Enhance googleapi error handling

mysql/provider.go

@@ -13,7 +13,9 @@ import (
 	"time"
 
 	"github.com/go-sql-driver/mysql"
+	"github.com/hashicorp/errwrap"
 	"github.com/hashicorp/go-version"
+	"google.golang.org/api/googleapi"
 
 	"github.com/hashicorp/terraform-plugin-sdk/v2/diag"
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/resource"
@@ -312,15 +314,15 @@ func connectToMySQLInternal(ctx context.Context, conf *MySQLConfiguration) (*One
 	retryError := resource.RetryContext(ctx, conf.ConnectRetryTimeoutSec, func() *resource.RetryError {
 		db, err = sql.Open(driverName, dsn)
 		if err != nil {
-			if mysqlErrorNumber(err) == unknownVarErrCode || ctx.Err() != nil {
+			if mysqlErrorNumber(err) == unknownVarErrCode || cloudsqlErrorNumber(err) != 0 || ctx.Err() != nil {
 				return resource.NonRetryableError(err)
 			}
 			return resource.RetryableError(err)
 		}
 
 		err = db.PingContext(ctx)
 		if err != nil {
-			if mysqlErrorNumber(err) == unknownVarErrCode || ctx.Err() != nil {
+			if mysqlErrorNumber(err) == unknownVarErrCode || cloudsqlErrorNumber(err) != 0 || ctx.Err() != nil {
 				return resource.NonRetryableError(err)
 			}
 
@@ -359,3 +361,20 @@ func mysqlErrorNumber(err error) uint16 {
 	}
 	return me.Number
 }
+
+func cloudsqlErrorNumber(err error) int {
+	if err == nil {
+		return 0
+	}
+
+	if e, ok := err.(*googleapi.Error); ok {
+		return e.Code
+	} else if !ok && errwrap.ContainsType(err, &googleapi.Error{}) {
+		e := errwrap.GetType(err, &googleapi.Error{}).(*googleapi.Error)
+		if e.Code >= 400 && e.Code < 500 {
+			return e.Code
+		}
+	}
+
+	return 0
+}