Your Monolith, Elixir and You

Elixir is great, so clearly we'll all rewrite our applications in Elixir. Mostly, you can't and shouldn't do that. This presentation will show you another path. You’ll see how at Liefery, we started with small steps instead of rewriting everything. This allowed us to reap the benefits earlier and get comfortable before getting deeper into it. We’ll examine in detail the tactics we used to create two Elixir apps for new requirements, and how we integrated them with our existing Rails code base.

Transcript

2. functional
3. functional ErlangVM
4. functional ErlangVM Parallelism
5. Who wants to go and build a system in Elixir?
10. You shouldn’t
11. Elixir, Your Monolith and You Tobias Pfeiffer @PragTob pragtob.info
12. Your Monolith and You
14. Your Monolith now?
15. Your Monolith?
16. Tear it all down and rewrite it
18. Sooooon!
19. “We rewrote it all in Language x, now it’s 10 times faster and only 50% of the code!” Someone
20. “Language x, is 10 times faster and requires 50% of the code of language Y!” Someone Often implies...
21. What nobody tells you...
22. Business Value?
23. Sooooon!
24. Replace it step by step
25. We have a bedroom, for the bathroom please check out legacy!
26. Terraform allows you to incrementally transform an older API into one powered by Phoenix - one endpoint at a time. poteto/terraform
27. Terraform allows you to incrementally transform an older API into one powered by Phoenix - one endpoint at a time. poteto/terraform Not the Infrastructure As Code
28. defmodule MyApp.Terraformers.Foo do alias MyApp.Clients.Foo use Plug.Router plug :match plug :dispatch get "/v1/hello-world", do: send_resp(conn, 200, "Hi") get _ do res = Foo.get!(conn) send_response({:ok, conn, res}) end end poteto/terraform
29. Replace a critical component
30. Damn our heater always breaks down when it’s cold!
31. Check out our sweet new heating system!
32. Write a new component
33. Check it out we built a brand new high tech entertainment facility!
34. Write a new component Obvious in microservices
35. “Is the technology I’m choosing the right fit for the problem I’m trying to solve?” Everyone, hopefully
36. Reasonably separate and limited problem
37. Requirement that poses a problem for the current stack
38. Spark of Enthusiasm
39. Courier Tracking
40. Courier Tracking
41. Courier Tracking
42. Courier Tracking Websockets
43. Courier Tracking Websockets Basic Knowledge
44. How to make them talk?
45. Monolith Frontend Courier DB
46. Monolith Tracking Frontend Courier DB DB
47. Connect them?
48. Monolith Tracking Frontend Courier DB DB
49. JSON Web Token
50. Header Payload Signature
51. { "role": "admin", "courier_ids": [1337, 55], "id": 42, "exp": 1520469475 }
52. Monolith Tracking Frontend Courier DB DB Shared Secret
53. Monolith Tracking Frontend Courier DB DB JWT JWT Shared Secret
54. Monolith Tracking Frontend Courier DB DB JWT JWT JWT Shared Secret JWT
55. def connect(%{"token" => token}, socket) do token |> JWT.verify_token |> respond_based_on_token_contents(socket) end Socket
56. def connect(%{"token" => token}, socket) do token |> JWT.verify_token |> respond_based_on_token_contents(socket) end Pattern Match
57. def connect(%{"token" => token}, socket) do token |> JWT.verify_token |> respond_based_on_token_contents(socket) end Pipe
58. defp login_user(%{"role" => role, ...}, socket) do {:ok, assign(socket, :user, %{role: role, ...})} end Socket
59. def join("courier:" <> courier_id, _, %{assigns: %{user: user}}) do if authorized?(courier_id, user) do # login else # unauthorizd end end Channel
60. defp authorized?("", _), do: false defp authorized?(courier_id, %{courier_ids: ids}) do Enum.member?(ids, String.to_integer(courier_id)) end defp authorized?(_, _), do: false Channel
61. defp authorized?("", _), do: false defp authorized?(courier_id, %{courier_ids: ids}) do Enum.member?(ids, String.to_integer(courier_id)) end defp authorized?(_, _), do: false Channel
