fix(init): read LOCALSTACK_INIT_PHASE_TIMEOUT via InitLsOpts and unset it

Follow the established LocalStack-env strategy: capture the value in InitLsOpts
(before UnsetLsEnvs runs) and add it to the UnsetLsEnvs list. Previously it was
read inline with os.Getenv after UnsetLsEnvs, so the variable was never unset and
leaked into the function's environment (forwarded via os.Environ in InitHandler),
breaking AWS parity.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: joe4dev

cmd/localstack/main.go

@@ -43,6 +43,7 @@ type LsOpts struct {
 	EnableXRayTelemetry string
 	PostInvokeWaitMS    string
 	MaxPayloadSize      string
+	InitPhaseTimeout    string
 }
 
 func GetEnvOrDie(env string) string {
@@ -60,12 +61,13 @@ func InitLsOpts() *LsOpts {
 		RuntimeId:       GetEnvOrDie("LOCALSTACK_RUNTIME_ID"),
 		AccountId:       GetenvWithDefault("LOCALSTACK_FUNCTION_ACCOUNT_ID", "000000000000"),
 		// optional with default
-		InteropPort:     GetenvWithDefault("LOCALSTACK_INTEROP_PORT", "9563"),
-		InitTracingPort: GetenvWithDefault("LOCALSTACK_RUNTIME_TRACING_PORT", "9564"),
-		User:            GetenvWithDefault("LOCALSTACK_USER", "sbx_user1051"),
-		InitLogLevel:    GetenvWithDefault("LOCALSTACK_INIT_LOG_LEVEL", "warn"),
-		EdgePort:        GetenvWithDefault("EDGE_PORT", "4566"),
-		MaxPayloadSize:  GetenvWithDefault("LOCALSTACK_MAX_PAYLOAD_SIZE", "6291556"),
+		InteropPort:      GetenvWithDefault("LOCALSTACK_INTEROP_PORT", "9563"),
+		InitTracingPort:  GetenvWithDefault("LOCALSTACK_RUNTIME_TRACING_PORT", "9564"),
+		User:             GetenvWithDefault("LOCALSTACK_USER", "sbx_user1051"),
+		InitLogLevel:     GetenvWithDefault("LOCALSTACK_INIT_LOG_LEVEL", "warn"),
+		EdgePort:         GetenvWithDefault("EDGE_PORT", "4566"),
+		MaxPayloadSize:   GetenvWithDefault("LOCALSTACK_MAX_PAYLOAD_SIZE", "6291556"),
+		InitPhaseTimeout: GetenvWithDefault("LOCALSTACK_INIT_PHASE_TIMEOUT", strconv.Itoa(defaultInitPhaseTimeoutSeconds)),
 		// optional or empty
 		CodeArchives:        os.Getenv("LOCALSTACK_CODE_ARCHIVES"),
 		HotReloadingPaths:   strings.Split(GetenvWithDefault("LOCALSTACK_HOT_RELOADING_PATHS", ""), ","),
@@ -93,6 +95,7 @@ func UnsetLsEnvs() {
 		"LOCALSTACK_POST_INVOKE_WAIT_MS",
 		"LOCALSTACK_FUNCTION_ACCOUNT_ID",
 		"LOCALSTACK_MAX_PAYLOAD_SIZE",
+		"LOCALSTACK_INIT_PHASE_TIMEOUT",
 		"LOCALSTACK_CHMOD_PATHS",
 
 		// Docker container ID
@@ -271,12 +274,10 @@ func main() {
 	InitHandler(sandbox.LambdaInvokeAPI(), GetEnvOrDie("AWS_LAMBDA_FUNCTION_VERSION"), int64(invokeTimeoutSeconds), bootstrap, lsOpts.AccountId) // TODO: replace this with a custom init
 
 	initPhaseTimeoutSeconds := defaultInitPhaseTimeoutSeconds
-	if v := os.Getenv("LOCALSTACK_INIT_PHASE_TIMEOUT"); v != "" {
-		if parsed, perr := strconv.Atoi(v); perr == nil {
-			initPhaseTimeoutSeconds = parsed
-		} else {
-			log.Warnln("Invalid LOCALSTACK_INIT_PHASE_TIMEOUT, using default:", perr)
-		}
+	if parsed, perr := strconv.Atoi(lsOpts.InitPhaseTimeout); perr == nil {
+		initPhaseTimeoutSeconds = parsed
+	} else {
+		log.Warnln("Invalid LOCALSTACK_INIT_PHASE_TIMEOUT, using default:", perr)
 	}
 
 	log.Debugln("Awaiting initialization of runtime init.")