web: evaluated static paths at runtime

lib/ha_handler.ex

@@ -15,9 +15,21 @@ defmodule HAHandler do
 
   def acme_challenge_path, do: Application.get_env(@otp_app, :acme_challenge_path)
   def static_path(), do: Application.app_dir(@otp_app, "priv/static/")
-  def template_dir(), do: "lib/ha_handler/web/templates"
 
   def otp_app(), do: @otp_app
   def version(), do: @version
   def env(), do: @env
+
+  def acme_challenges_static_config() do
+    [
+      at: "/.well-known/acme-challenge/",
+      from: acme_challenge_path()
+    ]
+  end
+  def assets_static_config() do
+    [
+      at: "/static",
+      from: static_path()
+    ]
+  end
 end

lib/ha_handler/web/router.ex

@@ -8,25 +8,21 @@ defmodule HAHandler.Web.Router do
 
 	use Plug.Router
 
-	import HAHandler, only: [acme_challenge_path: 0, static_path: 0]
-
 	alias HAHandler.Web.Controller
 
 	# Note for plugs: oder is important, as a plug may stop
 	# want to stop the pipeline!
 
 	plug Plug.Logger, log: :debug
-	# Note: `plug` is a macro, hence evaluated at
-	# compile-time. The configuration (which path to
-	# serve) cannot be modified at runtime with this
-	# system.
-	plug Plug.Static,
-		at: "/.well-known/acme-challenge/",
-		from: acme_challenge_path()
 
-	plug Plug.Static,
-		at: "/static",
-		from: static_path()
+	# We use replug to allow for runtime configuration in release (as macros such
+	# as the `plug` call ae evaluated are compile-time).
+	plug Replug,
+		plug: Plug.Static,
+		opts: {HAHandler, :acme_challenges_static_config}
+	plug Replug,
+		plug: Plug.Static,
+		opts: {HAHandler, :assets_static_config}
 
 	plug :match
 	plug :dispatch

mix.exs

@@ -25,6 +25,7 @@ defmodule HAHandler.MixProject do
     [
       {:plug, "~> 1.12"},
       {:plug_cowboy, "~> 2.5"},
+      {:replug, "~> 0.1.0"},
       {:procket, "~> 0.9"},
       {:poison, "~> 5.0"},
       {:postgrex, "~> 0.16.1"}

mix.lock

@@ -14,6 +14,7 @@
   "postgrex": {:hex, :postgrex, "0.16.1", "f94628a32c571266f53cd1e5fca705e626e2417bf1eee6f868985d14e874160a", [:mix], [{:connection, "~> 1.1", [hex: :connection, repo: "hexpm", optional: false]}, {:db_connection, "~> 2.1", [hex: :db_connection, repo: "hexpm", optional: false]}, {:decimal, "~> 1.5 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}], "hexpm", "6b225df32c857b9430619dbe30200a7ae664e23415a771ae9209396ee8eeee64"},
   "procket": {:hex, :procket, "0.9.5", "ce91c00cb3f4d627fb3827f46ce68e6a969ea265df1afb349c300a07be4bb16c", [:rebar3], [], "hexpm", "1288bba5eb6f08ea5df3dda9e051bdac8f4b1e50adcca5cf4d726e825ad81bed"},
   "ranch": {:hex, :ranch, "1.8.0", "8c7a100a139fd57f17327b6413e4167ac559fbc04ca7448e9be9057311597a1d", [:make, :rebar3], [], "hexpm", "49fbcfd3682fab1f5d109351b61257676da1a2fdbe295904176d5e521a2ddfe5"},
+  "replug": {:hex, :replug, "0.1.0", "61d35f8c873c0078a23c49579a48f36e45789414b1ec0daee3fd5f4e34221f23", [:mix], [{:plug, "~> 1.8", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm", "f71f7a57e944e854fe4946060c6964098e53958074c69fb844b96e0bd58cfa60"},
   "sweet_xml": {:hex, :sweet_xml, "0.7.2", "4729f997286811fabdd8288f8474e0840a76573051062f066c4b597e76f14f9f", [:mix], [], "hexpm", "6894e68a120f454534d99045ea3325f7740ea71260bc315f82e29731d570a6e8"},
   "telemetry": {:hex, :telemetry, "1.0.0", "0f453a102cdf13d506b7c0ab158324c337c41f1cc7548f0bc0e130bbf0ae9452", [:rebar3], [], "hexpm", "73bc09fa59b4a0284efb4624335583c528e07ec9ae76aca96ea0673850aec57a"},
 }