Weighted Mirroring

szareiangm · April 14, 2019, 5:30am

I saw here in the documentation that the goal was to send “a portion of v1 traffic to v2”: https://preliminary.istio.io/docs/tasks/traffic-management/mirroring/

But at the end %100 was mirrored. I checked the code. Envoy has fractional mirroring and I saw it in some parts of Istio code:

github.com

istio/istio/blob/bc8ba37bb53a0ed17e05c1a1ec67033f65eed1ee/vendor/github.com/envoyproxy/go-control-plane/envoy/api/v2/route/route.pb.go#L1963


	//
	// .. note::
	//
	//   Parsing this field is implemented such that the runtime key's data may be represented
	//   as a :ref:`FractionalPercent <envoy_api_msg_type.FractionalPercent>` proto represented
	//   as JSON/YAML and may also be represented as an integer with the assumption that the value
	//   is an integral percentage out of 100. For instance, a runtime key lookup returning the
	//   value "42" would parse as a `FractionalPercent` whose numerator is 42 and denominator is
	//   HUNDRED. This is behaviour is different to that of the deprecated `runtime_key` field,
	//   where the implicit denominator is 10000.
	RuntimeFraction      *core.RuntimeFractionalPercent `protobuf:"bytes,3,opt,name=runtime_fraction,json=runtimeFraction,proto3" json:"runtime_fraction,omitempty"`
	XXX_NoUnkeyedLiteral struct{}                       `json:"-"`
	XXX_unrecognized     []byte                         `json:"-"`
	XXX_sizecache        int32                          `json:"-"`
}


func (m *RouteAction_RequestMirrorPolicy) Reset()         { *m = RouteAction_RequestMirrorPolicy{} }
func (m *RouteAction_RequestMirrorPolicy) String() string { return proto.CompactTextString(m) }
func (*RouteAction_RequestMirrorPolicy) ProtoMessage()    {}
func (*RouteAction_RequestMirrorPolicy) Descriptor() ([]byte, []int) {
	return fileDescriptor_7dc2895fb75d9d41, []int{5, 0}

https://www.envoyproxy.io/docs/envoy/latest/api-v2/api/v2/route/route.proto#route-routeaction-requestmirrorpolicy

Can someone please give a hint how to enable this feature? We need to mirror %1 or our traffic only.

szareiangm · April 14, 2019, 5:41am

Looks like this feature is not implemented yes:

github.com

istio/istio/blob/bc8ba37bb53a0ed17e05c1a1ec67033f65eed1ee/pilot/pkg/networking/core/v1alpha3/route/route.go#L386


		requestHeadersToRemove = append(requestHeadersToRemove, in.Headers.GetRequest().GetRemove()...)
		requestHeadersToRemove = append(requestHeadersToRemove, in.RemoveRequestHeaders...)
		out.RequestHeadersToRemove = requestHeadersToRemove
		responseHeadersToRemove := make([]string, 0)
		responseHeadersToRemove = append(responseHeadersToRemove, in.Headers.GetResponse().GetRemove()...)
		responseHeadersToRemove = append(responseHeadersToRemove, in.RemoveResponseHeaders...)
		out.ResponseHeadersToRemove = responseHeadersToRemove


		if in.Mirror != nil {
			n := GetDestinationCluster(in.Mirror, serviceRegistry[model.Hostname(in.Mirror.Host)], port)
			action.RequestMirrorPolicy = &route.RouteAction_RequestMirrorPolicy{Cluster: n}
		}


		// TODO: eliminate this logic and use the total_weight option in envoy route
		weighted := make([]*route.WeightedCluster_ClusterWeight, 0)
		for _, dst := range in.Route {
			weight := &types.UInt32Value{Value: uint32(dst.Weight)}
			if dst.Weight == 0 {
				// Ignore 0 weighted clusters if there are other clusters in the route.
				// But if this is the only cluster in the route, then add it as a cluster with weight 100
				if len(in.Route) == 1 {

Did I understand it correctly?

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Weighted Mirroring

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