Validate method, and rename ratio field to percent

nomad/structs/structs.go

@@ -5401,9 +5401,9 @@ type Spread struct {
 }
 
 type SpreadTarget struct {
-	Value string
-	Ratio uint32
-	str   string
+	Value   string
+	Percent uint32
+	str     string
 }
 
 func (s *Spread) Copy() *Spread {
@@ -5439,10 +5439,36 @@ func (s *SpreadTarget) String() string {
 	if s.str != "" {
 		return s.str
 	}
-	s.str = fmt.Sprintf("%s %v", s.Value, s.Ratio)
+	s.str = fmt.Sprintf("%s %v", s.Value, s.Percent)
 	return s.str
 }
 
+func (s *Spread) Validate() error {
+	var mErr multierror.Error
+	if s.Attribute == "" {
+		mErr.Errors = append(mErr.Errors, errors.New("Missing spread attribute"))
+	}
+	if s.Weight <= 0 || s.Weight > 100 {
+		mErr.Errors = append(mErr.Errors, errors.New("Spread stanza must have a positive weight from 0 to 100"))
+	}
+	if len(s.SpreadTarget) == 0 {
+		// TODO(preetha): This should go away if we can assume even spread if there are no targets
+		// In that case, the target percentages should be calculated at schedule time
+		mErr.Errors = append(mErr.Errors, errors.New("Atleast one spread target value must be specified"))
+	}
+	seen := make(map[string]struct{})
+	for _, target := range s.SpreadTarget {
+		// Make sure there are no duplicates
+		_, ok := seen[target.Value]
+		if !ok {
+			seen[target.Value] = struct{}{}
+		} else {
+			mErr.Errors = append(mErr.Errors, errors.New(fmt.Sprintf("Spread target value %q already defined", target.Value)))
+		}
+	}
+	return mErr.ErrorOrNil()
+}
+
 // EphemeralDisk is an ephemeral disk object
 type EphemeralDisk struct {
 	// Sticky indicates whether the allocation is sticky to a node

nomad/structs/structs_test.go

@@ -3926,3 +3926,91 @@ func TestNode_Copy(t *testing.T) {
 	require.Equal(node.DrainStrategy, node2.DrainStrategy)
 	require.Equal(node.Drivers, node2.Drivers)
 }
+
+func TestSpread_Validate(t *testing.T) {
+	type tc struct {
+		spread *Spread
+		err    error
+		name   string
+	}
+
+	testCases := []tc{
+		{
+			spread: &Spread{},
+			err:    fmt.Errorf("Missing spread attribute"),
+			name:   "empty spread",
+		},
+		{
+			spread: &Spread{
+				Attribute: "${node.datacenter}",
+				Weight:    -1,
+			},
+			err:  fmt.Errorf("Spread stanza must have a positive weight from 0 to 100"),
+			name: "Invalid weight",
+		},
+		{
+			spread: &Spread{
+				Attribute: "${node.datacenter}",
+				Weight:    200,
+			},
+			err:  fmt.Errorf("Spread stanza must have a positive weight from 0 to 100"),
+			name: "Invalid weight",
+		},
+		{
+			spread: &Spread{
+				Attribute: "${node.datacenter}",
+				Weight:    50,
+			},
+			err:  fmt.Errorf("Atleast one spread target value must be specified"),
+			name: "No spread targets",
+		},
+		{
+			spread: &Spread{
+				Attribute: "${node.datacenter}",
+				Weight:    50,
+				SpreadTarget: []*SpreadTarget{
+					{
+						Value:   "dc1",
+						Percent: 25,
+					},
+					{
+						Value:   "dc1",
+						Percent: 50,
+					},
+				},
+			},
+			err:  fmt.Errorf("Spread target value \"dc1\" already defined"),
+			name: "No spread targets",
+		},
+		{
+			spread: &Spread{
+				Attribute: "${node.datacenter}",
+				Weight:    50,
+				SpreadTarget: []*SpreadTarget{
+					{
+						Value:   "dc1",
+						Percent: 25,
+					},
+					{
+						Value:   "dc2",
+						Percent: 50,
+					},
+				},
+			},
+			err:  nil,
+			name: "Valid spread",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			err := tc.spread.Validate()
+			if tc.err != nil {
+				require.NotNil(t, err)
+				require.Contains(t, err.Error(), tc.err.Error())
+			} else {
+				require.Nil(t, err)
+			}
+		})
+	}
+}