feat(api): warn at startup when the debug route has no authentication

pkg/modules/api/api_test.go

@@ -1,6 +1,8 @@
 package api
 
 import (
+	"bytes"
+	"log/slog"
 	"strings"
 	"testing"
 )
@@ -65,3 +67,68 @@ func TestApi_Validate_Auth(t *testing.T) {
 		})
 	}
 }
+
+func TestApi_warnInsecureDebugRoute(t *testing.T) {
+	for _, tc := range []struct {
+		scenario     string
+		api          Api
+		expectWarn   bool
+		expectFields []string
+	}{
+		{
+			scenario:     "debug route on with no auth warns",
+			api:          Api{enableDebugRoute: true},
+			expectWarn:   true,
+			expectFields: []string{"--api-enable-debug-route", "API_ENABLE_DEBUG_ROUTE", "--api-enable-basic-auth", "API_ENABLE_BASIC_AUTH", "--api-enable-oidc-auth", "API_ENABLE_OIDC_AUTH"},
+		},
+		{
+			scenario:   "debug route off is silent",
+			api:        Api{enableDebugRoute: false},
+			expectWarn: false,
+		},
+		{
+			scenario:   "basic auth silences it",
+			api:        Api{enableDebugRoute: true, basicAuthUsername: "foo"},
+			expectWarn: false,
+		},
+		{
+			scenario:   "oidc silences it",
+			api:        Api{enableDebugRoute: true, oidcEnabled: true},
+			expectWarn: false,
+		},
+	} {
+		t.Run(tc.scenario, func(t *testing.T) {
+			buf := new(bytes.Buffer)
+			tc.api.logger = slog.New(slog.NewJSONHandler(buf, &slog.HandlerOptions{Level: slog.LevelWarn}))
+
+			tc.api.warnInsecureDebugRoute()
+
+			logged := buf.String()
+			if !tc.expectWarn {
+				if logged != "" {
+					t.Fatalf("expected no warning, got: %s", logged)
+				}
+				return
+			}
+
+			if logged == "" {
+				t.Fatal("expected a warning, got none")
+			}
+			// Every flag named must carry its environment variable.
+			for _, want := range tc.expectFields {
+				if !strings.Contains(logged, want) {
+					t.Fatalf("warning does not mention %q: %s", want, logged)
+				}
+			}
+			if strings.Contains(logged, "—") {
+				t.Fatalf("warning must not contain an em dash: %s", logged)
+			}
+		})
+	}
+}
+
+// The warning reads a.logger, which is nil until Provision assigns it.
+func TestApi_warnInsecureDebugRoute_NilLoggerDoesNotPanic(t *testing.T) {
+	api := Api{enableDebugRoute: true}
+	api.warnInsecureDebugRoute()
+}