Switch to use DeferredConfig (#343)

apps/admin_api/config/config.exs

@@ -9,12 +9,12 @@ use Mix.Config
 config :admin_api,
   namespace: AdminAPI,
   ecto_repos: [],
-  base_url: System.get_env("BASE_URL") || "http://localhost:4000",
-  sender_email: System.get_env("SENDER_EMAIL") || "admin@localhost"
+  base_url: {:system, "BASE_URL", "http://localhost:4000"},
+  sender_email: {:system, "SENDER_EMAIL", "admin@localhost"}
 
 # Configs for the endpoint
 config :admin_api, AdminAPI.Endpoint,
-  secret_key_base: System.get_env("SECRET_KEY_BASE"),
+  secret_key_base: {:system, "SECRET_KEY_BASE"},
   error_handler: AdminAPI.V1.ErrorHandler,
   render_errors: [
     view: AdminAPI.ErrorView,
@@ -39,46 +39,6 @@ config :admin_api, :generators, context_app: false
 # Configs for Bamboo emailing library
 config :admin_api, AdminAPI.Mailer, adapter: Bamboo.LocalAdapter
 
-# Config for CORSPlug
-#
-# CORS_ORIGINS may contain multiple comma-separated origins, therefore it needs
-# to be splitted and trimmed. But since `config.exs` evaluates the options
-# at compile time, it does not allow an assignment with anonymous functions,
-# waiting to be executed at runtime.
-#
-# Because of this the anonymous function is invoked right away through
-# `(fn -> ... end).()` in order for :origin to be assigned at compile time.
-config :cors_plug,
-  # Lowest common value of all browsers
-  max_age: System.get_env("CORS_MAX_AGE") || 600,
-  headers: [
-    "Authorization",
-    "Content-Type",
-    "Accept",
-    "Origin",
-    "User-Agent",
-    "DNT",
-    "Cache-Control",
-    "X-Mx-ReqToken",
-    "Keep-Alive",
-    "X-Requested-With",
-    "If-Modified-Since",
-    "X-CSRF-Token",
-    "OMGAdmin-Account-ID"
-  ],
-  methods: ["POST"],
-  origin:
-    (fn ->
-       case System.get_env("CORS_ORIGINS") do
-         # Disallow all origins if CORS_ORIGINS is not set
-         nil ->
-           []
-
-         origins ->
-           origins |> String.trim() |> String.split(~r{\s*,\s*})
-       end
-     end).()
-
 # Two configs need to be added to have a new EWallet Admin version:
 #
 # 1. `admin_api.api_versions`
@@ -104,7 +64,7 @@ config :mime, :types, %{
 
 # Configs for Sentry exception reporting
 config :sentry,
-  dsn: System.get_env("SENTRY_DSN"),
+  dsn: {:system, "SENTRY_DSN"},
   environment_name: Mix.env(),
   enable_source_code_context: true,
   root_source_code_path: File.cwd!(),

apps/admin_api/config/prod.exs

@@ -1,14 +1,14 @@
 use Mix.Config
 
-config :admin_panel, base_url: System.get_env("BASE_URL")
+config :admin_panel, base_url: {:system, "BASE_URL"}
 
 # Configs for Bamboo emailing library
 config :admin_api, AdminAPI.Mailer,
   adapter: Bamboo.SMTPAdapter,
-  server: System.get_env("SMTP_HOST"),
-  port: System.get_env("SMTP_PORT"),
-  username: System.get_env("SMTP_USER"),
-  password: System.get_env("SMTP_PASSWORD")
+  server: {:system, "SMTP_HOST"},
+  port: {:system, "SMTP_PORT"},
+  username: {:system, "SMTP_USER"},
+  password: {:system, "SMTP_PASSWORD"}
 
 config :admin_api, AdminAPI.V1.Endpoint,
   debug_errors: true,

apps/admin_api/lib/admin_api/application.ex

@@ -4,9 +4,12 @@ defmodule AdminAPI.Application do
   """
   use Application
   alias AdminAPI.Endpoint
+  alias AdminAPI.Config
 
   def start(_type, _args) do
     import Supervisor.Spec
+    DeferredConfig.populate(:admin_api)
+    Config.configure_cors_plug()
 
