argo-cd/controller/appcontroller.go

package controller

import (
	"context"
	"crypto/tls"
	"encoding/json"
	"fmt"
	"reflect"
	"runtime/debug"
	"strings"
	"sync"
	"time"

	"github.com/grpc-ecosystem/go-grpc-middleware"
	"github.com/grpc-ecosystem/go-grpc-middleware/logging/logrus"
	log "github.com/sirupsen/logrus"
	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/credentials"
	"google.golang.org/grpc/reflection"
	"google.golang.org/grpc/status"
	"k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/apimachinery/pkg/util/runtime"
	"k8s.io/apimachinery/pkg/util/wait"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/tools/cache"
	"k8s.io/client-go/util/workqueue"

	statecache "github.com/argoproj/argo-cd/controller/cache"
	"github.com/argoproj/argo-cd/controller/services"
	appv1 "github.com/argoproj/argo-cd/pkg/apis/application/v1alpha1"
	appclientset "github.com/argoproj/argo-cd/pkg/client/clientset/versioned"
	appinformers "github.com/argoproj/argo-cd/pkg/client/informers/externalversions"
	"github.com/argoproj/argo-cd/reposerver"
	"github.com/argoproj/argo-cd/util"
	"github.com/argoproj/argo-cd/util/argo"
	"github.com/argoproj/argo-cd/util/db"
	"github.com/argoproj/argo-cd/util/diff"
	grpc_util "github.com/argoproj/argo-cd/util/grpc"
	"github.com/argoproj/argo-cd/util/kube"
	settings_util "github.com/argoproj/argo-cd/util/settings"
	tlsutil "github.com/argoproj/argo-cd/util/tls"
)

const (
	updateOperationStateTimeout = 1 * time.Second
)

// ApplicationController is the controller for application resources.
type ApplicationController struct {
	namespace             string
	kubeClientset         kubernetes.Interface
	kubectl               kube.Kubectl
	applicationClientset  appclientset.Interface
	auditLogger           *argo.AuditLogger
	appRefreshQueue       workqueue.RateLimitingInterface
	appOperationQueue     workqueue.RateLimitingInterface
	appInformer           cache.SharedIndexInformer
	appStateManager       AppStateManager
	stateCache            statecache.LiveStateCache
	statusRefreshTimeout  time.Duration
	repoClientset         reposerver.Clientset
	db                    db.ArgoDB
	forceRefreshApps      map[string]bool
	forceRefreshAppsMutex *sync.Mutex
	managedResources      map[string][]managedResource
	managedResourcesMutex *sync.Mutex
}

type ApplicationControllerConfig struct {
	InstanceID string
	Namespace  string
}

// NewApplicationController creates new instance of ApplicationController.
func NewApplicationController(
	namespace string,
	kubeClientset kubernetes.Interface,
	applicationClientset appclientset.Interface,
	repoClientset reposerver.Clientset,
	appResyncPeriod time.Duration,
) *ApplicationController {
	settingsMgr := settings_util.NewSettingsManager(kubeClientset, namespace)
	db := db.NewDB(namespace, settingsMgr, kubeClientset)
	kubectlCmd := kube.KubectlCmd{}
	ctrl := ApplicationController{
		namespace:             namespace,
		kubeClientset:         kubeClientset,
		kubectl:               kubectlCmd,
		applicationClientset:  applicationClientset,
		repoClientset:         repoClientset,
		appRefreshQueue:       workqueue.NewRateLimitingQueue(workqueue.DefaultControllerRateLimiter()),
		appOperationQueue:     workqueue.NewRateLimitingQueue(workqueue.DefaultControllerRateLimiter()),
		db:                    db,
		statusRefreshTimeout:  appResyncPeriod,
		forceRefreshApps:      make(map[string]bool),
		forceRefreshAppsMutex: &sync.Mutex{},
		auditLogger:           argo.NewAuditLogger(namespace, kubeClientset, "application-controller"),
		managedResources:      make(map[string][]managedResource),
		managedResourcesMutex: &sync.Mutex{},
	}
	appInformer := ctrl.newApplicationInformer()
	stateCache := statecache.NewLiveStateCache(db, appInformer, kubectlCmd, func(appName string) {
		ctrl.forceAppRefresh(appName)
		ctrl.appRefreshQueue.Add(fmt.Sprintf("%s/%s", ctrl.namespace, appName))
	})
	appStateManager := NewAppStateManager(db, applicationClientset, repoClientset, namespace, kubectlCmd, stateCache)
	ctrl.appInformer = appInformer
	ctrl.appStateManager = appStateManager
	ctrl.stateCache = stateCache
	return &ctrl
}

