From b9ccd9c3cbbe39dfd1b74b753f2bbc0c21a0219f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kevin=20Wiesm=C3=BCller?= <kwiesmueller@seibert-media.net>
Date: Fri, 4 Jan 2019 17:52:17 +0100
Subject: [PATCH] add api error for apply conflicts and check in field manager

---
 .../apimachinery/pkg/api/errors/errors.go     | 25 +++++++++++++++++++
 .../handlers/fieldmanager/fieldmanager.go     |  4 +++
 2 files changed, 29 insertions(+)

diff --git a/staging/src/k8s.io/apimachinery/pkg/api/errors/errors.go b/staging/src/k8s.io/apimachinery/pkg/api/errors/errors.go
index e736a986140..73a80d7b4a5 100644
--- a/staging/src/k8s.io/apimachinery/pkg/api/errors/errors.go
+++ b/staging/src/k8s.io/apimachinery/pkg/api/errors/errors.go
@@ -27,6 +27,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/util/validation/field"
+	"sigs.k8s.io/structured-merge-diff/merge"
 )
 
 const (
@@ -184,6 +185,30 @@ func NewConflict(qualifiedResource schema.GroupResource, name string, err error)
 	}}
 }
 
+// NewApplyConflict returns an error including details on the requests apply conflicts
+func NewApplyConflict(conflicts merge.Conflicts, err error) *StatusError {
+	causes := make([]metav1.StatusCause, 0, len(conflicts))
+	for i := range conflicts {
+		err := conflicts[i]
+		causes = append(causes, metav1.StatusCause{
+			Type:    metav1.CauseType("conflict"),
+			Message: err.Error(),
+			Field:   err.Path.String(),
+		})
+	}
+
+	return &StatusError{ErrStatus: metav1.Status{
+		Status: metav1.StatusFailure,
+		Code:   http.StatusConflict,
+		Reason: metav1.StatusReasonConflict,
+		Details: &metav1.StatusDetails{
+			// TODO: Get obj details here?
+			Causes: causes,
+		},
+		Message: fmt.Sprintf("Apply failed with %d conflicts: %v", len(conflicts), err),
+	}}
+}
+
 // NewGone returns an error indicating the item no longer available at the server and no forwarding address is known.
 func NewGone(message string) *StatusError {
 	return &StatusError{metav1.Status{
diff --git a/staging/src/k8s.io/apiserver/pkg/endpoints/handlers/fieldmanager/fieldmanager.go b/staging/src/k8s.io/apiserver/pkg/endpoints/handlers/fieldmanager/fieldmanager.go
index 4b093e70db0..e5846ced5db 100644
--- a/staging/src/k8s.io/apiserver/pkg/endpoints/handlers/fieldmanager/fieldmanager.go
+++ b/staging/src/k8s.io/apiserver/pkg/endpoints/handlers/fieldmanager/fieldmanager.go
@@ -19,6 +19,7 @@ package fieldmanager
 import (
 	"fmt"
 
+	"k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apiserver/pkg/endpoints/handlers/fieldmanager/internal"
@@ -136,6 +137,9 @@ func (f *FieldManager) Apply(liveObj runtime.Object, patch []byte, force bool) (
 	apiVersion := fieldpath.APIVersion(f.groupVersion.String())
 	newObjTyped, managed, err := f.updater.Apply(liveObjTyped, patchObjTyped, apiVersion, managed, applyManager, force)
 	if err != nil {
+		if conflicts, ok := err.(merge.Conflicts); ok {
+			return nil, errors.NewApplyConflict(conflicts, err)
+		}
 		return nil, err
 	}