Use the correct format for the message timestamp

encoder.go

@@ -1,6 +1,10 @@
 package zapdriver
 
-import "go.uber.org/zap/zapcore"
+import (
+	"time"
+
+	"go.uber.org/zap/zapcore"
+)
 
 // logLevelSeverity maps the Zap log levels to the correct level names as
 // defined by Stackdriver.
@@ -37,7 +41,7 @@ var encoderConfig = zapcore.EncoderConfig{
 	StacktraceKey:  "stacktrace",
 	LineEnding:     zapcore.DefaultLineEnding,
 	EncodeLevel:    EncodeLevel,
-	EncodeTime:     zapcore.ISO8601TimeEncoder,
+	EncodeTime:     RFC3339NanoTimeEncoder,
 	EncodeDuration: zapcore.SecondsDurationEncoder,
 	EncodeCaller:   zapcore.ShortCallerEncoder,
 }
@@ -47,3 +51,9 @@ var encoderConfig = zapcore.EncoderConfig{
 func EncodeLevel(l zapcore.Level, enc zapcore.PrimitiveArrayEncoder) {
 	enc.AppendString(logLevelSeverity[l])
 }
+
+// RFC3339NanoTimeEncoder serializes a time.Time to an RFC3339Nano-formatted
+// string with nanoseconds precision.
+func RFC3339NanoTimeEncoder(t time.Time, enc zapcore.PrimitiveArrayEncoder) {
+	enc.AppendString(t.Format(time.RFC3339Nano))
+}

encoder_test.go

@@ -2,6 +2,7 @@ package zapdriver_test
 
 import (
 	"testing"
+	"time"
 
 	"github.com/blendle/zapdriver"
 	"github.com/stretchr/testify/assert"
@@ -35,3 +36,15 @@ func TestEncodeLevel(t *testing.T) {
 		})
 	}
 }
+
+func TestRFC3339NanoTimeEncoder(t *testing.T) {
+	t.Parallel()
+
+	ts := time.Date(2018, 4, 9, 12, 43, 12, 678359, time.UTC)
+
+	enc := &sliceArrayEncoder{}
+	zapdriver.RFC3339NanoTimeEncoder(ts, enc)
+
+	require.Len(t, enc.elems, 1)
+	assert.Equal(t, ts.Format(time.RFC3339Nano), enc.elems[0].(string))
+}