func (ctrl *ApplicationController) getApp(name string) (*appv1.Application, error) {
	obj, exists, err := ctrl.appInformer.GetStore().GetByKey(fmt.Sprintf("%s/%s", ctrl.namespace, name))
	if err != nil {
		return nil, err
	}
	if !exists {
		return nil, status.Error(codes.NotFound, fmt.Sprintf("unable to find application with name %s", name))
	}
	a, ok := (obj).(*appv1.Application)
	if !ok {
		return nil, status.Errorf(codes.Internal, fmt.Sprintf("unexpected object type in app informer"))
	}
	return a, nil
}

func (ctrl *ApplicationController) setAppManagedResources(appName string, resources []managedResource) {
	ctrl.managedResourcesMutex.Lock()
	defer ctrl.managedResourcesMutex.Unlock()
	ctrl.managedResources[appName] = resources
}

func (ctrl *ApplicationController) getAppManagedResources(appName string) []managedResource {
	ctrl.managedResourcesMutex.Lock()
	defer ctrl.managedResourcesMutex.Unlock()
	return ctrl.managedResources[appName]
}

func (ctrl *ApplicationController) ResourceTree(ctx context.Context, q *services.ResourcesQuery) (*services.ResourceTreeResponse, error) {
	a, err := ctrl.getApp(q.ApplicationName)
	if err != nil {
		return nil, err
	}
	managedResources := ctrl.getAppManagedResources(q.ApplicationName)
	items := make([]*appv1.ResourceNode, 0)
	for i := range managedResources {
		managedResource := managedResources[i]
		node := appv1.ResourceNode{
			Name:      managedResource.Name,
			Version:   managedResource.Version,
			Kind:      managedResource.Kind,
			Group:     managedResource.Group,
			Namespace: managedResource.Namespace,
		}
		if managedResource.Live != nil {
			node.ResourceVersion = managedResource.Live.GetResourceVersion()
			children, err := ctrl.stateCache.GetChildren(a.Spec.Destination.Server, managedResource.Live)
			if err != nil {
				return nil, err
			}
			node.Children = children
		}
		items = append(items, &node)
	}
	return &services.ResourceTreeResponse{Items: items}, nil
}

func (ctrl *ApplicationController) ManagedResources(ctx context.Context, q *services.ResourcesQuery) (*services.ManagedResourcesResponse, error) {
	resources := ctrl.getAppManagedResources(q.ApplicationName)
	items := make([]*appv1.ResourceDiff, len(resources))
	for i := range resources {
		res := resources[i]
		item := appv1.ResourceDiff{
			Namespace: res.Namespace,
			Name:      res.Name,
			Group:     res.Group,
			Kind:      res.Kind,
		}
		live, data := hideSecretData(res.Live, nil)
		target, _ := hideSecretData(res.Target, data)

		if live != nil {
			data, err := json.Marshal(live)
			if err != nil {
				return nil, err
			}
			item.LiveState = string(data)
		} else {
			item.LiveState = "null"
		}

		if target != nil {
			data, err := json.Marshal(target)
			if err != nil {
				return nil, err
			}
			item.TargetState = string(data)
		} else {
			item.TargetState = "null"
		}
		jsonDiff, err := res.Diff.JSONFormat()
		if err != nil {
			return nil, err
		}
		item.Diff = jsonDiff

		items[i] = &item
	}
	return &services.ManagedResourcesResponse{Items: items}, nil
}

func toString(val interface{}) string {
	if val == nil {
		return ""
	}
	return fmt.Sprintf("%s", val)
}

