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Add flag to divert V2 traffic to new backend #1734

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Merged
n-h-diaz merged 8 commits into from
Jan 26, 2026
Merged

Add flag to divert V2 traffic to new backend #1734

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c8e3fc2
Add flag to divert V2 traffic to new backend
n-h-diaz Jan 22, 2026
9cade5b
fix
n-h-diaz Jan 22, 2026
acd9a83
fix
n-h-diaz Jan 22, 2026
d684ffd
fix
n-h-diaz Jan 22, 2026
ee92750
Merge branch 'master' into dd
n-h-diaz Jan 23, 2026
321ed15
Merge branch 'master' into dd
n-h-diaz Jan 26, 2026
8093da7
log
n-h-diaz Jan 26, 2026
d8c7de1
Merge branch 'dd' of https://github.com/n-h-diaz/mixer into dd
n-h-diaz Jan 26, 2026
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1 change: 1 addition & 0 deletions deploy/featureflags/local.yaml
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Original file line number Diff line number Diff line change
Expand Up @@ -3,3 +3,4 @@ flags:
V3MirrorFraction: 1.0
UseSpannerGraph: true
UseStaleReads: true
V2DivertFraction: 1.0
9 changes: 9 additions & 0 deletions internal/featureflags/featureflags.go
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Expand Up @@ -38,6 +38,8 @@ type Flags struct {
UseStaleReads bool `yaml:"UseStaleReads"`
// Whether to enable the embeddings resolver.
EnableEmbeddingsResolver bool `yaml:"EnableEmbeddingsResolver"`
// Fraction of V2 API requests to divert to the new dispatcher backend. Value from 0 to 1.0.
V2DivertFraction float64 `yaml:"V2DivertFraction"`
}

// setDefaultValues creates a new Flags struct with default values.
Expand All @@ -49,6 +51,7 @@ func setDefaultValues() *Flags {
SpannerGraphDatabase: "",
UseStaleReads: false,
EnableEmbeddingsResolver: false,
V2DivertFraction: 0.0,
}
}

Expand All @@ -66,6 +69,12 @@ func (f *Flags) validateFlagValues() error {
if f.UseStaleReads && !f.UseSpannerGraph {
return fmt.Errorf("UseStaleReads requires UseSpannerGraph to be true")
}
if f.V2DivertFraction < 0 || f.V2DivertFraction > 1.0 {
return fmt.Errorf("V2DivertFraction must be between 0 and 1.0, got %f", f.V2DivertFraction)
}
if f.V2DivertFraction > 0 && !f.EnableV3 {
return fmt.Errorf("V2DivertFraction > 0 requires EnableV3 to be true")
}
return nil
}

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10 changes: 10 additions & 0 deletions internal/server/handler_v2.go
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Expand Up @@ -18,12 +18,14 @@ package server
import (
"context"
"log/slog"
"math/rand"
"time"

"github.com/datacommonsorg/mixer/internal/log"
"github.com/datacommonsorg/mixer/internal/merger"
pb "github.com/datacommonsorg/mixer/internal/proto"
pbv2 "github.com/datacommonsorg/mixer/internal/proto/v2"
"github.com/datacommonsorg/mixer/internal/server/datasources"
"github.com/datacommonsorg/mixer/internal/server/pagination"
"github.com/datacommonsorg/mixer/internal/server/statvar/search"
"github.com/datacommonsorg/mixer/internal/server/translator"
Expand Down Expand Up @@ -105,6 +107,10 @@ func (s *Server) V2Resolve(
func (s *Server) V2Node(ctx context.Context, in *pbv2.NodeRequest) (
*pbv2.NodeResponse, error,
) {
if rand.Float64() < s.flags.V2DivertFraction {
return s.dispatcher.Node(ctx, in, datasources.DefaultPageSize)
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@keyurva keyurva Jan 24, 2026

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nit: Should we add a log message when traffic is diverted? If we do, add for obs as well.

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@n-h-diaz n-h-diaz Jan 26, 2026

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Good idea - aded a basic slog message for now. As a follow up I can try to add more detailed metrics for tracking this

}

v2StartTime := time.Now()
errGroup, errCtx := errgroup.WithContext(ctx)
localRespChan := make(chan *pbv2.NodeResponse, 1)
Expand Down Expand Up @@ -260,6 +266,10 @@ func (s *Server) V2Event(
func (s *Server) V2Observation(
ctx context.Context, in *pbv2.ObservationRequest,
) (*pbv2.ObservationResponse, error) {
if rand.Float64() < s.flags.V2DivertFraction {
return s.dispatcher.Observation(ctx, in)
}

v2StartTime := time.Now()

surface, toRemote := util.GetMetadata(ctx)
Expand Down
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