Ensure stackdriver labels are respected

Author: nhooyr

sloggers/slogstackdriver/slogstackdriver.go

@@ -27,16 +27,21 @@ type Config struct {
 //
 // See https://cloud.google.com/logging/docs/agent
 func Make(w io.Writer, config *Config) slog.Logger {
+	if config == nil {
+		config = &Config{}
+	}
 	projectID, _ := metadata.ProjectID()
 
 	return slog.Make(stackdriverSink{
 		projectID: projectID,
 		w:         syncwriter.New(w),
+		labels:    config.Labels,
 	})
 }
 
 type stackdriverSink struct {
 	projectID string
+	labels    slog.Map
 	w         *syncwriter.Writer
 }
 
@@ -67,6 +72,10 @@ func (s stackdriverSink) LogEntry(ctx context.Context, ent slog.SinkEntry) error
 		)
 	}
 
+	if len(s.labels) > 0 {
+		e = append(e, slog.F("logging.googleapis.com/labels", s.labels))
+	}
+
 	e = append(e, ent.Fields...)
 
 	buf, _ := json.Marshal(e)

sloggers/slogstackdriver/slogstackdriver_test.go

@@ -24,12 +24,14 @@ func TestStackdriver(t *testing.T) {
 
 	ctx, s := trace.StartSpan(bg, "meow")
 	b := &bytes.Buffer{}
-	l := slogstackdriver.Make(b, nil)
+	l := slogstackdriver.Make(b, &slogstackdriver.Config{
+		Labels: slog.M(slog.F("label", 2)),
+	})
 	l = l.Named("meow")
 	l.Error(ctx, "line1\n\nline2", slog.F("wowow", "me\nyou"))
 
 	j := slogfmt.FilterJSONField(b.String(), "timestamp")
-	exp := fmt.Sprintf(`{"severity":"ERROR","message":"line1\n\nline2","logging.googleapis.com/sourceLocation":"file:\"%v\" line:29 function:\"cdr.dev/slog/sloggers/slogstackdriver_test.TestStackdriver\" ","logging.googleapis.com/operation":"producer:\"meow\" ","logging.googleapis.com/trace":"projects//traces/%v","logging.googleapis.com/spanId":"%v","logging.googleapis.com/trace_sampled":false,"wowow":"me\nyou"}
+	exp := fmt.Sprintf(`{"severity":"ERROR","message":"line1\n\nline2","logging.googleapis.com/sourceLocation":"file:\"%v\" line:31 function:\"cdr.dev/slog/sloggers/slogstackdriver_test.TestStackdriver\" ","logging.googleapis.com/operation":"producer:\"meow\" ","logging.googleapis.com/trace":"projects//traces/%v","logging.googleapis.com/spanId":"%v","logging.googleapis.com/trace_sampled":false,"logging.googleapis.com/labels":{"label":2},"wowow":"me\nyou"}
 `, slogstackdriverTestFile, s.SpanContext().TraceID, s.SpanContext().SpanID)
 	assert.Equal(t, exp, j, "entry")
 }