// hideSecretData checks if given object kind is Secret, replaces data keys with stars and returns unchanged data map. The method additionally check if data key if different
// from corresponding key of optional parameter `otherData` and adds extra star to keep information about difference. So if secret data is out of sync user still can see which
// fields are different.
func hideSecretData(state *unstructured.Unstructured, otherData map[string]interface{}) (*unstructured.Unstructured, map[string]interface{}) {
	obj := state.DeepCopy()
	if obj != nil && obj.GroupVersionKind().Group == "" && obj.GetKind() == kube.SecretKind {
		if data, ok, err := unstructured.NestedMap(obj.Object, "data"); err == nil && ok {
			unchangedData := make(map[string]interface{})
			for k, v := range data {
				unchangedData[k] = v
			}
			for k := range data {
				replacement := "********"
				if otherData != nil {
					if val, ok := otherData[k]; ok && toString(val) != toString(data[k]) {
						replacement = replacement + "*"
					}
				}
				data[k] = replacement
			}
			_ = unstructured.SetNestedMap(obj.Object, data, "data")

			return obj, unchangedData
		}
	}
	return obj, nil
}

// Run starts the Application CRD controller.
func (ctrl *ApplicationController) Run(ctx context.Context, statusProcessors int, operationProcessors int) {
	defer runtime.HandleCrash()
	defer ctrl.appRefreshQueue.ShutDown()

	go ctrl.appInformer.Run(ctx.Done())

	if !cache.WaitForCacheSync(ctx.Done(), ctrl.appInformer.HasSynced) {
		log.Error("Timed out waiting for caches to sync")
		return
	}

	go ctrl.stateCache.Run(ctx)

	for i := 0; i < statusProcessors; i++ {
		go wait.Until(func() {
			for ctrl.processAppRefreshQueueItem() {
			}
		}, time.Second, ctx.Done())
	}

	for i := 0; i < operationProcessors; i++ {
		go wait.Until(func() {
			for ctrl.processAppOperationQueueItem() {
			}
		}, time.Second, ctx.Done())
	}

	<-ctx.Done()
}

func (ctrl *ApplicationController) CreateGRPC(tlsConfCustomizer tlsutil.ConfigCustomizer) (*grpc.Server, error) {
	// generate TLS cert
	hosts := []string{
		"localhost",
		"application-controller",
	}
	cert, err := tlsutil.GenerateX509KeyPair(tlsutil.CertOptions{
		Hosts:        hosts,
		Organization: "Argo CD",
		IsCA:         true,
	})

	if err != nil {
		return nil, err
	}

	tlsConfig := &tls.Config{Certificates: []tls.Certificate{*cert}}
	tlsConfCustomizer(tlsConfig)

	logEntry := log.NewEntry(log.New())
	server := grpc.NewServer(
		grpc.Creds(credentials.NewTLS(tlsConfig)),
		grpc.StreamInterceptor(grpc_middleware.ChainStreamServer(
			grpc_logrus.StreamServerInterceptor(logEntry),
			grpc_util.PanicLoggerStreamServerInterceptor(logEntry),
		)),
		grpc.UnaryInterceptor(grpc_middleware.ChainUnaryServer(
			grpc_logrus.UnaryServerInterceptor(logEntry),
			grpc_util.PanicLoggerUnaryServerInterceptor(logEntry),
		)),
	)
	services.RegisterApplicationServiceServer(server, ctrl)
	reflection.Register(server)
	return server, nil
}

func (ctrl *ApplicationController) forceAppRefresh(appName string) {
	ctrl.forceRefreshAppsMutex.Lock()
	defer ctrl.forceRefreshAppsMutex.Unlock()
	ctrl.forceRefreshApps[appName] = true
}

func (ctrl *ApplicationController) isRefreshForced(appName string) bool {
	ctrl.forceRefreshAppsMutex.Lock()
	defer ctrl.forceRefreshAppsMutex.Unlock()
	_, ok := ctrl.forceRefreshApps[appName]
	if ok {
		delete(ctrl.forceRefreshApps, appName)
	}
	return ok
}

func (ctrl *ApplicationController) processAppOperationQueueItem() (processNext bool) {
	appKey, shutdown := ctrl.appOperationQueue.Get()
	if shutdown {
		processNext = false
		return
	}
	processNext = true
	defer func() {
		if r := recover(); r != nil {
			log.Errorf("Recovered from panic: %+v\n%s", r, debug.Stack())
		}
		ctrl.appOperationQueue.Done(appKey)
	}()

