From 5dfc77a2d68517884c2a1454be13736b0fcb5e4a Mon Sep 17 00:00:00 2001
From: Nikita Volodin <volodin.n@gmail.com>
Date: Mon, 29 Apr 2024 01:54:28 -0400
Subject: [PATCH] feat(prose/filter): inject span context in w3c format for
 presidio

---
 .../internal/common/otel_propagator.go        | 56 +++++++++++++++++++
 .../internal/common/pii_analysis.go           | 20 ++++++-
 2 files changed, 75 insertions(+), 1 deletion(-)
 create mode 100644 privacy-profile-composer/pkg/envoyfilter/internal/common/otel_propagator.go

diff --git a/privacy-profile-composer/pkg/envoyfilter/internal/common/otel_propagator.go b/privacy-profile-composer/pkg/envoyfilter/internal/common/otel_propagator.go
new file mode 100644
index 00000000..d1a653ad
--- /dev/null
+++ b/privacy-profile-composer/pkg/envoyfilter/internal/common/otel_propagator.go
@@ -0,0 +1,56 @@
+package common
+
+import (
+	"fmt"
+
+	"github.com/openzipkin/zipkin-go/model"
+	"go.opentelemetry.io/otel/propagation"
+	"go.opentelemetry.io/otel/trace"
+)
+
+var GlobalOtelPropagator = propagation.NewCompositeTextMapPropagator(
+	propagation.TraceContext{},
+	propagation.Baggage{},
+)
+
+func otelSpanContextFromZipkin(span model.SpanContext) (trace.SpanContext, error) {
+	traceFlags := trace.TraceFlags(0)
+	if span.Sampled == nil {
+		traceFlags = traceFlags.WithSampled(false)
+	} else {
+		traceFlags = traceFlags.WithSampled(*span.Sampled)
+	}
+
+	traceID, err := trace.TraceIDFromHex(fmt.Sprintf("%032s", span.TraceID.String()))
+	if err != nil {
+		return trace.NewSpanContext(
+			trace.SpanContextConfig{
+				TraceFlags: traceFlags,
+				TraceState: trace.TraceState{},
+				Remote:     false,
+			},
+		), fmt.Errorf("invalid trace ID: %w", err)
+	}
+
+	spanID, err := trace.SpanIDFromHex(span.ID.String())
+	if err != nil {
+		return trace.NewSpanContext(
+			trace.SpanContextConfig{
+				TraceID:    traceID,
+				TraceFlags: traceFlags,
+				TraceState: trace.TraceState{},
+				Remote:     false,
+			},
+		), fmt.Errorf("invalid span ID: %w", err)
+	}
+
+	return trace.NewSpanContext(
+		trace.SpanContextConfig{
+			TraceID:    traceID,
+			SpanID:     spanID,
+			TraceFlags: traceFlags,
+			TraceState: trace.TraceState{},
+			Remote:     false,
+		},
+	), nil
+}
diff --git a/privacy-profile-composer/pkg/envoyfilter/internal/common/pii_analysis.go b/privacy-profile-composer/pkg/envoyfilter/internal/common/pii_analysis.go
index 8a01c073..db0d3623 100644
--- a/privacy-profile-composer/pkg/envoyfilter/internal/common/pii_analysis.go
+++ b/privacy-profile-composer/pkg/envoyfilter/internal/common/pii_analysis.go
@@ -7,6 +7,9 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+
+	"go.opentelemetry.io/otel/propagation"
+	"go.opentelemetry.io/otel/trace"
 )
 
 type PresidioDataFormat struct {
@@ -18,6 +21,13 @@ func PiiAnalysis(ctx context.Context, presidioSvcURL string, svcName string, buf
 	span, ctx := GlobalTracer.StartSpanFromContext(ctx, "PiiAnalysis")
 	defer span.Finish()
 
+	otelSpanCtx, err := otelSpanContextFromZipkin(span.Context())
+	if err != nil {
+		fmt.Printf("Error converting span context: %v\n", err)
+	}
+
+	ctx = trace.ContextWithSpanContext(ctx, otelSpanCtx)
+
 	empty := []string{}
 
 	msgString, err := json.Marshal(
@@ -30,7 +40,15 @@ func PiiAnalysis(ctx context.Context, presidioSvcURL string, svcName string, buf
 		return empty, fmt.Errorf("could not convert data for presidio into json: %w", err)
 	}
 
-	resp, err := http.Post(presidioSvcURL, "application/json", bytes.NewBuffer(msgString))
+	req, err := http.NewRequest("POST", presidioSvcURL, bytes.NewBuffer(msgString))
+	if err != nil {
+		return empty, fmt.Errorf("could not create new request object: %w", err)
+	}
+
+	req.Header.Set("Content-Type", "application/json")
+	GlobalOtelPropagator.Inject(ctx, propagation.HeaderCarrier(req.Header))
+
+	resp, err := http.DefaultClient.Do(req)
 	if err != nil {
 		return empty, fmt.Errorf("presidio post error: %w", err)
 	}