62. defp authorized?("", _), do: false defp authorized?(courier_id, %{courier_ids: ids}) do Enum.member?(ids, String.to_integer(courier_id)) end defp authorized?(_, _), do: false Channel
63. defp authorized?("", _), do: false defp authorized?(courier_id, %{courier_ids: ids}) do Enum.member?(ids, String.to_integer(courier_id)) end defp authorized?(_, _), do: false Channel
64. defp authorized?("", _), do: false defp authorized?(courier_id, %{courier_ids: ids}) do Enum.member?(ids, String.to_integer(courier_id)) end defp authorized?(_, _), do: false Channel
65. Monolith Tracking Frontend Courier DB DB Locations Locations Most of the time
66. Monolith Tracking Frontend Courier DB DB Locations Locations Websocket
67. Monolith Tracking Frontend Courier DB DB Locations Locations HTTP REST
68. Fulfillment
69. Fulfillment CRUD
70. Fulfillment CRUD Experience
71. Monolith Fulfillment DB DB
72. Monolith Fulfillment DB DB Own UI
73. Monolith Fulfillment DB DB OAuth OAuth
74. Monolith Fulfillment DB DB /current_user Who?
75. Monolith Fulfillment DB DB Products
76. Monolith Fulfillment DB DB Order Valid? Order
77. Monolith Fulfillment DB DB Packaging Create
78. Monolith Fulfillment DB DB HTTP REST Create
79. Railway Oriented Programming
80. defmodule Fulfillment.OrderCreation do def create(params, customer, auth) do with {:ok, order} <- validate_order(params, customer), {:ok, order} <- validate_in_backend(order, auth), {:ok, order} <- Repo.insert(order) do {:ok, order} else {:error, changeset} -> {:error, changeset} end end end
81. defmodule Fulfillment.OrderCreation do def create(params, customer, auth) do with {:ok, order} <- validate_order(params, customer), {:ok, order} <- validate_in_backend(order, auth), {:ok, order} <- Repo.insert(order) do {:ok, order} else {:error, changeset} -> {:error, changeset} end end end “Success” Rail
82. defmodule Fulfillment.OrderCreation do def create(params, customer, auth) do with {:ok, order} <- validate_order(params, customer), {:ok, order} <- validate_in_backend(order, auth), {:ok, order} <- Repo.insert(order) do {:ok, order} else {:error, changeset} -> {:error, changeset} end end end “Error” Rail
83. defmodule Fulfillment.OrderCreation do def create(params, customer, auth) do with {:ok, order} <- validate_order(params, customer), {:ok, order} <- validate_in_backend(order, auth), {:ok, order} <- Repo.insert(order) do {:ok, order} else {:error, changeset} -> {:error, changeset} end end end Validate internally
84. defmodule Fulfillment.OrderCreation do def create(params, customer, auth) do with {:ok, order} <- validate_order(params, customer), {:ok, order} <- validate_in_backend(order, auth), {:ok, order} <- Repo.insert(order) do {:ok, order} else {:error, changeset} -> {:error, changeset} end end end Validate externally
85. defmodule Fulfillment.OrderCreation do def create(params, customer, auth) do with {:ok, order} <- validate_order(params, customer), {:ok, order} <- validate_in_backend(order, auth), {:ok, order} <- Repo.insert(order) do {:ok, order} else {:error, changeset} -> {:error, changeset} end end end Save
86. defmodule Fulfillment.OrderCreation do def create(params, customer, auth) do with {:ok, order} <- validate_order(params, customer), {:ok, order} <- validate_in_backend(order, auth), {:ok, order} <- Repo.insert(order) do {:ok, order} else {:error, changeset} -> {:error, changeset} end end end Done
87. No Kafka/ Message Queue/ GraphQL?
88. Be careful with new technologies!
89. Microservices!
90. Microservices! ”Macroapplications”
91. All challenges are clearly technical
92. All challenges are clearly technical
93. Stakeholders
94. Your team
95. First Major Version
96. Get the others on board
97. Workshops
98. To know it, you got to build it
100. Pair Adopter with Alchemist
101. Pair Adopter with Alchemist Alchemist doesn’t touch keyboard
102. Knowledge
103. Knowledge
104. “We are still using this like Rails – we should use GenServers!” Someone on your team
105. You don’t need to kill your Monolith, Complement it
106. Your Apps
107. Enjoy Using Elixir effectively to Help Your Company Tobias Pfeiffer @PragTob pragtob.info