	obj, exists, err := ctrl.appInformer.GetIndexer().GetByKey(appKey.(string))
	if err != nil {
		log.Errorf("Failed to get application '%s' from informer index: %+v", appKey, err)
		return
	}
	if !exists {
		// This happens after app was deleted, but the work queue still had an entry for it.
		return
	}
	app, ok := obj.(*appv1.Application)
	if !ok {
		log.Warnf("Key '%s' in index is not an application", appKey)
		return
	}
	if app.Operation != nil {
		ctrl.processRequestedAppOperation(app)
	} else if app.DeletionTimestamp != nil && app.CascadedDeletion() {
		err = ctrl.finalizeApplicationDeletion(app)
		if err != nil {
			ctrl.setAppCondition(app, appv1.ApplicationCondition{
				Type:    appv1.ApplicationConditionDeletionError,
				Message: err.Error(),
			})
			message := fmt.Sprintf("Unable to delete application resources: %v", err.Error())
			ctrl.auditLogger.LogAppEvent(app, argo.EventInfo{Reason: argo.EventReasonStatusRefreshed, Type: v1.EventTypeWarning}, message)
		}
	}
	return
}

func (ctrl *ApplicationController) finalizeApplicationDeletion(app *appv1.Application) error {
	logCtx := log.WithField("application", app.Name)
	logCtx.Infof("Deleting resources")
	// Get refreshed application info, since informer app copy might be stale
	app, err := ctrl.applicationClientset.ArgoprojV1alpha1().Applications(app.Namespace).Get(app.Name, metav1.GetOptions{})
	if err != nil {
		if !errors.IsNotFound(err) {
			logCtx.Errorf("Unable to get refreshed application info prior deleting resources: %v", err)
		}
		return nil
	}

	objsMap, err := ctrl.stateCache.GetManagedLiveObjs(app, []*unstructured.Unstructured{})
	if err != nil {
		return err
	}
	objs := make([]*unstructured.Unstructured, 0)
	for k := range objsMap {
		objs = append(objs, objsMap[k])
	}
	err = util.RunAllAsync(len(objs), func(i int) error {
		obj := objs[i]
		return ctrl.stateCache.Delete(app.Spec.Destination.Server, obj)
	})
	if err != nil {
		return err
	}

	objsMap, err = ctrl.stateCache.GetManagedLiveObjs(app, []*unstructured.Unstructured{})
	if err != nil {
		return err
	}
	if len(objsMap) > 0 {
		logCtx.Infof("%d objects remaining for deletion", len(objsMap))
		return nil
	}
	app.SetCascadedDeletion(false)
	var patch []byte
	patch, _ = json.Marshal(map[string]interface{}{
		"metadata": map[string]interface{}{
			"finalizers": app.Finalizers,
		},
	})
	_, err = ctrl.applicationClientset.ArgoprojV1alpha1().Applications(app.Namespace).Patch(app.Name, types.MergePatchType, patch)
	if err != nil {
		return err
	}

	logCtx.Info("Successfully deleted resources")
	return nil
}

func (ctrl *ApplicationController) setAppCondition(app *appv1.Application, condition appv1.ApplicationCondition) {
	index := -1
	for i, exiting := range app.Status.Conditions {
		if exiting.Type == condition.Type {
			index = i
			break
		}
	}
	if index > -1 {
		app.Status.Conditions[index] = condition
	} else {
		app.Status.Conditions = append(app.Status.Conditions, condition)
	}
	var patch []byte
	patch, err := json.Marshal(map[string]interface{}{
		"status": map[string]interface{}{
			"conditions": app.Status.Conditions,
		},
	})
	if err == nil {
		_, err = ctrl.applicationClientset.ArgoprojV1alpha1().Applications(app.Namespace).Patch(app.Name, types.MergePatchType, patch)
	}
	if err != nil {
		log.Errorf("Unable to set application condition: %v", err)
	}
}

