celCommandOperator             = "%CEL"
	// count of all supported fotmatter, right now is 3(CEL, METADATA and REQ_WITHOUT_QUERY).
	maxFormattersLength = 3

	DevStdout = "/dev/stdout"

	builtinEnvoyAccessLogProvider = "envoy"
)

var (
	// this is used for testing. it should not be changed in regular code.
	clusterLookupFn = LookupCluster