fix(nginx): Refresh Lua assets during upgrades

internal/infra/manager.go

@@ -712,16 +712,55 @@ func (m *Manager) EnsureBaseNginxConfig() error {
 	if err != nil {
 		return err
 	}
-	if string(nginxConf) == string(existing) {
-		return nil
+	changed, err := writeFileIfChanged(confPath, nginxConf, 0644)
+	if err != nil {
+		return err
 	}
 
-	if err := os.WriteFile(confPath, nginxConf, 0644); err != nil {
-		return err
+	if luaEnabled {
+		luaDir := filepath.Join(nginxDir, "lua")
+		if err := os.MkdirAll(luaDir, 0755); err != nil {
+			return err
+		}
+		agentIP := m.GetDockerHostIP()
+		agentPort := m.GetAgentPort()
+		securityLua, err := templates.GetNginxSecurityLuaWithConfig(agentIP, agentPort, m.config.Security.InternalAPIToken, m.config.Security.TrustedProxies, m.config.Security.TrustCFHeader)
+		if err != nil {
+			return err
+		}
+		securityChanged, err := writeFileIfChanged(filepath.Join(luaDir, "security.lua"), securityLua, 0644)
+		if err != nil {
+			return err
+		}
+		changed = changed || securityChanged
+
+		trafficLua, err := templates.GetNginxTrafficLuaWithConfig(agentIP, agentPort)
+		if err != nil {
+			return err
+		}
+		trafficChanged, err := writeFileIfChanged(filepath.Join(luaDir, "traffic.lua"), trafficLua, 0644)
+		if err != nil {
+			return err
+		}
+		changed = changed || trafficChanged
+
+		errorPage, err := templates.GetErrorPage()
+		if err != nil {
+			return err
+		}
+		errorPagePath := filepath.Join(nginxDir, "html", ".flatrun", "error.html")
+		if err := os.MkdirAll(filepath.Dir(errorPagePath), 0755); err != nil {
+			return err
+		}
+		errorPageChanged, err := writeFileIfChanged(errorPagePath, errorPage, 0644)
+		if err != nil {
+			return err
+		}
+		changed = changed || errorPageChanged
+	}
+	if changed {
+		_ = m.reloadNginx()
 	}
-	// Best-effort reload: the rewritten config also takes effect on the next nginx
-	// restart, so a reload failure here (e.g. container not yet ready) is not fatal.
-	_ = m.reloadNginx()
 	return nil
 }
 
@@ -1456,5 +1495,20 @@ func writeNginxErrorPage(nginxDir string) error {
 	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
 		return err
 	}
-	return os.WriteFile(path, content, 0644)
+	_, err = writeFileIfChanged(path, content, 0644)
+	return err
+}
+
+func writeFileIfChanged(path string, content []byte, mode os.FileMode) (bool, error) {
+	existing, err := os.ReadFile(path)
+	if err == nil && bytes.Equal(existing, content) {
+		return false, nil
+	}
+	if err != nil && !os.IsNotExist(err) {
+		return false, err
+	}
+	if err := os.WriteFile(path, content, mode); err != nil {
+		return false, err
+	}
+	return true, nil
 }

internal/infra/manager_test.go

@@ -7,6 +7,7 @@ import (
 	"testing"
 
 	"github.com/flatrun/agent/pkg/config"
+	"github.com/flatrun/agent/templates"
 )
 
 func TestSetNginxRealtimeCapture(t *testing.T) {
@@ -240,6 +241,54 @@ func TestEnsureBaseNginxConfig(t *testing.T) {
 		if !strings.Contains(string(content), "server_names_hash_bucket_size") {
 			t.Errorf("refreshed config should contain server_names_hash_bucket_size, got:\n%s", content)
 		}
+		securityLua, err := os.ReadFile(filepath.Join(nginxDir, "lua", "security.lua"))
+		if err != nil {
+			t.Fatal(err)
+		}
+		if !strings.Contains(string(securityLua), "function _M.prepare_error_response()") {
+			t.Errorf("refreshed security.lua is missing error response support")
+		}
+		if _, err := os.Stat(filepath.Join(nginxDir, "lua", "traffic.lua")); err != nil {
+			t.Fatal(err)
+		}
+		if _, err := os.Stat(filepath.Join(nginxDir, "html", ".flatrun", "error.html")); err != nil {
+			t.Fatal(err)
+		}
+	})
+
+	t.Run("refreshes stale lua beside a current config", func(t *testing.T) {
+		nginxDir := t.TempDir()
+		confPath := filepath.Join(nginxDir, "nginx.conf")
+		current, err := templates.GetNginxConfigWithData(true, templates.NginxConfigData{})
+		if err != nil {
+			t.Fatal(err)
+		}
+		if err := os.WriteFile(confPath, current, 0644); err != nil {
+			t.Fatal(err)
+		}
+		luaDir := filepath.Join(nginxDir, "lua")
+		if err := os.MkdirAll(luaDir, 0755); err != nil {
+			t.Fatal(err)
+		}
+		if err := os.WriteFile(filepath.Join(luaDir, "security.lua"), []byte("return {}\n"), 0644); err != nil {
+			t.Fatal(err)
+		}
+
+		cfg := &config.Config{
+			DeploymentsPath: nginxDir,
+			Nginx:           config.NginxConfig{ConfigPath: filepath.Join(nginxDir, "conf.d")},
+		}
+		if err := NewManager(cfg).EnsureBaseNginxConfig(); err != nil {
+			t.Fatalf("EnsureBaseNginxConfig() = %v", err)
+		}
+
+		securityLua, err := os.ReadFile(filepath.Join(luaDir, "security.lua"))
+		if err != nil {
+			t.Fatal(err)
+		}
+		if !strings.Contains(string(securityLua), "function _M.prepare_error_response()") {
+			t.Errorf("stale security.lua was not refreshed")
+		}
 	})
 
 	t.Run("does not create a config where none exists", func(t *testing.T) {