func (ctrl *ApplicationController) processRequestedAppOperation(app *appv1.Application) {
	logCtx := log.WithField("application", app.Name)
	var state *appv1.OperationState
	// Recover from any unexpected panics and automatically set the status to be failed
	defer func() {
		if r := recover(); r != nil {
			logCtx.Errorf("Recovered from panic: %+v\n%s", r, debug.Stack())
			state.Phase = appv1.OperationError
			if rerr, ok := r.(error); ok {
				state.Message = rerr.Error()
			} else {
				state.Message = fmt.Sprintf("%v", r)
			}
			ctrl.setOperationState(app, state)
		}
	}()
	if isOperationInProgress(app) {
		// If we get here, we are about process an operation but we notice it is already in progress.
		// We need to detect if the app object we pulled off the informer is stale and doesn't
		// reflect the fact that the operation is completed. We don't want to perform the operation
		// again. To detect this, always retrieve the latest version to ensure it is not stale.
		freshApp, err := ctrl.applicationClientset.ArgoprojV1alpha1().Applications(ctrl.namespace).Get(app.ObjectMeta.Name, metav1.GetOptions{})
		if err != nil {
			logCtx.Errorf("Failed to retrieve latest application state: %v", err)
			return
		}
		if !isOperationInProgress(freshApp) {
			logCtx.Infof("Skipping operation on stale application state")
			return
		}
		app = freshApp
		state = app.Status.OperationState.DeepCopy()
		logCtx.Infof("Resuming in-progress operation. phase: %s, message: %s", state.Phase, state.Message)
	} else {
		state = &appv1.OperationState{Phase: appv1.OperationRunning, Operation: *app.Operation, StartedAt: metav1.Now()}
		ctrl.setOperationState(app, state)
		logCtx.Infof("Initialized new operation: %v", *app.Operation)
	}
	ctrl.appStateManager.SyncAppState(app, state)

	if state.Phase == appv1.OperationRunning {
		// It's possible for an app to be terminated while we were operating on it. We do not want
		// to clobber the Terminated state with Running. Get the latest app state to check for this.
		freshApp, err := ctrl.applicationClientset.ArgoprojV1alpha1().Applications(ctrl.namespace).Get(app.ObjectMeta.Name, metav1.GetOptions{})
		if err == nil {
			if freshApp.Status.OperationState != nil && freshApp.Status.OperationState.Phase == appv1.OperationTerminating {
				state.Phase = appv1.OperationTerminating
				state.Message = "operation is terminating"
				// after this, we will get requeued to the workqueue, but next time the
				// SyncAppState will operate in a Terminating phase, allowing the worker to perform
				// cleanup (e.g. delete jobs, workflows, etc...)
			}
		}
	}

	ctrl.setOperationState(app, state)
	if state.Phase.Completed() {
		// if we just completed an operation, force a refresh so that UI will report up-to-date
		// sync/health information
		ctrl.forceAppRefresh(app.ObjectMeta.Name)
	}
}

func (ctrl *ApplicationController) setOperationState(app *appv1.Application, state *appv1.OperationState) {
	util.RetryUntilSucceed(func() error {
		if state.Phase == "" {
			// expose any bugs where we neglect to set phase
			panic("no phase was set")
		}
		if state.Phase.Completed() {
			now := metav1.Now()
			state.FinishedAt = &now
		}
		patch := map[string]interface{}{
			"status": map[string]interface{}{
				"operationState": state,
			},
		}
		if state.Phase.Completed() {
			// If operation is completed, clear the operation field to indicate no operation is
			// in progress.
			patch["operation"] = nil
		}
		if reflect.DeepEqual(app.Status.OperationState, state) {
			log.Infof("No operation updates necessary to '%s'. Skipping patch", app.Name)
			return nil
		}
		patchJSON, err := json.Marshal(patch)
		if err != nil {
			return err
		}
		appClient := ctrl.applicationClientset.ArgoprojV1alpha1().Applications(ctrl.namespace)
		_, err = appClient.Patch(app.Name, types.MergePatchType, patchJSON)
		if err != nil {
			return err
		}
		log.Infof("updated '%s' operation (phase: %s)", app.Name, state.Phase)
		if state.Phase.Completed() {
			eventInfo := argo.EventInfo{Reason: argo.EventReasonOperationCompleted}
			var messages []string
			if state.Operation.Sync != nil && len(state.Operation.Sync.Resources) > 0 {
				messages = []string{"Partial sync operation"}
			} else {
				messages = []string{"Sync operation"}
			}
			if state.SyncResult != nil {
				messages = append(messages, "to", state.SyncResult.Revision)
			}
			if state.Phase.Successful() {
				eventInfo.Type = v1.EventTypeNormal
				messages = append(messages, "succeeded")
			} else {
				eventInfo.Type = v1.EventTypeWarning
				messages = append(messages, "failed:", state.Message)
			}
			ctrl.auditLogger.LogAppEvent(app, eventInfo, strings.Join(messages, " "))
		}
		return nil
	}, "Update application operation state", context.Background(), updateOperationStateTimeout)
}

