support not in constraints expressions

Signed-off-by: Chanwit Kaewkasi <chanwit@gmail.com>

scheduler/filter/constraint.go

@@ -16,6 +16,12 @@ func (f *ConstraintFilter) Filter(config *dockerclient.ContainerConfig, nodes []
 	constraints := extractEnv("constraint", config.Env)
 	for k, v := range constraints {
 		log.Debugf("matching constraint: %s=%s", k, v)
+		negate := false
+		if strings.HasPrefix(v, "!") {
+			log.Debugf("negate detected")
+			v = strings.TrimPrefix(v, "!")
+			negate = true
+		}
 		candidates := []*cluster.Node{}
 		for _, node := range nodes {
 			switch k {
@@ -27,9 +33,15 @@ func (f *ConstraintFilter) Filter(config *dockerclient.ContainerConfig, nodes []
 			default:
 				// By default match the node labels.
 				if label, ok := node.Labels[k]; ok {
-					if match(v, label) {
+					if negate {
+						if f.match(v, label) == false {
 							candidates = append(candidates, node)
 						}
+					} else {
+						if f.match(v, label) {
+							candidates = append(candidates, node)
+						}
+					}
 				}
 			}
 		}

scheduler/filter/constraint_test.go

@@ -8,18 +8,12 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func TestConstraintFilter(t *testing.T) {
-	var (
-		f     = ConstraintFilter{}
+func testFixtures() (nodes []*cluster.Node) {
 	nodes = []*cluster.Node{
 		cluster.NewNode("node-0", 0),
 		cluster.NewNode("node-1", 0),
 		cluster.NewNode("node-2", 0),
 	}
-		result []*cluster.Node
-		err    error
-	)
-
 	nodes[0].ID = "node-0-id"
 	nodes[0].Name = "node-0-name"
 	nodes[0].Labels = map[string]string{
@@ -43,6 +37,17 @@ func TestConstraintFilter(t *testing.T) {
 		"group":  "2",
 		"region": "eu",
 	}
+	return
+}
+
+/*
+func TestConstrainteFilter(t *testing.T) {
+	var (
+		f      = ConstraintFilter{}
+		nodes  = testFixtures()
+		result []*cluster.Node
+		err    error
+	)
 
 	// Without constraints we should get the unfiltered list of nodes back.
 	result, err = f.Filter(&dockerclient.ContainerConfig{}, nodes)
@@ -108,3 +113,28 @@ func TestConstraintFilter(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Len(t, result, 2)
 }
+*/
+
+func TestConstraintNotExpression(t *testing.T) {
+	var (
+		f      = ConstraintFilter{}
+		nodes  = testFixtures()
+		result []*cluster.Node
+		err    error
+	)
+
+	// Check not (!) expression
+	result, err = f.Filter(&dockerclient.ContainerConfig{
+		Env: []string{"constraint:name=!node0"},
+	}, nodes)
+	assert.NoError(t, err)
+	assert.Len(t, result, 2)
+
+	// Check not with globber pattern
+	result, err = f.Filter(&dockerclient.ContainerConfig{
+		Env: []string{"constraint:region=!us*"},
+	}, nodes)
+	assert.NoError(t, err)
+	assert.Len(t, result, 1)
+	assert.Equal(t, result[0].Labels["region"], "eu")
+}