feat: game lobby service

lobby/internal/logging/context.go

@@ -0,0 +1,43 @@
+package logging
+
+import "context"
+
+// requestIDKey is the unexported context key under which the HTTP layer
+// stores the request id propagated from the X-Request-Id header.
+type requestIDKey struct{}
+
+// WithRequestID returns a child context that carries requestID. An empty
+// requestID returns ctx unchanged so callers do not have to branch.
+func WithRequestID(ctx context.Context, requestID string) context.Context {
+	if ctx == nil || requestID == "" {
+		return ctx
+	}
+	return context.WithValue(ctx, requestIDKey{}, requestID)
+}
+
+// RequestIDFromContext returns the request id stored on ctx by
+// WithRequestID, or an empty string when no value is present.
+func RequestIDFromContext(ctx context.Context) string {
+	if ctx == nil {
+		return ""
+	}
+	value, _ := ctx.Value(requestIDKey{}).(string)
+	return value
+}
+
+// ContextAttrs returns slog key-value pairs that materialise the frozen
+// `lobby/README.md` §Observability log fields `request_id`, `trace_id`,
+// and `span_id` from ctx. Pairs whose value is empty are omitted so logs
+// stay tight.
+func ContextAttrs(ctx context.Context) []any {
+	if ctx == nil {
+		return nil
+	}
+
+	var attrs []any
+	if requestID := RequestIDFromContext(ctx); requestID != "" {
+		attrs = append(attrs, "request_id", requestID)
+	}
+	attrs = append(attrs, TraceAttrsFromContext(ctx)...)
+	return attrs
+}

lobby/internal/logging/context_test.go

@@ -0,0 +1,63 @@
+package logging_test
+
+import (
+	"context"
+	"testing"
+
+	"galaxy/lobby/internal/logging"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"go.opentelemetry.io/otel/trace"
+)
+
+func TestRequestIDRoundTrip(t *testing.T) {
+	t.Parallel()
+
+	ctx := logging.WithRequestID(context.Background(), "rid-1")
+	assert.Equal(t, "rid-1", logging.RequestIDFromContext(ctx))
+
+	assert.Equal(t, "", logging.RequestIDFromContext(context.Background()))
+}
+
+func TestWithRequestIDIgnoresEmptyValue(t *testing.T) {
+	t.Parallel()
+
+	parent := context.Background()
+	ctx := logging.WithRequestID(parent, "")
+	assert.Equal(t, parent, ctx)
+}
+
+func TestContextAttrsIncludesRequestID(t *testing.T) {
+	t.Parallel()
+
+	ctx := logging.WithRequestID(context.Background(), "rid-2")
+	attrs := logging.ContextAttrs(ctx)
+	require.Contains(t, attrs, "request_id")
+	require.Contains(t, attrs, "rid-2")
+}
+
+func TestContextAttrsIncludesTraceID(t *testing.T) {
+	t.Parallel()
+
+	traceID, err := trace.TraceIDFromHex("0123456789abcdef0123456789abcdef")
+	require.NoError(t, err)
+	spanID, err := trace.SpanIDFromHex("fedcba9876543210")
+	require.NoError(t, err)
+	spanContext := trace.NewSpanContext(trace.SpanContextConfig{
+		TraceID: traceID,
+		SpanID:  spanID,
+	})
+	ctx := trace.ContextWithSpanContext(context.Background(), spanContext)
+
+	attrs := logging.ContextAttrs(ctx)
+	require.Contains(t, attrs, "trace_id")
+	require.Contains(t, attrs, traceID.String())
+	require.Contains(t, attrs, "span_id")
+	require.Contains(t, attrs, spanID.String())
+}
+
+func TestContextAttrsEmptyContextReturnsNil(t *testing.T) {
+	t.Parallel()
+	assert.Nil(t, logging.ContextAttrs(context.Background()))
+}

lobby/internal/logging/logger.go

@@ -0,0 +1,45 @@
+// Package logging configures the Game Lobby Service process logger and
+// provides context-aware helpers for trace fields.
+package logging
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"os"
+	"strings"
+
+	"go.opentelemetry.io/otel/trace"
+)
+
+// New constructs the process-wide JSON logger from level.
+func New(level string) (*slog.Logger, error) {
+	var slogLevel slog.Level
+	if err := slogLevel.UnmarshalText([]byte(strings.TrimSpace(level))); err != nil {
+		return nil, fmt.Errorf("build logger: %w", err)
+	}
+
+	return slog.New(slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{
+		Level: slogLevel,
+	})), nil
+}
+
+// TraceAttrsFromContext returns slog key-value pairs for the active
+// OpenTelemetry span when ctx carries a valid span context. The keys match
+// the frozen `lobby/README.md` §Observability log fields `trace_id` and
+// `span_id`.
+func TraceAttrsFromContext(ctx context.Context) []any {
+	if ctx == nil {
+		return nil
+	}
+
+	spanContext := trace.SpanContextFromContext(ctx)
+	if !spanContext.IsValid() {
+		return nil
+	}
+
+	return []any{
+		"trace_id", spanContext.TraceID().String(),
+		"span_id", spanContext.SpanID().String(),
+	}
+}