[OTEL-2125] Add configsync to otel-agent without DD exporter config

cmd/otel-agent/subcommands/run/command.go

@@ -25,6 +25,7 @@ import (
 	"github.com/DataDog/datadog-agent/comp/core/hostname/hostnameinterface"
 	"github.com/DataDog/datadog-agent/comp/core/hostname/remotehostnameimpl"
 	log "github.com/DataDog/datadog-agent/comp/core/log/def"
+	logfx "github.com/DataDog/datadog-agent/comp/core/log/fx"
 	logtracefx "github.com/DataDog/datadog-agent/comp/core/log/fx-trace"
 	"github.com/DataDog/datadog-agent/comp/core/secrets"
 	tagger "github.com/DataDog/datadog-agent/comp/core/tagger/def"
@@ -106,8 +107,20 @@ func runOTelAgentCommand(ctx context.Context, params *subcommands.GlobalParams,
 			fx.Provide(func() coreconfig.Component {
 				return acfg
 			}),
+			fx.Provide(func(_ coreconfig.Component) log.Params {
+				return log.ForDaemon(params.LoggerName, "log_file", pkgconfigsetup.DefaultOTelAgentLogFile)
+			}),
+			logfx.Module(),
+			fetchonlyimpl.Module(),
+			// TODO: don't rely on this pattern; remove this `OptionalModuleWithParams` thing
+			//       and instead adapt OptionalModule to allow parameter passing naturally.
+			//       See: https://github.com/DataDog/datadog-agent/pull/28386
+			configsyncimpl.OptionalModuleWithParams(),
+			fx.Provide(func() configsyncimpl.Params {
+				return configsyncimpl.NewParams(params.SyncTimeout, params.SyncDelay, true)
+			}),
 			converterfx.Module(),
-			fx.Provide(func(cp converter.Component) confmap.Converter {
+			fx.Provide(func(cp converter.Component, _ optional.Option[configsync.Component]) confmap.Converter {
 				return cp
 			}),
 			collectorcontribFx.Module(),

comp/otelcol/ddflareextension/impl/server.go

@@ -116,7 +116,7 @@ func newServer(endpoint string, handler http.Handler, auth bool) (*server, error
 	// no easy way currently to pass required bearer auth token to OSS collector;
 	// skip the validation if running inside a separate collector
 	// TODO: determine way to allow OSS collector to authenticate with agent, OTEL-2226
-	if auth {
+	if auth && util.GetAuthToken() != "" {
 		r.Use(validateToken)
 	}