Add simple application pattern package

pkg/patterns/application/application.go

@@ -0,0 +1,178 @@
+/*
+Copyright 2018 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package application
+
+import (
+	"fmt"
+	"strings"
+
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/client-go/rest"
+	"sigs.k8s.io/controller-runtime/pkg/client/apiutil"
+	"sigs.k8s.io/controller-runtime/pkg/client/config"
+	"sigs.k8s.io/controller-runtime/pkg/controller"
+	"sigs.k8s.io/controller-runtime/pkg/handler"
+	"sigs.k8s.io/controller-runtime/pkg/manager"
+	"sigs.k8s.io/controller-runtime/pkg/predicate"
+	"sigs.k8s.io/controller-runtime/pkg/reconcile"
+	"sigs.k8s.io/controller-runtime/pkg/source"
+)
+
+// application is a simple Controller for a single API type.  It will create a Manager for itself
+// if one is not provided.
+type application struct {
+	mgr  manager.Manager
+	ctrl controller.Controller
+}
+
+// Supporting mocking out functions for testing
+var getConfig = config.GetConfig
+var newController = controller.New
+var newManager = manager.New
+var getGvk = apiutil.GVKForObject
+
+// Builder builds an Application Controller (e.g. Operator) and returns a manager.Manager to start it.
+type Builder struct {
+	apiType        runtime.Object
+	mgr            manager.Manager
+	predicates     []predicate.Predicate
+	managedObjects []runtime.Object
+	config         *rest.Config
+	reconcile      reconcile.Reconciler
+	ctrl           controller.Controller
+}
+
+// BuilderFor returns a new Builder for and BuilderFor
+func BuilderFor(apiType runtime.Object) *Builder {
+	return &Builder{apiType: apiType}
+}
+
+// Owns configures the Application Controller to respond to create / delete / update events for objects it managedObjects
+// - e.g. creates.  apiType is an empty instance of an object matching the managed object type.
+func (b *Builder) Owns(apiType runtime.Object) *Builder {
+	b.managedObjects = append(b.managedObjects, apiType)
+	return b
+}
+
+// WithConfig sets the Config to use for configuring clients.  Defaults to the in-cluster config or to ~/.kube/config.
+func (b *Builder) WithConfig(config *rest.Config) *Builder {
+	b.config = config
+	return b
+}
+
+// WithManager sets the Manager to use for registering the Controller.  Defaults to a new manager.Manager.
+func (b *Builder) WithManager(m manager.Manager) *Builder {
+	b.mgr = m
+	return b
+}
+
+// WithEventFilter sets the event filters, to filter which create/update/delete/generic events eventually
+// trigger reconciliations.  For example, filtering on whether the resource version has changed.
+// Defaults to the empty list.
+func (b *Builder) WithEventFilter(p predicate.Predicate) *Builder {
+	b.predicates = append(b.predicates, p)
+	return b
+}
+
+// WithReconciler sets the Reconcile called in response to create / update / delete events for the
+// BuilderFor type or Created object types.
+func (b *Builder) WithReconciler(r reconcile.Reconciler) *Builder {
+	b.reconcile = r
+	return b
+}
+
+// Build builds the Application Controller and returns the Manager used to start it.
+func (b *Builder) Build() (manager.Manager, error) {
+	if b.reconcile == nil {
+		return nil, fmt.Errorf("must call WithReconciler to set Reconciler")
+	}
+
+	// Set the Config
+	if err := b.doConfig(); err != nil {
+		return nil, err
+	}
+
+	// Set the Manager
+	if err := b.doManager(); err != nil {
+		return nil, err
+	}
+
+	// Set the Controller
+	if err := b.doController(); err != nil {
+		return nil, err
+	}
+
+	a := &application{mgr: b.mgr, ctrl: b.ctrl}
+
+	// Reconcile type
+	s := &source.Kind{Type: b.apiType}
+	h := &handler.EnqueueRequestForObject{}
+	err := a.ctrl.Watch(s, h, b.predicates...)
+	if err != nil {
+		return nil, err
+	}
+
+	// Watch the managed types
+	for _, t := range b.managedObjects {
+		s := &source.Kind{Type: t}
+		h := &handler.EnqueueRequestForOwner{
+			OwnerType:    b.apiType,
+			IsController: true,
+		}
+		if err := a.ctrl.Watch(s, h, b.predicates...); err != nil {
+			return nil, err
+		}
+	}
+
+	return a.mgr, nil
+}
+
+func (b *Builder) doConfig() error {
+	if b.config != nil {
+		return nil
+	}
+	var err error
+	b.config, err = getConfig()
+	return err
+}
+
+func (b *Builder) doManager() error {
+	if b.mgr != nil {
+		return nil
+	}
+	var err error
+	b.mgr, err = newManager(b.config, manager.Options{})
+	return err
+}
+
+func (b *Builder) getControllerName() (string, error) {
+	gvk, err := getGvk(b.apiType, b.mgr.GetScheme())
+	if err != nil {
+		return "", err
+	}
+	name := fmt.Sprintf("%s-application", strings.ToLower(gvk.Kind))
+	return name, nil
+}
+
+func (b *Builder) doController() error {
+	name, err := b.getControllerName()
+	if err != nil {
+		return err
+	}
+	b.ctrl, err = newController(name, b.mgr, controller.Options{Reconciler: b.reconcile})
+	return err
+}

pkg/patterns/application/application_suite_test.go

@@ -0,0 +1,35 @@
+package application
+
+import (
+	"testing"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+	"k8s.io/client-go/rest"
+	"sigs.k8s.io/controller-runtime/pkg/envtest"
+	logf "sigs.k8s.io/controller-runtime/pkg/runtime/log"
+)
+
+func TestSource(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecsWithDefaultAndCustomReporters(t, "application Suite", []Reporter{envtest.NewlineReporter{}})
+}
+
+var testenv *envtest.Environment
+var cfg *rest.Config
+
+var _ = BeforeSuite(func(done Done) {
+	logf.SetLogger(logf.ZapLogger(false))
+
+	testenv = &envtest.Environment{}
+
+	var err error
+	cfg, err = testenv.Start()
+	Expect(err).NotTo(HaveOccurred())
+
+	close(done)
+}, 60)
+
+var _ = AfterSuite(func() {
+	testenv.Stop()
+})