     # Define workers and child supervisors to be supervised
     children = [

apps/admin_api/lib/admin_api/config.ex

@@ -0,0 +1,39 @@
+defmodule AdminAPI.Config do
+  @moduledoc """
+  Provides a configuration function that are called during application startup.
+  """
+
+  @headers [
+    "Authorization",
+    "Content-Type",
+    "Accept",
+    "Origin",
+    "User-Agent",
+    "DNT",
+    "Cache-Control",
+    "X-Mx-ReqToken",
+    "Keep-Alive",
+    "X-Requested-With",
+    "If-Modified-Since",
+    "X-CSRF-Token",
+    "OMGAdmin-Account-ID"
+  ]
+
+  def configure_cors_plug do
+    max_age = System.get_env("CORS_MAX_AGE") || 600
+    cors_origin = System.get_env("CORS_ORIGIN")
+
+    Application.put_env(:cors_plug, :max_age, max_age)
+    Application.put_env(:cors_plug, :headers, @headers)
+    Application.put_env(:cors_plug, :methods, ["POST"])
+    Application.put_env(:cors_plug, :origin, cors_plug_origin(cors_origin))
+  end
+
+  defp cors_plug_origin(nil), do: []
+
+  defp cors_plug_origin(origins) do
+    origins
+    |> String.trim()
+    |> String.split(~r{\s*,\s*})
+  end
+end

apps/admin_api/mix.exs

@@ -48,7 +48,7 @@ defmodule AdminAPI.Mixfile do
       {:phoenix, "~> 1.3.0"},
       {:cowboy, "~> 1.0"},
       {:cors_plug, "~> 1.5"},
-      {:sentry, "~> 6.0.0"},
+      {:sentry, "~> 6.2.0"},
       {:bamboo, "~> 0.8"},
       {:bamboo_smtp, "~> 1.4.0"},
       {:bodyguard, "~> 2.2"},

apps/ewallet/config/config.exs

@@ -4,6 +4,6 @@ use Mix.Config
 
 config :ewallet,
   ecto_repos: [],
-  max_per_page: System.get_env("REQUEST_MAX_PER_PAGE") || 100
+  max_per_page: {:system, "REQUEST_MAX_PER_PAGE"}
 
 import_config "#{Mix.env()}.exs"

apps/ewallet/lib/ewallet/web/paginator.ex

@@ -67,7 +67,20 @@ defmodule EWallet.Web.Paginator do
   # Returns the per_page number or default, but never greater than the system's defined limit
   defp get_per_page(attrs) do
     per_page = Map.get(attrs, "per_page", @default_per_page)
-    max_per_page = Application.get_env(:ewallet, :max_per_page, @default_max_per_page)
+
+    max_per_page =
+      case Application.get_env(:ewallet, :max_per_page, @default_max_per_page) do
+        {:system, env_var} ->
+          case System.get_env(env_var) do
+            "" -> @default_max_per_page
+            nil -> @default_max_per_page
+            value when is_binary(value) -> String.to_integer(value)
+            value -> value
+          end
+
+        value ->
+          value
+      end
 
     case per_page do
       n when n > max_per_page -> max_per_page

apps/ewallet/test/ewallet/web/paginator_test.exs

@@ -53,6 +53,17 @@ defmodule EWallet.Web.PaginatorTest do
       Application.delete_env(:ewallet, :max_per_page)
     end
 
