slightly improve error tracking related to appsec-config loading

pkg/acquisition/modules/appsec/config.go

@@ -261,6 +261,10 @@ func (w *Source) Configure(ctx context.Context, yamlConfig []byte, logger *log.E
 
 	appsecRuntime, err := appsecCfg.Build(ctx, w.hub)
 	if err != nil {
+		if len(appsecCfg.LoadedFrom) > 0 {
+			return fmt.Errorf("unable to build appsec_config [%s]: %w", strings.Join(appsecCfg.LoadedFrom, ", "), err)
+		}
+
 		return fmt.Errorf("unable to build appsec_config: %w", err)
 	}
 

pkg/appsec/appsec.go

@@ -519,6 +519,10 @@ type AppsecConfig struct {
 
 	LogLevel *log.Level `yaml:"log_level"`
 	Logger   *log.Entry `yaml:"-"`
+
+	// LoadedFrom lists the appsec-config file(s) merged into this config, in load order.
+	// Used to track error origins at load time
+	LoadedFrom []string `yaml:"-"`
 }
 
 func (w *AppsecRuntimeConfig) NewRequestState() AppsecRequestState {
@@ -607,6 +611,8 @@ func (wc *AppsecConfig) LoadByPath(file string) error {
 	// into flat fields. Hooks stay in the phase sections for Build() to compile separately.
 	tmp.normalizePhaseScoped()
 
+	wc.LoadedFrom = append(wc.LoadedFrom, file)
+
 	if wc.Name == "" && tmp.Name != "" {
 		wc.Name = tmp.Name
 	}

pkg/appsec/appsec_config_test.go

@@ -1,6 +1,7 @@
 package appsec
 
 import (
+	"context"
 	"os"
 	"path/filepath"
 	"testing"
@@ -193,6 +194,29 @@
 	// Phase-scoped hook from file 2
 	require.NotNil(t, cfg.InBand)
 	assert.Len(t, cfg.InBand.OnMatch, 1)
+
+	// Both source files are tracked, in load order.
+	assert.Equal(t, []string{f1, f2}, cfg.LoadedFrom)
+}
+
+// A hook filter that fails to compile must surface an error naming the
+// appsec-config file it came from, so `crowdsec -t` points at the faulty config.
+func TestBuildErrorNamesSourceFile(t *testing.T) {
+	cfg := newTestConfig()
+	f := writeTempYAML(t, `
+name: broken-config
+inband:
+  pre_eval:
+    - filter: "req.URL.Path matches '(?i)\\.(css)$'"
+`)
+
+	require.NoError(t, cfg.LoadByPath(f))
+	require.Equal(t, []string{f}, cfg.LoadedFrom)
+
+	// hub is unused: compilation fails before any rule is loaded.
+	_, err := cfg.Build(context.Background(), nil)
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "unable to compile filter")
 }
 
 func TestLoadByPathPhaseOptionsOverride(t *testing.T) {