Accept: application/llm

CHANGELOG.md

@@ -11,6 +11,8 @@
 * [FEATURE] Add query_end_cutoff setting to clamp near-“now” queries (default 30s) for consistent Tempo results [#5682](https://github.com/grafana/tempo/pull/5682) (@javiermolinar)
 * [FEATURE] New block encoding vParquet5-preview4 with array support for dedicated columns. This is a preview, breaking changes are expected. [#5760](https://github.com/grafana/tempo/pull/5760) (@stoewer)
 * [FEATURE] Add SSE-C encryption support to S3 backend [#5789](https://github.com/grafana/tempo/pull/5789) (@steffsas)
+* [FEATURE] Add support for `Accept: application/vnd.grafana.llm` to Tempo endpoints. Currently supported directly by trace by id and tag values [#5961](https://github.com/grafana/tempo/pull/5961) (@joe-elliott)
+  This response is subject to change and should not be relied on. It is intended for LLM consumption only. Even a fundamental change to its representation (yaml? markdown?) would not be considered breaking.
 * [ENHANCEMENT] docs: Add explicit notes about authentication [#5735](https://github.com/grafana/tempo/pull/5735) (@electron0zero)
 * [ENHANCEMENT] On startup, first record for live store to consume is not older than two complete block timeouts [#5693](https://github.com/grafana/tempo/pull/5693) (@ruslan-mikhailov)
 * [ENHANCEMENT] Add secure connection support to tempo-cli [#5692](https://github.com/grafana/tempo/pull/5692) (@TheoBrigitte)

integration/e2e/api/mcp_test.go

@@ -8,12 +8,10 @@ import (
 	"testing"
 	"time"
 
-	"github.com/gogo/protobuf/jsonpb"
 	"github.com/grafana/e2e"
 	e2edb "github.com/grafana/e2e/db"
 	"github.com/grafana/tempo/integration/util"
 	"github.com/grafana/tempo/pkg/api"
-	"github.com/grafana/tempo/pkg/tempopb"
 	tempoUtil "github.com/grafana/tempo/pkg/util"
 	"github.com/stretchr/testify/require"
 
@@ -43,7 +41,7 @@ func TestMCP(t *testing.T) {
 	info := tempoUtil.NewTraceInfo(time.Now(), "")
 	require.NoError(t, info.EmitAllBatches(jaegerClient))
 
-	expected, err := info.ConstructTraceFromEpoch()
+	_, err = info.ConstructTraceFromEpoch()
 	require.NoError(t, err)
 
 	// now query it back with mcp
@@ -84,8 +82,7 @@ func TestMCP(t *testing.T) {
 	sort.Strings(expectedTools)
 	require.Equal(t, expectedTools, actualTools)
 
-	trace := traceOverMCP(t, mcpClient, info.HexID())
-	util.AssertEqualTrace(t, expected, trace)
+	assertTraceOverMCP(t, mcpClient, info.HexID())
 }
 
 func createMCPClient(t *testing.T, tempo *e2e.HTTPService) mcpclient.MCPClient {
@@ -119,7 +116,7 @@ func listTools(t *testing.T, mcpClient mcpclient.MCPClient) []mcp.Tool {
 	return toolsResponse.Tools
 }
 
-func traceOverMCP(t *testing.T, mcpClient mcpclient.MCPClient, traceID string) *tempopb.Trace {
+func assertTraceOverMCP(t *testing.T, mcpClient mcpclient.MCPClient, traceID string) {
 	resp, err := mcpClient.CallTool(context.Background(), mcp.CallToolRequest{
 		Params: mcp.CallToolParams{
 			Name:      "get-trace",
@@ -130,11 +127,10 @@ func traceOverMCP(t *testing.T, mcpClient mcpclient.MCPClient, traceID string) *
 
 	str := toolResult(t, resp)
 
