implement alternative negation syntax

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

scheduler/filter/constraint.go

@@ -45,12 +45,17 @@ func (f *ConstraintFilter) Filter(config *dockerclient.ContainerConfig, nodes []
 
 		// keep the original for display in case of error
 		v0 := v
+		k0 := k
 
 		negate := false
 		if strings.HasPrefix(v, "!") {
-			log.Debugf("negate detected")
+			log.Debugf("negate detected in value")
 			v = strings.TrimPrefix(v, "!")
 			negate = true
+		} else if strings.HasSuffix(k, "!") {
+			log.Debugf("negate detected in key")
+			k = strings.TrimSuffix(k, "!")
+			negate = true
 		}
 
 		useRegex := false
@@ -84,7 +89,7 @@ func (f *ConstraintFilter) Filter(config *dockerclient.ContainerConfig, nodes []
 			}
 		}
 		if len(candidates) == 0 {
-			return nil, fmt.Errorf("unable to find a node that satisfies %s = %s", k, v0)
+			return nil, fmt.Errorf("unable to find a node that satisfies %s=%s", k0, v0)
 		}
 		nodes = candidates
 	}

scheduler/filter/constraint_test.go

@@ -151,6 +151,44 @@ func TestConstraintNotExpr(t *testing.T) {
 	assert.Equal(t, result[0].Labels["region"], "eu")
 }
 
+func TestConstraintAlternativeNotExpr(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 does_not_exist. All should be found
+	result, err = f.Filter(&dockerclient.ContainerConfig{
+		Env: []string{"constraint:name!=does_not_exist"},
+	}, nodes)
+	assert.NoError(t, err)
+	assert.Len(t, result, 3)
+
+	// Check name must not start with n
+	result, err = f.Filter(&dockerclient.ContainerConfig{
+		Env: []string{"constraint:name!=n*"},
+	}, nodes)
+	assert.Error(t, err)
+	assert.Len(t, result, 0)
+
+	// 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")
+}
+
 func TestConstraintRegExp(t *testing.T) {
 	var (
 		f      = ConstraintFilter{}