A short talk on Elixir adoption in RabbitMQ, a multi-protocol open source messaging broker: the motivation, how it compares to Erlang for our needs, and what we've learnt about 1 year into it.

1. Adopting Elixir in a 10
Year Old Codebase
Michael Klishin, Pivotal Software Inc.

2. Who am I?

3. Who am I?
• Yada Yada Yada Staff Software Engineer at
Pivotal

4. Who am I?
• Yada Yada Yada Staff Software Engineer at
Pivotal
• RabbitMQ core team member

6. About this talk

7. About this talk
• This is an experience report

8. About this talk
• This is an experience report
• Some arguments may be subjective or team-
specific, YMMV

10. What's the Project?

11. What's the Project?
• RabbitMQ

12. What's the Project?
• RabbitMQ
• Started in 2006, before Elixir (Rebar, Lager,
Cowboy, Ranch, dinosaurs, …) existed

13. What's the Project?
• RabbitMQ
• Started in 2006, before Elixir (Rebar, Lager,
Cowboy, Ranch, dinosaurs, …) existed
• Lots of wheels invented, some are not very round

14. What's the Project?
• RabbitMQ
• Started in 2006, before Elixir (Rebar, Lager,
Cowboy, Ranch, dinosaurs, …) existed
• Lots of wheels invented, some are not very round
• New team with a new perspective on things in
the last ~ 2 years

15. What's the Project?
• 7 engineers + ~ 3 active contributors, all kinds of
backgrounds (Erlang, Java, C#/F#, C, …)

16. What's the Project?
• 7 engineers + ~ 3 active contributors, all kinds of
backgrounds (Erlang, Java, C#/F#, C, …)
• Includes several client libraries we maintain, lots
of plugins

17. What's the Project?
• 7 engineers + ~ 3 active contributors, all kinds of
backgrounds (Erlang, Java, C#/F#, C, …)
• Includes several client libraries we maintain, lots
of plugins
• There are projects at Pivotal that depend on what
we do

19. How do we use Elixir?

20. How do we use Elixir?
• All core CLI tools as of 3.7.0

21. How do we use Elixir?
• All core CLI tools as of 3.7.0
• Experimental plugins

22. How do we use Elixir?
• All core CLI tools as of 3.7.0
• Experimental plugins
• Future tools and plugins

23. How do we use Elixir?
• All core CLI tools as of 3.7.0
• Experimental plugins
• Future tools and plugins
• Recruitment honey pot (discovered accidentally)
😂

25. Why Elixir?

26. Why new CLI tools?
• Homegrown CLI option parser is meh

27. Why new CLI tools?
• Homegrown CLI option parser is meh
• CLI tools are too tied to the server, non-
extensible

28. Why new CLI tools?
• Homegrown CLI option parser is meh
• CLI tools are too tied to the server, non-
extensible
• A project-within-a-project

29. Why Elixir?

30. Why Elixir?
• Elixir's OptionParser seems to be inspired by
Ruby & Python ones

31. Why Elixir?
• Elixir's OptionParser seems to be inspired by
Ruby & Python ones
• Associative data structures in Elixir are a solid
improvement over Erlang's

32. Why Elixir?
• Elixir's OptionParser seems to be inspired by
Ruby & Python ones
• Associative data structures in Elixir are a solid
improvement over Erlang's
• Interoperability with Erlang makes it very easy to
try

33. Why Elixir?
• Elixir's OptionParser seems to be inspired by Ruby
& Python ones
• Associative data structures in Elixir are a solid
improvement over Erlang's
• Interoperability with Erlang makes it very easy to
try
• We had over 50 repos already, one more wouldn't
hurt

34. Why Elixir
• Unicode is not an afterthought

35. Why Elixir
• Unicode is not an afterthought
• More approachable to other teams

36. Why Elixir
• Unicode is not an afterthought
• More approachable to other teams
• A very low risk endeavour for products already
running on BEAM