+    test "returns per_page if max_per_page is configured as a system tuple" do
+      System.put_env("_TMP_MAX_PER_PAGE", "20")
+      Application.put_env(:ewallet, :max_per_page, {:system, "_TMP_MAX_PER_PAGE"})
+
+      paginator = Paginator.paginate_attrs(Account, %{"per_page" => 100})
+      assert paginator.pagination.per_page == 20
+
+      Application.delete_env(:ewallet, :max_per_page)
+      System.delete_env("_TMP_MAX_PER_PAGE")
+    end
+
     test "returns :error if given attrs.page is a negative integer" do
       result = Paginator.paginate_attrs(Account, %{"page" => -1})
       assert {:error, :invalid_parameter, _} = result

apps/ewallet_api/config/config.exs

@@ -57,7 +57,7 @@ config :mime, :types, %{
 
 # Configs for Sentry exception reporting
 config :sentry,
-  dsn: System.get_env("SENTRY_DSN"),
+  dsn: {:system, "SENTRY_DSN"},
   environment_name: Mix.env(),
   enable_source_code_context: true,
   root_source_code_path: File.cwd!(),

apps/ewallet_api/config/prod.exs

@@ -7,8 +7,8 @@ config :ewallet_api, EWalletAPI.V1.Endpoint,
 # Config for node discovery.
 config :peerage,
   via: Peerage.Via.Dns,
-  dns_name: System.get_env("NODE_DNS") || "localhost",
-  app_name: System.get_env("NODE_NAME") || "ewallet"
+  dns_name: {:system, "NODE_DNS", "localhost"},
+  app_name: {:system, "NODE_NAME", "ewallet"}
 
 # For production, we often load configuration from external
 # sources, such as your system environment. For this reason,

apps/ewallet_api/mix.exs

@@ -52,7 +52,7 @@ defmodule EWalletAPI.Mixfile do
     [
       {:phoenix, "~> 1.3.0"},
       {:cowboy, "~> 1.0"},
-      {:sentry, "~> 6.0.0"},
+      {:sentry, "~> 6.2.0"},
       {:peerage, "~> 1.0.2"},
       {:ewallet_db, in_umbrella: true},
       {:ewallet, in_umbrella: true}

apps/ewallet_db/config/config.exs

@@ -3,15 +3,7 @@ use Mix.Config
 config :ewallet_db,
   ecto_repos: [EWalletDB.Repo],
   env: Mix.env(),
-  base_url: System.get_env("BASE_URL") || "http://localhost:4000",
+  base_url: {:system, "BASE_URL", "http://localhost:4000"},
   min_password_length: 8
 
 import_config "#{Mix.env()}.exs"
-
-storage_adapter = System.get_env("FILE_STORAGE_ADAPTER") || "local"
-
-case storage_adapter do
-  "aws" -> import_config "adapters/aws.exs"
-  "gcs" -> import_config "adapters/gcs.exs"
-  "local" -> import_config "adapters/local.exs"
-end

apps/ewallet_db/config/dev.exs

@@ -2,4 +2,4 @@ use Mix.Config
 
 config :ewallet_db, EWalletDB.Repo,
   adapter: Ecto.Adapters.Postgres,
-  url: System.get_env("DATABASE_URL") || "postgres://localhost/ewallet_dev"
+  url: {:system, "DATABASE_URL", "postgres://localhost/ewallet_dev"}

apps/ewallet_db/config/prod.exs

@@ -2,6 +2,6 @@ use Mix.Config
 
 config :ewallet_db, EWalletDB.Repo,
   adapter: Ecto.Adapters.Postgres,
-  url: System.get_env("DATABASE_URL") || "postgres://localhost/ewallet_prod"
+  url: {:system, "DATABASE_URL", "postgres://localhost/ewallet_prod"}
 
