feat(core): add new GetTraceId function (#3720)

Author: marceljk

CHANGELOG.md

@@ -1,3 +1,7 @@
+## Release (2025-XX-YY)
+- `core`: [v0.20.0](core/CHANGELOG.md#v0200)
+  - **New:** Added new `GetTraceId` function
+
 ## Release (2025-11-14)
 - `core`: 
   - [v0.19.0](core/CHANGELOG.md#v0190)

core/CHANGELOG.md

@@ -1,3 +1,6 @@
+## v0.20.0
+- **New:** Added new `GetTraceId` function
+
 ## v0.19.0
 - **New:** Added new `EnumSliceToStringSlice ` util func
 

core/VERSION

@@ -1 +1 @@
-v0.19.0
+v0.20.0

core/runtime/runtime.go

@@ -7,6 +7,10 @@ import (
 	"github.com/stackitcloud/stackit-sdk-go/core/config"
 )
 
+const (
+	xTraceIdHeader = "x-trace-id"
+)
+
 // WithCaptureHTTPResponse adds the raw HTTP response retrieval annotation to the parent context.
 // The resp parameter will contain the raw HTTP response after the request has completed.
 func WithCaptureHTTPResponse(parent context.Context, resp **http.Response) context.Context {
@@ -18,3 +22,16 @@ func WithCaptureHTTPResponse(parent context.Context, resp **http.Response) conte
 func WithCaptureHTTPRequest(parent context.Context, req **http.Request) context.Context {
 	return context.WithValue(parent, config.ContextHTTPRequest, req)
 }
+
+// GetTraceId returns the X-trace-id from the last response. If no trace-id can be found, it returns an empty string.
+// Prerequisite is, that WithCaptureHTTPResponse was executed before. It reads the X-trace-id header from the
+// attached http response within the context.
+func GetTraceId(ctx context.Context) string {
+	var traceId string
+	if resp, ok := ctx.Value(config.ContextHTTPResponse).(**http.Response); ok {
+		if resp != nil && *resp != nil {
+			traceId = (*resp).Header.Get(xTraceIdHeader)
+		}
+	}
+	return traceId
+}

core/runtime/runtime_test.go

@@ -0,0 +1,75 @@
+package runtime
+
+import (
+	"context"
+	"net/http"
+	"testing"
+)
+
+func TestGetTraceId(t *testing.T) {
+	type args struct {
+		ctx context.Context
+	}
+	tests := []struct {
+		name        string
+		args        args
+		wantTraceId string
+	}{
+		{
+			name: "with set traceId",
+			args: args{
+				ctx: func() context.Context {
+					ctx := context.Background()
+					header := http.Header{}
+					header.Set(xTraceIdHeader, "my-trace-id")
+					httpResp := &http.Response{
+						Header: header,
+					}
+					ctx = WithCaptureHTTPResponse(ctx, &httpResp)
+					return ctx
+				}(),
+			},
+			wantTraceId: "my-trace-id",
+		},
+		{
+			name: "without traceId header",
+			args: args{
+				ctx: func() context.Context {
+					ctx := context.Background()
+					httpResp := &http.Response{
+						Header: http.Header{},
+					}
+					ctx = WithCaptureHTTPResponse(ctx, &httpResp)
+					return ctx
+				}(),
+			},
+			wantTraceId: "",
+		},
+		{
+			name: "with empty response",
+			args: args{
+				ctx: func() context.Context {
+					ctx := context.Background()
+					var httpResp *http.Response
+					ctx = WithCaptureHTTPResponse(ctx, &httpResp)
+					return ctx
+				}(),
+			},
+			wantTraceId: "",
+		},
+		{
+			name: "without response in context",
+			args: args{
+				ctx: context.Background(),
+			},
+			wantTraceId: "",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if gotTraceId := GetTraceId(tt.args.ctx); gotTraceId != tt.wantTraceId {
+				t.Errorf("GetTraceId() = %v, want %v", gotTraceId, tt.wantTraceId)
+			}
+		})
+	}
+}