Log loaded config at debug level

cmd/main.go

@@ -21,6 +21,7 @@ import (
 	"github.com/tetratelabs/log"
 	"github.com/tetratelabs/run"
 	"github.com/tetratelabs/run/pkg/signal"
+	"github.com/tetratelabs/telemetry"
 
 	"github.com/tetrateio/authservice-go/internal"
 	"github.com/tetrateio/authservice-go/internal/server"
@@ -34,11 +35,20 @@ func main() {
 		authzServer = server.New(&configFile.Config, authz.Register)
 	)
 
+	configLog := run.NewPreRunner("config-log", func() error {
+		cfgLog := internal.Logger(internal.Config)
+		if cfgLog.Level() == telemetry.LevelDebug {
+			cfgLog.Debug("configuration loaded", "config", internal.ConfigToJSONString(&configFile.Config))
+		}
+		return nil
+	})
+
 	g := run.Group{Logger: internal.Logger(internal.Default)}
 
 	g.Register(
 		configFile,        // load the configuration
 		logging,           // set up the logging system
+		configLog,         // log the configuration
 		authzServer,       // start the server
 		&signal.Handler{}, // handle graceful termination
 	)

internal/config.go

@@ -66,3 +66,8 @@ func (l *LocalConfigFile) Validate() error {
 
 	return l.Config.ValidateAll()
 }
+
+func ConfigToJSONString(c *configv1.Config) string {
+	b, _ := protojson.Marshal(c)
+	return string(b)
+}

internal/config_test.go

@@ -95,3 +95,23 @@ func TestLoadMock(t *testing.T) {
 	require.NoError(t, err)
 	require.True(t, proto.Equal(want, &cfg.Config))
 }
+
+func TestConfigToJSONString(t *testing.T) {
+	tests := []struct {
+		name   string
+		config *configv1.Config
+		want   string
+	}{
+		{"nil", nil, "{}"},
+		{"empty", &configv1.Config{}, "{}"},
+		{"simple", &configv1.Config{ListenPort: 8080}, `{"listenPort":8080}`},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := ConfigToJSONString(tt.config)
+			require.JSONEq(t, tt.want, got)
+		})
+	}
+
+}

internal/logging.go

@@ -28,6 +28,7 @@ import (
 
 const (
 	Authz    = "authz"
+	Config   = "config"
 	Default  = "default"
 	Requests = "requests"
 	Server   = "server"
@@ -37,6 +38,7 @@ const (
 // scopes contains the list of all logging scopes
 var scopes = map[string]string{
 	Authz:    "Envoy ext-authz filter implementation messages",
+	Config:   "Configuration messages",
 	Default:  "Default",
 	Requests: "Logs all requests and responses received by the server",
 	Server:   "Server request handling messages",