Support Build Expressions with fail format

pkg/platform/runtime/buildexpression/buildexpression.go

@@ -84,6 +84,10 @@ type In struct {
 	Name     *string
 }
 
+type Fail struct {
+	Message string
+}
+
 // New creates a BuildExpression from a JSON byte array.
 // The JSON must be a valid BuildExpression in the following format:
 //
@@ -143,6 +147,12 @@ func New(data []byte) (*BuildExpression, error) {
 				}
 
 				expr.Let = let
+			} else if key == "fail" {
+				fail, err := newFail(path, v)
+				if err != nil {
+					return nil, errs.Wrap(err, "Could not parse 'fail' key")
+				}
+				return nil, locale.NewError("err_build_expression_fail", "", fail.Message)
 			} else if isAp(path, v) {
 				ap, err := newAp(path, v)
 				if err != nil {
@@ -453,6 +463,28 @@ func newIn(path []string, inValue interface{}) (*In, error) {
 	return in, nil
 }
 
+func newFail(path []string, m map[string]interface{}) (*Fail, error) {
+	path = append(path, "fail")
+	defer func() {
+		_, _, err := sliceutils.Pop(path)
+		if err != nil {
+			multilog.Error("Could not pop context: %v", err)
+		}
+	}()
+
+	message, ok := m["message"]
+	if !ok {
+		return nil, errs.New("Build expression's 'fail' object has no 'message' key")
+	}
+
+	messageStr, ok := message.(string)
+	if !ok {
+		return nil, errs.New("'message' key's value is not a string")
+	}
+
+	return &Fail{Message: messageStr}, nil
+}
+
 // validateRequirements ensures that the requirements in the BuildExpression contain
 // both the name and namespace fields. These fileds are used for requirement operations.
 func (e *BuildExpression) validateRequirements() error {

pkg/platform/runtime/buildexpression/buildexpression_test.go

@@ -70,6 +70,13 @@ func TestNew(t *testing.T) {
 			},
 			wantErr: false,
 		},
+		{
+			name: "fail",
+			args: args{
+				filename: "buildexpression-fail.json",
+			},
+			wantErr: true,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {

pkg/platform/runtime/buildexpression/testdata/buildexpression-fail.json

@@ -0,0 +1,5 @@
+{
+    "fail": {
+        "message": "invalid order"
+    }
+}