Handle EXTERNAL_URL missing scheme (#1326)

Fixes #1314

.formatter.exs

@@ -1,4 +1,5 @@
 [
+  plugins: [Phoenix.LiveView.HTMLFormatter],
   subdirectories: ["apps/*"],
   inputs: [
     "*.{ex,exs}",

apps/fz_http/priv/repo/migrations/20221224210654_fix_sites_nullable_fields.exs

@@ -1,6 +1,8 @@
 defmodule FzHttp.Repo.Migrations.FixSitesNullableFields do
   use Ecto.Migration
 
+  require Logger
+
   def change do
     dns = System.get_env("WIREGUARD_DNS", "1.1.1.1,1.0.0.1")
     mtu = System.get_env("WIREGUARD_MTU", "1280")
@@ -10,7 +12,7 @@ defmodule FzHttp.Repo.Migrations.FixSitesNullableFields do
     endpoint =
       System.get_env(
         "WIREGUARD_ENDPOINT",
-        URI.parse(System.get_env("EXTERNAL_URL", "https://localhost/")).host
+        host()
       ) <> ":" <> System.get_env("WIREGUARD_PORT", "51820")
 
     execute("""
@@ -43,4 +45,29 @@ defmodule FzHttp.Repo.Migrations.FixSitesNullableFields do
       WHERE endpoint IS NULL
     """)
   end
+
+  defp host do
+    external_url_var = System.get_env("EXTERNAL_URL")
+    substitute = "https://localhost/"
+
+    external_url =
+      if is_nil(external_url_var) || String.length(external_url_var) == 0 do
+        Logger.warn("EXTERNAL_URL is empty! Using #{substitute} as basis for WireGuard endpoint.")
+        substitute
+      else
+        external_url_var
+      end
+
+    parsed_host = URI.parse(external_url).host
+
+    if is_nil(parsed_host) do
+      Logger.warn(
+        "EXTERNAL_URL doesn't seem to contain a valid URL. Assuming https://#{external_url}."
+      )
+
+      external_url
+    else
+      parsed_host
+    end
+  end
 end