-	trace := &tempopb.TraceByIDResponse{}
-	err = jsonpb.UnmarshalString(str, trace)
-	require.NoError(t, err)
-
-	return trace.Trace
+	// the trace format is subject is to change so let's keep it simple.
+	if !strings.Contains(str, traceID) {
+		t.Fatalf("expected trace ID %s not found in response", traceID)
+	}
 }
 
 func toolResult(t *testing.T, resp *mcp.CallToolResult) string {

modules/frontend/combiner/common.go

@@ -1,11 +1,14 @@
 package combiner
 
 import (
+	"bytes"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
 	"strings"
 	"sync"
+	"unsafe"
 
 	tempo_io "github.com/grafana/tempo/pkg/io"
 	"github.com/grafana/tempo/pkg/tempopb"
@@ -38,7 +41,7 @@ type genericCombiner[T TResponse] struct {
 	combine  func(partial T, final T, resp PipelineResponse) error
 	metadata func(resp PipelineResponse, final T) error
 	finalize func(T) (T, error)
-	diff     func(T) (T, error) // currently only implemented by the search combiner. required for streaming
+	diff     func(T) (T, error)
 	quit     func(T) bool
 
 	// Used to determine the response code and when to stop
@@ -163,27 +166,18 @@ func (c *genericCombiner[T]) HTTPFinal() (*http.Response, error) {
 		return nil, err
 	}
 
-	var bodyString string
-	if c.httpMarshalingFormat == api.MarshallingFormatProtobuf {
-		buff, err := proto.Marshal(final)
-		if err != nil {
-			return nil, fmt.Errorf("error marshalling response body: %w", err)
-		}
-		bodyString = string(buff)
-	} else {
-		bodyString, err = new(jsonpb.Marshaler).MarshalToString(final)
-		if err != nil {
-			return nil, fmt.Errorf("error marshalling response body: %w", err)
-		}
+	bodyBytes, contentType, err := c.internalMarshalAs(final)
+	if err != nil {
+		return nil, fmt.Errorf("error marshalling response body as %s: %w", c.httpMarshalingFormat, err)
 	}
 
 	return &http.Response{
 		StatusCode: 200,
 		Header: http.Header{
-			api.HeaderContentType: {string(c.httpMarshalingFormat)},
+			api.HeaderContentType: {contentType},
 		},
-		Body:          io.NopCloser(strings.NewReader(bodyString)),
-		ContentLength: int64(len([]byte(bodyString))),
+		Body:          io.NopCloser(bytes.NewReader(bodyBytes)),
+		ContentLength: int64(len(bodyBytes)),
 	}, nil
 }
 
@@ -291,6 +285,43 @@ func (c *genericCombiner[R]) shouldQuit() bool {
 	return false
 }
 
+func (c *genericCombiner[T]) internalMarshalAs(final T) ([]byte, string, error) {
+	var bodyBytes []byte
+	var contentType string
+	var err error
+
+	switch c.httpMarshalingFormat {
+	case api.MarshallingFormatProtobuf:
+		bodyBytes, err = proto.Marshal(final)
+		contentType = string(api.MarshallingFormatProtobuf)
+	case api.MarshallingFormatLLM:
+		var bodyString string
+		bodyString, err = new(llmMarshaler).marshalToString(final)
+		contentType = string(api.MarshallingFormatLLM) + "+json" // postfix the content subtype to indicate its parseable as json
+		// if its unsupported, just fallthrough to marshal as normal json
+		if errors.Is(err, util.ErrUnsupported) {
+			bodyString, err = new(jsonpb.Marshaler).MarshalToString(final)
+			contentType = string(api.MarshallingFormatJSON)
+		}
+		bodyBytes = unsafeStringToBytes(bodyString)
+	case api.MarshallingFormatJSON:
+		fallthrough
+	default:
+		var bodyString string
+		bodyString, err = new(jsonpb.Marshaler).MarshalToString(final)
+		contentType = string(api.MarshallingFormatJSON)
+		bodyBytes = unsafeStringToBytes(bodyString)
+	}
+
+	return bodyBytes, contentType, err
+}
+
 type TraceRedactor interface {
 	RedactTraceAttributes(t *tempopb.Trace)
 }
+
+// unsafeStringToBytes converts a string to []byte without allocation.
+// The returned byte slice must not be modified.
+func unsafeStringToBytes(s string) []byte {
+	return unsafe.Slice(unsafe.StringData(s), len(s))
+}