fix(init): fix REPORT log format and add init timeout retry support

- Move Init Duration after Max Memory Used in REPORT line (matches AWS)
- Add Status: timeout to REPORT line on invoke timeout
- Fix timeout error message format to "RequestId: <id> Error: Task timed out after N.00 seconds"
- Add ErrorType: "Sandbox.Timedout" to timeout error response
- Track init start time and emit Init Duration on first non-retry invocation
- Add is-init-retry field to InvokeRequest to suppress Init Duration on retry invokes

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: joe4dev

cmd/localstack/awsutil.go

@@ -92,7 +92,7 @@ func getBootstrap(args []string) (interop.Bootstrap, string) {
 	return NewSimpleBootstrap(bootstrapLookupCmd, currentWorkingDir), handler
 }
 
-func PrintEndReports(invokeId string, initDuration string, memorySize string, invokeStart time.Time, timeoutDuration time.Duration, w io.Writer) {
+func PrintEndReports(invokeId string, initDuration string, status string, memorySize string, invokeStart time.Time, timeoutDuration time.Duration, w io.Writer) {
 	// Calculate invoke duration
 	invokeDuration := math.Min(float64(time.Now().Sub(invokeStart).Nanoseconds()),
 		float64(timeoutDuration.Nanoseconds())) / float64(time.Millisecond)
@@ -102,11 +102,12 @@ func PrintEndReports(invokeId string, initDuration string, memorySize string, in
 	// not a clean way to get this information from rapidcore
 	_, _ = fmt.Fprintf(w,
 		"REPORT RequestId: %s\t"+
-			initDuration+
 			"Duration: %.2f ms\t"+
 			"Billed Duration: %.f ms\t"+
 			"Memory Size: %s MB\t"+
-			"Max Memory Used: %s MB\t\n",
+			"Max Memory Used: %s MB\t"+
+			initDuration+
+			status+"\n",
 		invokeId, invokeDuration, math.Ceil(invokeDuration), memorySize, memorySize)
 }
 

cmd/localstack/custom_interop.go

@@ -28,6 +28,8 @@ type CustomInteropServer struct {
 	localStackAdapter *LocalStackAdapter
 	port              string
 	upstreamEndpoint  string
+	initStart         time.Time
+	warmStart         bool
 }
 
 type LocalStackAdapter struct {
@@ -113,6 +115,13 @@ func NewCustomInteropServer(lsOpts *LsOpts, delegate interop.Server, logCollecto
 				functionVersion := GetEnvOrDie("AWS_LAMBDA_FUNCTION_VERSION") // default $LATEST
 				_, _ = fmt.Fprintf(logCollector, "START RequestId: %s Version: %s\n", invokeR.InvokeId, functionVersion)
 
+				initDuration := ""
+				if !server.warmStart && !invokeR.IsInitRetry {
+					initTimeMS := float64(time.Since(server.initStart).Nanoseconds()) / float64(time.Millisecond)
+					initDuration = fmt.Sprintf("Init Duration: %.2f ms\t", initTimeMS)
+				}
+				server.warmStart = true
+
 				invokeStart := time.Now()
 				err = server.Invoke(invokeResp, &interop.Invoke{
 					ID:                 invokeR.InvokeId,
@@ -134,15 +143,17 @@ func NewCustomInteropServer(lsOpts *LsOpts, delegate interop.Server, logCollecto
 				})
 				timeout := int(server.delegate.GetInvokeTimeout().Seconds())
 				isErr := false
+				status := ""
 				if err != nil {
 					switch {
 					case errors.Is(err, rapidcore.ErrInvokeTimeout):
 						log.Debugf("Got invoke timeout")
 						isErr = true
+						status = "Status: timeout"
 						errorResponse := lsapi.ErrorResponse{
+							ErrorType: "Sandbox.Timedout",
 							ErrorMessage: fmt.Sprintf(
-								"%s %s Task timed out after %d.00 seconds",
-								time.Now().Format("2006-01-02T15:04:05Z"),
+								"RequestId: %s Error: Task timed out after %d.00 seconds",
 								invokeR.InvokeId,
 								timeout,
 							),
@@ -171,7 +182,7 @@ func NewCustomInteropServer(lsOpts *LsOpts, delegate interop.Server, logCollecto
 				}
 				timeoutDuration := time.Duration(timeout) * time.Second
 				memorySize := GetEnvOrDie("AWS_LAMBDA_FUNCTION_MEMORY_SIZE")
-				PrintEndReports(invokeR.InvokeId, "", memorySize, invokeStart, timeoutDuration, logCollector)
+				PrintEndReports(invokeR.InvokeId, initDuration, status, memorySize, invokeStart, timeoutDuration, logCollector)
 
 				if err2 := server.localStackAdapter.SendLogs(invokeR.InvokeId, logCollector.getLogs()); err2 != nil {
 					log.Error("failed to send logs to LocalStack: ", err2)
@@ -258,6 +269,7 @@ func (c *CustomInteropServer) SendRuntimeReady() error {
 
 func (c *CustomInteropServer) Init(i *interop.Init, invokeTimeoutMs int64) error {
 	log.Traceln("Init called")
+	c.initStart = time.Now()
 	return c.delegate.Init(i, invokeTimeoutMs)
 }
 

internal/lsapi/types.go

@@ -6,6 +6,7 @@ type InvokeRequest struct {
 	InvokedFunctionArn string `json:"invoked-function-arn"`
 	Payload            string `json:"payload"`
 	TraceId            string `json:"trace-id"`
+	IsInitRetry        bool   `json:"is-init-retry,omitempty"`
 }
 
 // LogResponse is sent by the runtime to report logs for a completed invocation.