From b531b37167f6a63f63443eae57410ca6da569c23 Mon Sep 17 00:00:00 2001
From: Andrew Steurer <94206073+asteurer@users.noreply.github.com>
Date: Sun, 22 Mar 2026 03:10:57 +0100
Subject: [PATCH] fix: logs are now associated with a trace id in the go and ts
 example applications

Signed-off-by: Andrew Steurer <94206073+asteurer@users.noreply.github.com>
---
 go/examples/spin-basic/main.go      | 20 ++++++++++----------
 go/tracing/conversions.go           |  9 +++++++--
 ts/examples/spin-basic/src/index.ts | 14 ++++++++------
 ts/src/logs.ts                      |  7 ++++---
 4 files changed, 29 insertions(+), 21 deletions(-)

diff --git a/go/examples/spin-basic/main.go b/go/examples/spin-basic/main.go
index eed209e..3cb04de 100644
--- a/go/examples/spin-basic/main.go
+++ b/go/examples/spin-basic/main.go
@@ -24,16 +24,6 @@ func init() {
 	spinhttp.Handle(func(w http.ResponseWriter, r *http.Request) {
 		ctx := context.Background()
 
-		/*
-			### LOGS ###
-		*/
-		loggerProvider := log.NewLoggerProvider(log.WithProcessor(wasiLogs.NewWasiLogProcessor()))
-		logger := loggerProvider.Logger("spin-logs")
-		logRecord := logApi.Record{}
-		logRecord.SetBody(logApi.StringValue("Hello from Go!"))
-		logRecord.SetSeverity(logApi.SeverityInfo)
-		logger.Emit(ctx, logRecord)
-
 		/*
 			### METRICS ###
 		*/
@@ -112,6 +102,16 @@ func init() {
 			childSpan.SetStatus(codes.Ok, "success")
 		}()
 
+		/*
+			### LOGS ###
+		*/
+		loggerProvider := log.NewLoggerProvider(log.WithProcessor(wasiLogs.NewWasiLogProcessor()))
+		logger := loggerProvider.Logger("spin-logs")
+		logRecord := logApi.Record{}
+		logRecord.SetBody(logApi.StringValue("Hello from Go!"))
+		logRecord.SetSeverity(logApi.SeverityInfo)
+		logger.Emit(hostCtx, logRecord) // To have the log associated with the trace, we pass the host context
+
 		w.Header().Set("Content-Type", "text/plain")
 		fmt.Fprintln(w, "Hello World!")
 	})
diff --git a/go/tracing/conversions.go b/go/tracing/conversions.go
index f595546..bb567ac 100644
--- a/go/tracing/conversions.go
+++ b/go/tracing/conversions.go
@@ -3,6 +3,7 @@ package tracing
 import (
 	"encoding/hex"
 	"fmt"
+	"strings"
 
 	"github.com/bytecodealliance/wit-bindgen/wit_types"
 	"github.com/calebschoepp/opentelemetry-wasi/internal/wasi_otel_tracing"
@@ -89,7 +90,9 @@ func toWasiSpanKind(sk traceApi.SpanKind) wasi_otel_tracing.SpanKind {
 }
 
 func toOtelSpanContext(ctx wasi_otel_tracing.SpanContext) traceApi.SpanContext {
-	tid, err := hex.DecodeString(ctx.TraceId)
+	traceIdHex := fmt.Sprintf("%032s", ctx.TraceId)
+	traceIdHex = strings.ReplaceAll(traceIdHex, " ", "0")
+	tid, err := hex.DecodeString(traceIdHex)
 	if err != nil {
 		panic(fmt.Sprintf("invalid trace ID: %v", err))
 	}
@@ -97,7 +100,9 @@ func toOtelSpanContext(ctx wasi_otel_tracing.SpanContext) traceApi.SpanContext {
 		panic(fmt.Sprintf("trace ID must be 16 bytes, got %d", len(tid)))
 	}
 
-	sid, err := hex.DecodeString(ctx.SpanId)
+	spanIdHex := fmt.Sprintf("%016s", ctx.SpanId)
+	spanIdHex = strings.ReplaceAll(spanIdHex, " ", "0")
+	sid, err := hex.DecodeString(spanIdHex)
 	if err != nil {
 		panic(fmt.Sprintf("invalid span ID: %v", err))
 	}
diff --git a/ts/examples/spin-basic/src/index.ts b/ts/examples/spin-basic/src/index.ts
index 0f48aa4..18d8061 100644
--- a/ts/examples/spin-basic/src/index.ts
+++ b/ts/examples/spin-basic/src/index.ts
@@ -36,6 +36,8 @@ const provider = new BasicTracerProvider({
 
 const router = AutoRouter();
 router.get('/', async () => {
+  const hostContext = propagator.extract(context.active());
+
   /*
     ### METRICS ###
   */
@@ -64,16 +66,16 @@ router.get('/', async () => {
 
   const logger = logs.getLogger('spin-logs');
   logger.emit({
-    severityNumber: SeverityNumber.INFO,
-    severityText: 'INFO',
-    body: 'Hello from TypeScript!',
-    attributes: attrs,
-  });
+      severityNumber: SeverityNumber.INFO,
+      severityText: 'INFO',
+      body: 'Hello from TypeScript!',
+      attributes: attrs,
+      context: hostContext, // To have the log associated with the trace, we pass the host context
+    });
 
   /*
     ### TRACING ###
   */
-  const hostContext = propagator.extract(context.active());
   const tracer = provider.getTracer('basic-spin');
   return tracer.startActiveSpan(
     'main-operation',
diff --git a/ts/src/logs.ts b/ts/src/logs.ts
index 18aec43..c22193d 100644
--- a/ts/src/logs.ts
+++ b/ts/src/logs.ts
@@ -4,6 +4,7 @@ import { LogRecord as WasiLogRecord } from 'wasi:otel/logs@0.2.0-rc.2';
 import { KeyValue as WasiKeyValue } from 'wasi:otel/types@0.2.0-rc.2';
 import { dateTimeToWasi, instrumentationScopeToWasi } from './types';
 import { AnyValue, AnyValueMap } from '@opentelemetry/api-logs';
+import { TraceFlags } from '@opentelemetry/api';
 
 export class WasiLogProcessor implements LogRecordProcessor {
   onEmit(logRecord: SdkLogRecord): void {
@@ -38,9 +39,9 @@ function logRecordToWasi(r: SdkLogRecord): WasiLogRecord {
       schemaUrl: r.resource.schemaUrl,
     },
     instrumentationScope: instrumentationScopeToWasi(r.instrumentationScope),
-    traceId: undefined,
-    spanId: undefined,
-    traceFlags: undefined,
+    traceId: r.spanContext?.traceId,
+    spanId: r.spanContext?.spanId,
+    traceFlags: r.spanContext ? { sampled: !!(r.spanContext.traceFlags & TraceFlags.SAMPLED) } : undefined,
   };
 }