func (ctrl *ApplicationController) processAppRefreshQueueItem() (processNext bool) {
	appKey, shutdown := ctrl.appRefreshQueue.Get()
	if shutdown {
		processNext = false
		return
	}
	processNext = true
	defer func() {
		if r := recover(); r != nil {
			log.Errorf("Recovered from panic: %+v\n%s", r, debug.Stack())
		}
		ctrl.appRefreshQueue.Done(appKey)
	}()

	obj, exists, err := ctrl.appInformer.GetIndexer().GetByKey(appKey.(string))
	if err != nil {
		log.Errorf("Failed to get application '%s' from informer index: %+v", appKey, err)
		return
	}
	if !exists {
		// This happens after app was deleted, but the work queue still had an entry for it.
		return
	}
	origApp, ok := obj.(*appv1.Application)
	if !ok {
		log.Warnf("Key '%s' in index is not an application", appKey)
		return
	}
	if !ctrl.needRefreshAppStatus(origApp, ctrl.statusRefreshTimeout) {
		return
	}
	// NOTE: normalization returns a copy
	app := ctrl.normalizeApplication(origApp)

	conditions, hasErrors := ctrl.refreshAppConditions(app)
	if hasErrors {
		app.Status.Sync.Status = appv1.SyncStatusCodeUnknown
		app.Status.Health.Status = appv1.HealthStatusUnknown
		app.Status.Conditions = conditions
		ctrl.persistAppStatus(origApp, &app.Status)
		return
	}

	compareResult, err := ctrl.appStateManager.CompareAppState(app, "", nil)
	if err != nil {
		conditions = append(conditions, appv1.ApplicationCondition{Type: appv1.ApplicationConditionComparisonError, Message: err.Error()})
	} else {
		conditions = append(conditions, compareResult.conditions...)
	}
	ctrl.setAppManagedResources(app.Name, compareResult.managedResources)

	syncErrCond := ctrl.autoSync(app, compareResult.syncStatus)
	if syncErrCond != nil {
		conditions = append(conditions, *syncErrCond)
	}

	app.Status.ObservedAt = compareResult.observedAt
	app.Status.Sync = *compareResult.syncStatus
	app.Status.Health = *compareResult.healthStatus
	app.Status.Resources = compareResult.resources
	app.Status.Conditions = conditions
	ctrl.persistAppStatus(origApp, &app.Status)
	return
}

// needRefreshAppStatus answers if application status needs to be refreshed.
// Returns true if application never been compared, has changed or comparison result has expired.
func (ctrl *ApplicationController) needRefreshAppStatus(app *appv1.Application, statusRefreshTimeout time.Duration) bool {
	logCtx := log.WithFields(log.Fields{"application": app.Name})
	var reason string
	expired := app.Status.ObservedAt.Add(statusRefreshTimeout).Before(time.Now().UTC())
	if ctrl.isRefreshForced(app.Name) {
		reason = "force refresh"
	} else if app.Status.Sync.Status == appv1.SyncStatusCodeUnknown && expired {
		reason = "comparison status unknown"
	} else if !app.Spec.Source.Equals(app.Status.Sync.ComparedTo) {
		reason = "spec.source differs"
	} else if expired {
		reason = fmt.Sprintf("comparison expired. observedAt: %v, expiry: %v", app.Status.ObservedAt, statusRefreshTimeout)
	}
	if reason != "" {
		logCtx.Infof("Refreshing app status (%s)", reason)
		return true
	}
	return false
}

func (ctrl *ApplicationController) refreshAppConditions(app *appv1.Application) ([]appv1.ApplicationCondition, bool) {
	conditions := make([]appv1.ApplicationCondition, 0)
	proj, err := argo.GetAppProject(&app.Spec, ctrl.applicationClientset, ctrl.namespace)
	if err != nil {
		if errors.IsNotFound(err) {
			conditions = append(conditions, appv1.ApplicationCondition{
				Type:    appv1.ApplicationConditionInvalidSpecError,
				Message: fmt.Sprintf("Application referencing project %s which does not exist", app.Spec.Project),
			})
		} else {
			conditions = append(conditions, appv1.ApplicationCondition{
				Type:    appv1.ApplicationConditionUnknownError,
				Message: err.Error(),
			})
		}
	} else {
		specConditions, err := argo.GetSpecErrors(context.Background(), &app.Spec, proj, ctrl.repoClientset, ctrl.db)
		if err != nil {
			conditions = append(conditions, appv1.ApplicationCondition{
				Type:    appv1.ApplicationConditionUnknownError,
				Message: err.Error(),
			})
		} else {
			conditions = append(conditions, specConditions...)
		}
	}

