WIP Improve new-build output cycle detection

pkg/generate/app/cmd/newapp.go

@@ -717,6 +717,20 @@ func (c *AppConfig) checkCircularReferences(objects app.Objects) error {
 	return nil
 }
 
+// checkCircularReference returns an error if the output of the BuildConfig bc
+// matches the build input and would automatically trigger build after build in
+// a loop through an ImageChange trigger.
+func checkCircularReference(bc *buildapi.BuildConfig) error {
+	if bc == nil {
+		return nil
+	}
+	input := buildutil.GetInputReference(bc.Spec.Strategy)
+	if bc.Spec.Output.To != nil && input != nil && reflect.DeepEqual(input, bc.Spec.Output.To) {
+		return app.CircularOutputReferenceError{Reference: fmt.Sprintf("%s", input.Name)}
+	}
+	return nil
+}
+
 func (c *AppConfig) Querying() bool {
 	return c.AsList || c.AsSearch
 }

pkg/generate/app/cmd/newapp_test.go

@@ -15,6 +15,7 @@ import (
 	"k8s.io/kubernetes/pkg/runtime"
 	"k8s.io/kubernetes/pkg/util/sets"
 
+	buildapi "github.com/openshift/origin/pkg/build/api"
 	client "github.com/openshift/origin/pkg/client/testclient"
 	"github.com/openshift/origin/pkg/generate/app"
 	templateapi "github.com/openshift/origin/pkg/template/api"
@@ -400,3 +401,64 @@ func TestBuildPipelinesWithUnresolvedImage(t *testing.T) {
 		t.Errorf("Expected ports=%v, got %v", e, a)
 	}
 }
+
+func TestCheckCircularReference(t *testing.T) {
+	tests := []struct {
+		name string
+		bc   *buildapi.BuildConfig
+		err  error
+	}{
+		{
+			name: "no nil pointer dereference",
+			bc:   nil,
+			err:  nil,
+		},
+		{
+			name: "no output == no circular reference",
+			bc:   &buildapi.BuildConfig{},
+			err:  nil,
+		},
+		{
+			name: "no triggers == no build loop",
+			bc: &buildapi.BuildConfig{
+				Spec: buildapi.BuildConfigSpec{
+					Triggers:  []buildapi.BuildTriggerPolicy{},
+					BuildSpec: buildapi.BuildSpec{},
+				},
+			},
+			err: nil,
+		},
+		{
+			name: "ImageChange trigger + (input == output) == error",
+			bc: &buildapi.BuildConfig{
+				Spec: buildapi.BuildConfigSpec{
+					Triggers: []buildapi.BuildTriggerPolicy{
+						{Type: buildapi.ImageChangeBuildTriggerType},
+					},
+					BuildSpec: buildapi.BuildSpec{
+						Strategy: buildapi.BuildStrategy{
+							SourceStrategy: &buildapi.SourceBuildStrategy{
+								From: kapi.ObjectReference{
+									Kind: "ImageStreamTag",
+									Name: "centos:latest",
+								},
+							},
+						},
+						Output: buildapi.BuildOutput{
+							To: &kapi.ObjectReference{
+								Kind: "ImageStreamTag",
+								Name: "centos:latest",
+							},
+						},
+					},
+				},
+			},
+			err: app.CircularOutputReferenceError{Reference: "centos:latest"},
+		},
+	}
+	for _, tt := range tests {
+		if got := checkCircularReference(tt.bc); got != tt.err {
+			t.Errorf("test: %s\ncheckCircularReference(bc) = %v, want %v", tt.name, got, tt.err)
+		}
+	}
+}