From ac77ced311e310f71bc0b95b09f75aa7a10706eb Mon Sep 17 00:00:00 2001
From: "Adam C. Stephens" <adam@valkor.net>
Date: Mon, 31 Aug 2026 14:44:30 -0400
Subject: [PATCH] fix: only start the oidcc worker for an issuer that could
 answer

Refs: GS-36

Assisted-By: Claude Opus 5
---
 lib/git_sync/forgejo/provider.ex              | 18 ++++++++-
 .../controllers/session_controller.ex         |  2 +-
 .../controllers/session_html/new.html.heex    |  4 +-
 test/git_sync/forgejo/provider_test.exs       | 38 +++++++++++++++++++
 .../controllers/session_controller_test.exs   | 13 +++++++
 5 files changed, 71 insertions(+), 4 deletions(-)
 create mode 100644 test/git_sync/forgejo/provider_test.exs

diff --git a/lib/git_sync/forgejo/provider.ex b/lib/git_sync/forgejo/provider.ex
index d5dd8c7..d474a9e 100644
--- a/lib/git_sync/forgejo/provider.ex
+++ b/lib/git_sync/forgejo/provider.ex
@@ -6,6 +6,11 @@ defmodule GitSync.Forgejo.Provider do
   started dynamically rather than listed in the application's children. It backs
   off and retries rather than terminating, so a Forgejo instance that is briefly
   unreachable does not leave the app with no way to log in.
+
+  That patience is only worth spending on an issuer that could answer. A
+  development instance points `base_url` at the bare repositories it clones
+  from, and nothing is discoverable over `file://`, so a worker started on one
+  would retry until the instance is shut down.
   """
 
   alias GitSync.Connection
@@ -19,6 +24,14 @@ defmodule GitSync.Forgejo.Provider do
 
   def name, do: @worker
 
+  @doc """
+  Whether a connection's Forgejo could be an OIDC issuer.
+  """
+  def issuer?(%Connection{base_url: base_url}),
+    do: URI.parse(base_url).scheme in ["http", "https"]
+
+  def issuer?(nil), do: false
+
   @doc """
   Starts the worker for `issuer`, replacing one pointing at a different issuer.
   """
@@ -42,8 +55,9 @@ defmodule GitSync.Forgejo.Provider do
   """
   def start_configured do
     case Connections.forgejo() do
-      %Connection{client_id: client_id, base_url: base_url} when is_binary(client_id) ->
-        ensure_started(base_url)
+      %Connection{client_id: client_id, base_url: base_url} = connection
+      when is_binary(client_id) ->
+        if issuer?(connection), do: ensure_started(base_url), else: :ignore
 
       _ ->
         :ignore
diff --git a/lib/git_sync_web/controllers/session_controller.ex b/lib/git_sync_web/controllers/session_controller.ex
index 561eac9..55cc853 100644
--- a/lib/git_sync_web/controllers/session_controller.ex
+++ b/lib/git_sync_web/controllers/session_controller.ex
@@ -20,7 +20,7 @@ defmodule GitSyncWeb.SessionController do
   plug Oidcc.Plug.AuthorizationCallback, @client when action == :callback
 
   def new(conn, _params) do
-    render(conn, :new)
+    render(conn, :new, forgejo_issuer?: Provider.issuer?(Connections.forgejo()))
   end
 
   def create(conn, _params) do
diff --git a/lib/git_sync_web/controllers/session_html/new.html.heex b/lib/git_sync_web/controllers/session_html/new.html.heex
index 211b740..d993a38 100644
--- a/lib/git_sync_web/controllers/session_html/new.html.heex
+++ b/lib/git_sync_web/controllers/session_html/new.html.heex
@@ -4,7 +4,9 @@
     <:subtitle>git-sync is gated by your Forgejo instance.</:subtitle>
   </.header>
 
-  <.button id="sign-in" href={~p"/auth/forgejo"} method="post">Sign in with Forgejo</.button>
+  <.button :if={@forgejo_issuer?} id="sign-in" href={~p"/auth/forgejo"} method="post">
+    Sign in with Forgejo
+  </.button>
 
   <.dev_sign_in />
 </Layouts.app>
diff --git a/test/git_sync/forgejo/provider_test.exs b/test/git_sync/forgejo/provider_test.exs
new file mode 100644
index 0000000..a28b160
--- /dev/null
+++ b/test/git_sync/forgejo/provider_test.exs
@@ -0,0 +1,38 @@
+defmodule GitSync.Forgejo.ProviderTest do
+  use GitSync.DataCase
+
+  alias GitSync.Connection
+  alias GitSync.Forgejo.Provider
+
+  describe "issuer?/1" do
+    test "an instance reached over HTTP can be one" do
+      assert Provider.issuer?(%Connection{base_url: "https://forge.test"})
+    end
+
+    test "the repositories a development instance clones from cannot" do
+      refute Provider.issuer?(%Connection{base_url: "file:///srv/dev_repos/forgejo"})
+    end
+
+    test "an instance nobody has configured cannot" do
+      refute Provider.issuer?(nil)
+    end
+  end
+
+  describe "start_configured/0" do
+    test "leaves the worker down for an instance that cannot be an issuer" do
+      Repo.insert!(%Connection{
+        kind: :forgejo,
+        base_url: "file:///srv/dev_repos/forgejo",
+        client_id: "dev",
+        client_secret: "dev"
+      })
+
+      assert Provider.start_configured() == :ignore
+      refute Process.whereis(Provider.name())
+    end
+
+    test "leaves it down until the wizard has run" do
+      assert Provider.start_configured() == :ignore
+    end
+  end
+end
diff --git a/test/git_sync_web/controllers/session_controller_test.exs b/test/git_sync_web/controllers/session_controller_test.exs
index 393ac32..c416db9 100644
--- a/test/git_sync_web/controllers/session_controller_test.exs
+++ b/test/git_sync_web/controllers/session_controller_test.exs
@@ -13,6 +13,19 @@ defmodule GitSyncWeb.SessionControllerTest do
     assert html_response(conn, 200) =~ "Sign in with Forgejo"
   end
 
+  test "the page does not offer a Forgejo that cannot be an issuer", %{
+    conn: conn,
+    connection: connection
+  } do
+    connection
+    |> Ecto.Changeset.change(base_url: "file:///srv/dev_repos/forgejo")
+    |> GitSync.Repo.update!()
+
+    conn = get(conn, ~p"/login")
+
+    refute html_response(conn, 200) =~ "Sign in with Forgejo"
+  end
+
   describe "with a live provider" do
     setup %{connection: connection} do
       issuer = OidcProvider.start(subject: "alice", client_id: connection.client_id)
-- 
2.51.2