	// List of condition types which have to be reevaluated by controller; all remaining conditions should stay as is.
	reevaluateTypes := map[appv1.ApplicationConditionType]bool{
		appv1.ApplicationConditionInvalidSpecError:      true,
		appv1.ApplicationConditionUnknownError:          true,
		appv1.ApplicationConditionComparisonError:       true,
		appv1.ApplicationConditionSharedResourceWarning: true,
		appv1.ApplicationConditionSyncError:             true,
	}
	appConditions := make([]appv1.ApplicationCondition, 0)
	for i := 0; i < len(app.Status.Conditions); i++ {
		condition := app.Status.Conditions[i]
		if _, ok := reevaluateTypes[condition.Type]; !ok {
			appConditions = append(appConditions, condition)
		}
	}
	hasErrors := false
	for i := range conditions {
		condition := conditions[i]
		appConditions = append(appConditions, condition)
		if condition.IsError() {
			hasErrors = true
		}

	}
	return appConditions, hasErrors
}

// normalizeApplication normalizes an application.spec and additionally persists updates if it changed
// Always returns a copy of the application
func (ctrl *ApplicationController) normalizeApplication(app *appv1.Application) *appv1.Application {
	logCtx := log.WithFields(log.Fields{"application": app.Name})
	appClient := ctrl.applicationClientset.ArgoprojV1alpha1().Applications(app.Namespace)
	modifiedApp := app.DeepCopy()
	modifiedApp.Spec = *argo.NormalizeApplicationSpec(&app.Spec)
	patch, modified, err := diff.CreateTwoWayMergePatch(app, modifiedApp, appv1.Application{})
	if err != nil {
		logCtx.Errorf("error constructing app spec patch: %v", err)
		return modifiedApp
	} else if modified {
		_, err = appClient.Patch(app.Name, types.MergePatchType, patch)
		if err != nil {
			logCtx.Errorf("Error persisting normalized application spec: %v", err)
		} else {
			logCtx.Infof("Normalized app spec: %s", string(patch))
		}
	}
	return modifiedApp
}

// persistAppStatus persists updates to application status. If no changes were made, it is a no-op
func (ctrl *ApplicationController) persistAppStatus(orig *appv1.Application, newStatus *appv1.ApplicationStatus) {
	logCtx := log.WithFields(log.Fields{"application": orig.Name})
	if orig.Status.Sync.Status != newStatus.Sync.Status {
		message := fmt.Sprintf("Updated sync status: %s -> %s", orig.Status.Sync.Status, newStatus.Sync.Status)
		ctrl.auditLogger.LogAppEvent(orig, argo.EventInfo{Reason: argo.EventReasonResourceUpdated, Type: v1.EventTypeNormal}, message)
	}
	if orig.Status.Health.Status != newStatus.Health.Status {
		message := fmt.Sprintf("Updated health status: %s -> %s", orig.Status.Health.Status, newStatus.Health.Status)
		ctrl.auditLogger.LogAppEvent(orig, argo.EventInfo{Reason: argo.EventReasonResourceUpdated, Type: v1.EventTypeNormal}, message)
	}
	patch, modified, err := diff.CreateTwoWayMergePatch(&appv1.Application{Status: orig.Status}, &appv1.Application{Status: *newStatus}, appv1.Application{})
	if err != nil {
		logCtx.Errorf("Error constructing app status patch: %v", err)
		return
	}
	if !modified {
		logCtx.Infof("No status changes. Skipping patch")
		return
	}
	appClient := ctrl.applicationClientset.ArgoprojV1alpha1().Applications(orig.Namespace)
	_, err = appClient.Patch(orig.Name, types.MergePatchType, patch)
	if err != nil {
		logCtx.Warnf("Error updating application: %v", err)
	} else {
		logCtx.Infof("Update successful")
	}
}

// autoSync will initiate a sync operation for an application configured with automated sync
func (ctrl *ApplicationController) autoSync(app *appv1.Application, syncStatus *appv1.SyncStatus) *appv1.ApplicationCondition {
	if app.Spec.SyncPolicy == nil || app.Spec.SyncPolicy.Automated == nil {
		return nil
	}
	logCtx := log.WithFields(log.Fields{"application": app.Name})
	if app.Operation != nil {
		logCtx.Infof("Skipping auto-sync: another operation is in progress")
		return nil
	}
	// Only perform auto-sync if we detect OutOfSync status. This is to prevent us from attempting
	// a sync when application is already in a Synced or Unknown state
	if syncStatus.Status != appv1.SyncStatusCodeOutOfSync {
		logCtx.Infof("Skipping auto-sync: application status is %s", syncStatus.Status)
		return nil
	}
	desiredCommitSHA := syncStatus.Revision

