added a healthcheck

lib/pinchflat_web/controllers/health_controller.ex

@@ -0,0 +1,9 @@
+defmodule PinchflatWeb.HealthController do
+  use PinchflatWeb, :controller
+
+  def check(conn, _params) do
+    conn
+    |> put_status(:ok)
+    |> json(%{status: "ok"})
+  end
+end

lib/pinchflat_web/router.ex

@@ -47,6 +47,13 @@ defmodule PinchflatWeb.Router do
     get "/media/:uuid/stream", MediaItems.MediaItemController, :stream
   end
 
+  # No auth or CSRF protection for the health check endpoint
+  scope "/", PinchflatWeb do
+    pipe_through :api
+
+    get "/healthcheck", HealthController, :check
+  end
+
   scope "/dev" do
     pipe_through :browser
 

selfhosted.Dockerfile

@@ -113,5 +113,8 @@ COPY --from=builder /app/_build/${MIX_ENV}/rel/pinchflat ./
 # above and adding an entrypoint. See https://github.com/krallin/tini for details
 # ENTRYPOINT ["/tini", "--"]
 
+HEALTHCHECK --interval=120s --start-period=10s \
+  CMD curl --fail http://localhost:${PORT}/healthcheck || exit 1
+
 # Start the app
 CMD ["/app/bin/docker_start"]

test/pinchflat_web/controllers/health_controller_test.exs

@@ -0,0 +1,10 @@
+defmodule PinchflatWeb.HealthControllerTest do
+  use PinchflatWeb.ConnCase
+
+  describe "GET /healthcheck" do
+    test "returns ok", %{conn: conn} do
+      conn = get(conn, "/healthcheck")
+      assert json_response(conn, 200) == %{"status" => "ok"}
+    end
+  end
+end