From d7e41330409e18b8de5eefc189ee8171095a50bc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Roland=20Hu=C3=9F?= <roland@ro14nd.de>
Date: Mon, 8 Jul 2019 10:00:45 +0200
Subject: [PATCH] fix(service update): Retry an update in case of a conflict.

Is related to #224 and should fix one flake.
---
 pkg/kn/commands/service/service.go        |  5 +++
 pkg/kn/commands/service/service_create.go | 30 ++++++++++------
 pkg/kn/commands/service/service_update.go | 43 ++++++++++++++---------
 3 files changed, 52 insertions(+), 26 deletions(-)

diff --git a/pkg/kn/commands/service/service.go b/pkg/kn/commands/service/service.go
index 7a4ff8ef2a..9f719a9399 100644
--- a/pkg/kn/commands/service/service.go
+++ b/pkg/kn/commands/service/service.go
@@ -19,6 +19,11 @@ import (
 	"github.com/spf13/cobra"
 )
 
+const (
+	// How often to retry in case of an optimistic lock error when replacing a service (--force)
+	MaxUpdateRetries = 3
+)
+
 func NewServiceCommand(p *commands.KnParams) *cobra.Command {
 	serviceCmd := &cobra.Command{
 		Use:   "service",
diff --git a/pkg/kn/commands/service/service_create.go b/pkg/kn/commands/service/service_create.go
index ba0f885031..1937c71a7e 100644
--- a/pkg/kn/commands/service/service_create.go
+++ b/pkg/kn/commands/service/service_create.go
@@ -131,17 +131,27 @@ func createService(client serving_v1alpha1_client.ServingV1alpha1Interface, serv
 }
 
 func replaceService(client serving_v1alpha1_client.ServingV1alpha1Interface, service *serving_v1alpha1_api.Service, namespace string, out io.Writer) error {
-	existingService, err := client.Services(namespace).Get(service.Name, v1.GetOptions{})
-	if err != nil {
-		return err
-	}
-	service.ResourceVersion = existingService.ResourceVersion
-	_, err = client.Services(namespace).Update(service)
-	if err != nil {
-		return err
+	var retries = 0
+	for true {
+		existingService, err := client.Services(namespace).Get(service.Name, v1.GetOptions{})
+		if err != nil {
+			return err
+		}
+		service.ResourceVersion = existingService.ResourceVersion
+		_, err = client.Services(namespace).Update(service)
+		if err != nil {
+			// Retry to update when a resource version conflict exists
+			if api_errors.IsConflict(err) && retries < MaxUpdateRetries {
+				retries++
+				continue
+			}
+			return err
+		}
+		fmt.Fprintf(out, "Service '%s' successfully replaced in namespace '%s'.\n", service.Name, namespace)
+		return nil
 	}
-	fmt.Fprintf(out, "Service '%s' successfully replaced in namespace '%s'.\n", service.Name, namespace)
-	return nil
+	// This line will be never reached, but go insists on having it
+	return fmt.Errorf("can not update service '%s' in namespace '%s'", service.Name, namespace)
 }
 
 func serviceExists(client serving_v1alpha1_client.ServingV1alpha1Interface, name string, namespace string) (bool, error) {
diff --git a/pkg/kn/commands/service/service_update.go b/pkg/kn/commands/service/service_update.go
index e485bdb646..51ffe092a5 100644
--- a/pkg/kn/commands/service/service_update.go
+++ b/pkg/kn/commands/service/service_update.go
@@ -18,9 +18,11 @@ import (
 	"errors"
 	"fmt"
 
-	"github.com/knative/client/pkg/kn/commands"
 	"github.com/spf13/cobra"
+	api_errors "k8s.io/apimachinery/pkg/api/errors"
 	v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+
+	"github.com/knative/client/pkg/kn/commands"
 )
 
 func NewServiceUpdateCommand(p *commands.KnParams) *cobra.Command {
@@ -53,24 +55,33 @@ func NewServiceUpdateCommand(p *commands.KnParams) *cobra.Command {
 				return err
 			}
 
-			service, err := client.Services(namespace).Get(args[0], v1.GetOptions{})
-			if err != nil {
-				return err
-			}
-			service = service.DeepCopy()
+			var retries = 0
+			for true {
+				service, err := client.Services(namespace).Get(args[0], v1.GetOptions{})
+				if err != nil {
+					return err
+				}
+				service = service.DeepCopy()
 
-			err = editFlags.Apply(service, cmd)
-			if err != nil {
-				return err
-			}
+				err = editFlags.Apply(service, cmd)
+				if err != nil {
+					return err
+				}
 
-			_, err = client.Services(namespace).Update(service)
-			if err != nil {
-				return err
+				_, err = client.Services(namespace).Update(service)
+				if err != nil {
+					// Retry to update when a resource version conflict exists
+					if api_errors.IsConflict(err) && retries < MaxUpdateRetries {
+						retries++
+						continue
+					}
+					return err
+				}
+				fmt.Fprintf(cmd.OutOrStdout(), "Service '%s' updated in namespace '%s'.\n", args[0], namespace)
+				return nil
 			}
-
-			fmt.Fprintf(cmd.OutOrStdout(), "Service '%s' updated in namespace '%s'.\n", args[0], namespace)
-			return nil
+			// This line will be never reached, but go insists on having it
+			return fmt.Errorf("can not update service '%s' in namespace '%s'", args[0], namespace)
 		},
 	}