fix: boot beacon even without defined beacon_site routes in host app … (#699)

* fix: boot beacon even without defined beacon_site routes in host app router

* clean up

* docs

Author: leandrocp

guides/general/troubleshooting.md

@@ -29,10 +29,14 @@ a site prefix can never match and it will never receive requests.
 
 That's is not necessarily an error if you have multiple sites in the same project
 and each scope is filtering requests on the `:host` option.
+But it may indicate:
 
-But it may indicate an invalid configuration, as a preceding route matching the prefix
+1. An invalid configuration, as a preceding route matching the prefix
 that was supposed to be handled by this site, or an invalid `:host` value.
 
+2. Missing `use Beacon.Router` and/or missing `beacon_site` in your
+app's router file.
+
 Note that if you're using `:host` on the scope and running in `localhost`,
 consider adding `"localhost"` to the list of allowed hosts.
 
@@ -41,4 +45,4 @@ Also check the [Beacon.Router](https://hexdocs.pm/beacon/Beacon.Router.html) for
 ## RuntimeError - could not find persistent term for endpoint
 
 `Beacon` should be started after your host's `Endpoint`, please review the application children
-and make sure is declared after the endpoint.
+and make sure is declared after the endpoint.

lib/beacon/router.ex

@@ -270,7 +270,10 @@ defmodule Beacon.Router do
   # match and invalidate the `beacon_site` mount.
   def reachable?(%Beacon.Config{} = config, opts \\ []) do
     %{site: site, endpoint: endpoint, router: router} = config
+    function_exported?(router, :__beacon_scoped_prefix_for_site__, 1) && reachable?(site, endpoint, router, opts)
+  end
 
+  defp reachable?(site, endpoint, router, opts) do
     host = Keyword.get_lazy(opts, :host, fn -> endpoint.host() end)
 
     prefix =

test/beacon/registry_test.exs

@@ -12,6 +12,7 @@ defmodule Beacon.RegistryTest do
              :lifecycle_test,
              :lifecycle_test_fail,
              :my_site,
+             :no_routes,
              :not_booted,
              :raw_schema_test,
              :s3_site

test/beacon/router_test.exs

@@ -86,5 +86,10 @@ defmodule Beacon.RouterTest do
     test "do not match any existing host/path", %{config: config} do
       refute Router.reachable?(config, host: nil, prefix: "/nested/invalid")
     end
+
+    test "router without beacon routes" do
+      config = Beacon.Config.fetch!(:no_routes)
+      refute Router.reachable?(config)
+    end
   end
 end

test/support/router.ex renamed to test/support/routers.ex

@@ -1,3 +1,7 @@
+defmodule Beacon.BeaconTest.NoRoutesRouter do
+  use Beacon.BeaconTest.Web, :router
+end
+
 defmodule Beacon.BeaconTest.Router do
   use Beacon.BeaconTest.Web, :router
   use Beacon.Router

test/test_helper.exs

@@ -50,6 +50,13 @@ Supervisor.start_link(
          router: Beacon.BeaconTest.Router,
          repo: Beacon.BeaconTest.Repo
        ],
+       [
+         site: :no_routes,
+         mode: :testing,
+         endpoint: Beacon.BeaconTest.Endpoint,
+         router: Beacon.BeaconTest.NoRoutesRouter,
+         repo: Beacon.BeaconTest.Repo
+       ],
        [
          site: :not_booted,
          mode: :testing,