring Tools
    - Tests
    - Security that it still works
    - Gotests
    - Benchmarks
    - go test -bench=.
    - IDE
    - Extract methods
    - Find duplication easily
    

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54. gotests
    Photo by rawpixel on Unsplash
    

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59. go test -bench=.
    Photo by Ashley Baxter on Unsplash
    

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64. Photo by Mark Hessling on Unsplash
    

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65. Photo by Jyotirmoy Gupta on Unsplash
    

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66. Photo by Marcus Benedix on Unsplash
    

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67. Zero
    Downtime
    Refactoring
    Photo by Masaaki Komori on Unsplash
    

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68. Multi Step Changes
    Photo by Jake Hills on Unsplash
    

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76. Photo by Jane Carmona on Unsplash
    Feature Flags
    

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78. Why use Feature Toggles?
    - Early Access to Features
    - Incremental roll outs to test hypothesis
    - Calendar Events (Mother’s day, Launches, …)
    - …
    

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82. Metrics
    Photo by Carlos Muza on Unsplash
    

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84. Experimental Refactoring
    Photo by chuttersnap on Unsplash
    

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87. Photo by chuttersnap on Unsplash
    

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102. @jelmersnoeck
     manifold.co
     Thanks!
     

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103. Reading list
     - https://speakerdeck.com/campoy/understanding-nil
     - https://talks.golang.org/2016/refactor.article
     - https://dave.cheney.net/2013/06/30/how-to-write-benchmarks-in-go
     - https://github.com/cweill/gotests
     - https://github.com/github/scientist
     - https://github.com/jelmersnoeck/experiment
     - http://featureflags.io/
     - https://github.com/launchdarkly/go-client
     - https://github.com/checkr/flagr
     

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