Fix diff alignment and remove no change DC

command/plan.go

@@ -353,15 +353,17 @@ func formatTaskDiff(task *api.TaskDiff, startPrefix, taskPrefix int, verbose boo
 // of spaces to put between the marker and object name output.
 func formatObjectDiff(diff *api.ObjectDiff, startPrefix, keyPrefix int) string {
 	start := strings.Repeat(" ", startPrefix)
-	marker, _ := getDiffString(diff.Type)
+	marker, markerLen := getDiffString(diff.Type)
 	out := fmt.Sprintf("%s%s%s%s {\n", start, marker, strings.Repeat(" ", keyPrefix), diff.Name)
 
 	// Determine the length of the longest name and longest diff marker to
 	// properly align names and values
 	longestField, longestMarker := getLongestPrefixes(diff.Fields, diff.Objects)
-	subStartPrefix := startPrefix + 2
+	subStartPrefix := startPrefix + keyPrefix + 2
 	out += alignedFieldAndObjects(diff.Fields, diff.Objects, subStartPrefix, longestField, longestMarker)
-	return fmt.Sprintf("%s\n%s}", out, start)
+
+	endprefix := strings.Repeat(" ", startPrefix+markerLen+keyPrefix)
+	return fmt.Sprintf("%s\n%s}", out, endprefix)
 }
 
 // formatFieldDiff produces an annotated diff of a field. startPrefix is the

nomad/structs/diff.go

@@ -98,7 +98,7 @@ func (j *Job) Diff(other *Job, contextual bool) (*JobDiff, error) {
 	diff.Fields = fieldDiffs(oldPrimitiveFlat, newPrimitiveFlat, false)
 
 	// Datacenters diff
-	if setDiff := stringSetDiff(j.Datacenters, other.Datacenters, "Datacenters", contextual); setDiff != nil {
+	if setDiff := stringSetDiff(j.Datacenters, other.Datacenters, "Datacenters", contextual); setDiff != nil && setDiff.Type != DiffTypeNone {
 		diff.Objects = append(diff.Objects, setDiff)
 	}
 

nomad/structs/diff_test.go

@@ -397,7 +397,7 @@ func TestJobDiff(t *testing.T) {
 			},
 		},
 		{
-			// Datacenter contextual
+			// Datacenter contextual no change
 			Contextual: true,
 			Old: &Job{
 				Datacenters: []string{"foo", "bar"},
@@ -407,11 +407,30 @@ func TestJobDiff(t *testing.T) {
 			},
 			Expected: &JobDiff{
 				Type: DiffTypeNone,
+			},
+		},
+		{
+			// Datacenter contextual
+			Contextual: true,
+			Old: &Job{
+				Datacenters: []string{"foo", "bar"},
+			},
+			New: &Job{
+				Datacenters: []string{"foo", "bar", "baz"},
+			},
+			Expected: &JobDiff{
+				Type: DiffTypeEdited,
 				Objects: []*ObjectDiff{
 					{
-						Type: DiffTypeNone,
+						Type: DiffTypeAdded,
 						Name: "Datacenters",
 						Fields: []*FieldDiff{
+							{
+								Type: DiffTypeAdded,
+								Name: "Datacenters",
+								Old:  "",
+								New:  "baz",
+							},
 							{
 								Type: DiffTypeNone,
 								Name: "Datacenters",