38. How did it go?

39. How did it go?
• Next feature release will include the new CLI
tools in Elixir

40. How did it go?
• Next feature release will include the new CLI
tools in Elixir
• Close to 70 commands, ~ 750 tests, ~ 8K lines of
code

41. How did it go?
• Next feature release will include the new CLI
tools in Elixir
• Close to 70 commands, ~ 750 tests, ~ 8K lines of
code
• New features: extensibility from plugins, result
set streaming for listing commands, much better
argument validation, …

42. How did it go?
• Next feature release will include the new CLI tools
in Elixir
• Close to 70 commands, ~ 750 tests, ~ 8K lines of
code
• New features: extensibility from plugins, result set
streaming for listing commands, much better
argument validation, …
• Well received by other teams at Pivotal 👍

43. How did it go?

44. How did it go?
• Quickly adopted by folks without prior Elixir and
virtually no Erlang experience 👍

45. How did it go?
• Quickly adopted by folks without prior Elixir and
virtually no Erlang experience 👍
• Very decent standard library 👍

46. How did it go?
• Quickly adopted by folks without prior Elixir and
virtually no Erlang experience 👍
• Very decent standard library 👍
• ExUnit is up there with Spock, RSpec 👍

47. How did it go?
• Quickly adopted by folks without prior Elixir and
virtually no Erlang experience 👍
• Very decent standard library 👍
• ExUnit is up there with Spock, RSpec 👍
• Error messages in Elixir are more sensible 👍

48. How did it go?
• Tooling and dependency management from this
century 👍

49. How did it go?
• Tooling and dependency management from this
century 👍
• Upgrading between Elixir versions was very easy
😍

50. How did it go?
• Tooling and dependency management from this
century 👍
• Upgrading between Elixir versions was very easy
😍
• Some Elixir libraries are better than their Erlang
alternatives 🐼

52. How did it go?

53. How did it go?
• Integration with erlang.mk 😣

54. How did it go?
• Integration with erlang.mk 😣
• Confusing to those spending too much time with
Erlang 😕

55. How did it go?
• Integration with erlang.mk 😣
• Confusing to those spending too much time with
Erlang 😕
• Elixir/Erlang data type mismatches 😣

56. How did it go?
• Integration with erlang.mk 😣
• Confusing to those spending too much time with
Erlang 😕
• Elixir/Erlang data type mismatches 😣
• Some Elixir libraries are a one man show 🤞

57. How did it go?
• Integration with erlang.mk 😣
• Confusing to those spending too much time with
Erlang 😕
• Elixir/Erlang data type mismatches 😣
• Some Elixir libraries are a one man show 🤞
• Elixir skeptics in the community 🤞

59. Cool Elixir features our code
uses

60. Cool Elixir features our code
uses
• Functions

61. Cool Elixir features our code
uses
• Functions
• Modules

62. Cool Elixir features our code
uses
• Functions
• Modules
• Standard library

63. Cool Elixir features our code
uses
• Functions
• Modules
• Standard library
• Streams

64. Cool Elixir features our code
uses
• Functions
• Modules
• Standard library
• Streams
• Macros? Nope.

65. Cool Elixir features our code
uses
• Functions
• Modules
• Standard library
• Streams
• Macros? Nope.
• Agents? Nope.

66. Cool Elixir features our code
uses
• Tasks? No.

67. Cool Elixir features our code
uses
• Tasks? No.
• Sweet frameworks? Nooooooooo.

69. Could we build the same
thing in Erlang?

70. Could we build the same
thing in Erlang?
• Technically, absolutely

71. Could we build the same
thing in Erlang?
• Technically, absolutely
• In terms of perception by potential contributors,
probably not

73. Where do we go from here?

74. Where do we go from here?
• Moar Elixir

75. Where do we go from here?
• Moar Elixir
• Moar Erlang

76. Where do we go from here?
• Moar Elixir
• Moar Erlang
• Fewer unnecessarily reinvented wheels 🙏

78. @michaelklishin

79. Questions?