feat: add Kuknos submission observability

infrastructure/kuknos/submitter.go

@@ -4,13 +4,22 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"io"
+	"log/slog"
 	"net/http"
 	"net/url"
 	"strings"
+	"time"
 
 	"gl/domain/ledger"
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/codes"
+	"go.opentelemetry.io/otel/trace"
 )
 
+var tracer = otel.Tracer("gl/infrastructure/kuknos")
+
 // Submitter sends a pre-signed Stellar/Kuknos transaction to Horizon. Signing
 // remains outside GL; GL owns durable admission, retry, and reconciliation.
 type Submitter struct {
@@ -19,25 +28,51 @@ type Submitter struct {
 }
 
 func (s Submitter) Submit(ctx context.Context, record ledger.Settlement) (string, error) {
+	ctx, span := tracer.Start(ctx, "kuknos.submit_transaction", trace.WithSpanKind(trace.SpanKindClient))
+	defer span.End()
+	span.SetAttributes(
+		attribute.String("kuknos.network", record.Network),
+		attribute.String("settlement.id", record.ID),
+		attribute.String("settlement.source_service", record.SourceService),
+		attribute.String("settlement.source_transaction_id", record.SourceTxID),
+		attribute.String("settlement.idempotency_key", record.IdempotencyKey),
+		attribute.Int("settlement.attempt", record.Attempts),
+	)
+
 	if s.Endpoint == "" || record.SignedTransactionXDR == "" {
-		return "", fmt.Errorf("kuknos submission endpoint and signed xdr are required")
+		return s.fail(ctx, span, record, fmt.Errorf("kuknos submission endpoint and signed xdr are required"))
 	}
+	endpoint := strings.TrimRight(s.Endpoint, "/") + "/transactions"
 	form := url.Values{"tx": {record.SignedTransactionXDR}}
-	req, err := http.NewRequestWithContext(ctx, http.MethodPost, strings.TrimRight(s.Endpoint, "/")+"/transactions", strings.NewReader(form.Encode()))
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, endpoint, strings.NewReader(form.Encode()))
 	if err != nil {
-		return "", err
+		return s.fail(ctx, span, record, err)
 	}
 	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
 	client := s.Client
 	if client == nil {
 		client = http.DefaultClient
 	}
+	startedAt := time.Now()
+	slog.InfoContext(ctx, "kuknos transaction submission started",
+		"settlement_id", record.ID,
+		"source_transaction_id", record.SourceTxID,
+		"idempotency_key", record.IdempotencyKey,
+		"network", record.Network,
+		"attempt", record.Attempts,
+		"endpoint", endpoint,
+	)
 	resp, err := client.Do(req)
 	if err != nil {
-		return "", err
+		return s.fail(ctx, span, record, err)
 	}
 	defer resp.Body.Close()
-	var body struct {
+	responseBody, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return s.fail(ctx, span, record, fmt.Errorf("read kuknos response: %w", err))
+	}
+	rawResponse := string(responseBody)
+	var response struct {
 		Hash   string `json:"hash"`
 		Extras struct {
 			ResultCodes struct {
@@ -45,11 +80,60 @@ func (s Submitter) Submit(ctx context.Context, record ledger.Settlement) (string
 			} `json:"result_codes"`
 		} `json:"extras"`
 	}
-	if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {
-		return "", fmt.Errorf("decode kuknos response: %w", err)
+	if err := json.Unmarshal(responseBody, &response); err != nil {
+		slog.ErrorContext(ctx, "kuknos transaction submission returned an invalid response",
+			"settlement_id", record.ID,
+			"source_transaction_id", record.SourceTxID,
+			"idempotency_key", record.IdempotencyKey,
+			"network", record.Network,
+			"attempt", record.Attempts,
+			"status_code", resp.StatusCode,
+			"stellar_response", rawResponse,
+			"error", err,
+		)
+		return s.fail(ctx, span, record, fmt.Errorf("decode kuknos response: %w", err))
 	}
-	if resp.StatusCode < 200 || resp.StatusCode >= 300 || body.Hash == "" {
-		return "", fmt.Errorf("kuknos rejected transaction: status=%d code=%s", resp.StatusCode, body.Extras.ResultCodes.Transaction)
+	latency := time.Since(startedAt)
+	span.SetAttributes(
+		attribute.Int("http.response.status_code", resp.StatusCode),
+		attribute.Int64("http.response.body.size", int64(len(responseBody))),
+		attribute.Int64("kuknos.submission.duration_ms", latency.Milliseconds()),
+	)
+	span.AddEvent("kuknos.response", trace.WithAttributes(
+		attribute.String("stellar_response", rawResponse),
+	))
+	span.SetStatus(codes.Ok, "submission response received")
+	slog.InfoContext(ctx, "kuknos transaction submission response",
+		"settlement_id", record.ID,
+		"source_transaction_id", record.SourceTxID,
+		"idempotency_key", record.IdempotencyKey,
+		"network", record.Network,
+		"attempt", record.Attempts,
+		"status_code", resp.StatusCode,
+		"transaction_hash", response.Hash,
+		"transaction_result_code", response.Extras.ResultCodes.Transaction,
+		"stellar_response", rawResponse,
+		"duration_ms", latency.Milliseconds(),
+	)
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 || response.Hash == "" {
+		err := fmt.Errorf("kuknos rejected transaction: status=%d code=%s", resp.StatusCode, response.Extras.ResultCodes.Transaction)
+		span.SetStatus(codes.Error, err.Error())
+		span.RecordError(err)
+		return "", err
 	}
-	return body.Hash, nil
+	return response.Hash, nil
+}
+
+func (s Submitter) fail(ctx context.Context, span trace.Span, record ledger.Settlement, err error) (string, error) {
+	span.SetStatus(codes.Error, err.Error())
+	span.RecordError(err)
+	slog.ErrorContext(ctx, "kuknos transaction submission failed",
+		"settlement_id", record.ID,
+		"source_transaction_id", record.SourceTxID,
+		"idempotency_key", record.IdempotencyKey,
+		"network", record.Network,
+		"attempt", record.Attempts,
+		"error", err,
+	)
+	return "", err
 }