-config :ewallet_db, base_url: System.get_env("BASE_URL")
+config :ewallet_db, base_url: {:system, "BASE_URL"}

apps/ewallet_db/config/test.exs

@@ -3,4 +3,4 @@ use Mix.Config
 config :ewallet_db, EWalletDB.Repo,
   adapter: Ecto.Adapters.Postgres,
   pool: Ecto.Adapters.SQL.Sandbox,
-  url: System.get_env("DATABASE_URL") || "postgres://localhost/ewallet_test"
+  url: {:system, "DATABASE_URL", "postgres://localhost/ewallet_test"}

apps/ewallet_db/lib/ewallet_db/application.ex

@@ -5,9 +5,12 @@ defmodule EWalletDB.Application do
   Kebura's data store lives in this application.
   """
   use Application
+  alias EWalletDB.Config
 
   def start(_type, _args) do
     import Supervisor.Spec
+    DeferredConfig.populate(:ewallet_db)
+    Config.configure_file_storage()
 
     # List all child processes to be supervised
     children = [

apps/ewallet_db/lib/ewallet_db/config.ex

@@ -0,0 +1,43 @@
+defmodule EWalletDB.Config do
+  @moduledoc """
+  Provides a configuration function that are called during application startup.
+  """
+
+  def configure_file_storage do
+    storage_adapter = System.get_env("FILE_STORAGE_ADAPTER") || "local"
+    configure_file_storage(storage_adapter)
+  end
+
+  defp configure_file_storage("aws") do
+    aws_bucket = System.get_env("AWS_BUCKET")
+    aws_region = System.get_env("AWS_REGION")
+    aws_access_key_id = System.get_env("AWS_ACCESS_KEY_ID")
+    aws_secret_access_key = System.get_env("AWS_SECRET_ACCESS_KEY")
+
+    aws_domain = "s3-#{aws_region}.amazonaws.com"
+
+    Application.put_env(:ex_aws, :access_key_id, [aws_access_key_id, :instance_role])
+    Application.put_env(:ex_aws, :secret_access_key, [aws_secret_access_key, :instance_role])
+    Application.put_env(:ex_aws, :region, aws_region)
+    Application.put_env(:ex_aws, :s3, scheme: "https://", host: aws_domain, region: aws_region)
+    Application.put_env(:ex_aws, :debug_requests, true)
+    Application.put_env(:ex_aws, :recv_timeout, 60_000)
+    Application.put_env(:ex_aws, :hackney, recv_timeout: 60_000, pool: false)
+    Application.put_env(:arc, :storage, Arc.Storage.S3)
+    Application.put_env(:arc, :bucket, aws_bucket)
+    Application.put_env(:arc, :asset_host, "https://#{aws_domain}/#{aws_bucket}")
+  end
+
+  defp configure_file_storage("gcs") do
+    gcs_bucket = System.get_env("GCS_BUCKET")
+    gcs_credentials = System.get_env("GCS_CREDENTIALS")
+
+    Application.put_env(:arc, :storage, Arc.Storage.GCS)
+    Application.put_env(:arc, :bucket, gcs_bucket)
+    Application.put_env(:goth, :json, gcs_credentials)
+  end
+
+  defp configure_file_storage("local") do
+    Application.put_env(:arc, :storage, EWallet.Storage.Local)
+  end
+end

apps/ewallet_db/lib/ewallet_db/repo.ex

@@ -1,3 +1,17 @@
 defmodule EWalletDB.Repo do
   use Ecto.Repo, otp_app: :ewallet_db
+
+  # Workaround an issue where ecto.migrate task won't start the app
+  # thus DeferredConfig.populate is not getting called.
+  #
+  # Ecto itself only supports {:system, ENV_VAR} tuple, but not
+  # DeferredConfig's {:system, ENV_VAR, DEFAULT} tuple nor the
+  # {:apply, MFA} tuple.
+  #
+  # See also: https://github.com/mrluc/deferred_config/issues/2
+  def init(_, config) do
+    config
+    |> DeferredConfig.transform_cfg()
+    |> (fn updated -> {:ok, updated} end).()
+  end
 end