	// It is possible for manifests to remain OutOfSync even after a sync/kubectl apply (e.g.
	// auto-sync with pruning disabled). We need to ensure that we do not keep Syncing an
	// application in an infinite loop. To detect this, we only attempt the Sync if the revision
	// and parameter overrides are different from our most recent sync operation.
	if alreadyAttemptedSync(app, desiredCommitSHA) {
		if app.Status.OperationState.Phase != appv1.OperationSucceeded {
			logCtx.Warnf("Skipping auto-sync: failed previous sync attempt to %s", desiredCommitSHA)
			message := fmt.Sprintf("Failed sync attempt to %s: %s", desiredCommitSHA, app.Status.OperationState.Message)
			return &appv1.ApplicationCondition{Type: appv1.ApplicationConditionSyncError, Message: message}
		}
		logCtx.Infof("Skipping auto-sync: most recent sync already to %s", desiredCommitSHA)
		return nil
	}

	op := appv1.Operation{
		Sync: &appv1.SyncOperation{
			Revision:           desiredCommitSHA,
			Prune:              app.Spec.SyncPolicy.Automated.Prune,
			ParameterOverrides: app.Spec.Source.ComponentParameterOverrides,
		},
	}
	appIf := ctrl.applicationClientset.ArgoprojV1alpha1().Applications(app.Namespace)
	_, err := argo.SetAppOperation(appIf, app.Name, &op)
	if err != nil {
		logCtx.Errorf("Failed to initiate auto-sync to %s: %v", desiredCommitSHA, err)
		return &appv1.ApplicationCondition{Type: appv1.ApplicationConditionSyncError, Message: err.Error()}
	}
	message := fmt.Sprintf("Initiated automated sync to '%s'", desiredCommitSHA)
	ctrl.auditLogger.LogAppEvent(app, argo.EventInfo{Reason: argo.EventReasonOperationStarted, Type: v1.EventTypeNormal}, message)
	logCtx.Info(message)
	return nil
}

// alreadyAttemptedSync returns whether or not the most recent sync was performed against the
// commitSHA and with the same parameter overrides which are currently set in the app
func alreadyAttemptedSync(app *appv1.Application, commitSHA string) bool {
	if app.Status.OperationState == nil || app.Status.OperationState.Operation.Sync == nil || app.Status.OperationState.SyncResult == nil {
		return false
	}
	if app.Status.OperationState.SyncResult.Revision != commitSHA {
		return false
	}
	if !reflect.DeepEqual(appv1.ParameterOverrides(app.Spec.Source.ComponentParameterOverrides), app.Status.OperationState.Operation.Sync.ParameterOverrides) {
		return false
	}
	return true
}

func (ctrl *ApplicationController) newApplicationInformer() cache.SharedIndexInformer {
	appInformerFactory := appinformers.NewFilteredSharedInformerFactory(
		ctrl.applicationClientset,
		ctrl.statusRefreshTimeout,
		ctrl.namespace,
		func(options *metav1.ListOptions) {},
	)
	informer := appInformerFactory.Argoproj().V1alpha1().Applications().Informer()
	informer.AddEventHandler(
		cache.ResourceEventHandlerFuncs{
			AddFunc: func(obj interface{}) {
				key, err := cache.MetaNamespaceKeyFunc(obj)
				if err == nil {
					ctrl.appRefreshQueue.Add(key)
					ctrl.appOperationQueue.Add(key)
				}
			},
			UpdateFunc: func(old, new interface{}) {
				key, err := cache.MetaNamespaceKeyFunc(new)
				if err != nil {
					return
				}
				oldApp, oldOK := old.(*appv1.Application)
				newApp, newOK := new.(*appv1.Application)
				if oldOK && newOK {
					if toggledAutomatedSync(oldApp, newApp) {
						log.WithField("application", newApp.Name).Info("Enabled automated sync")
						ctrl.forceAppRefresh(newApp.Name)
					}
				}
				ctrl.appRefreshQueue.Add(key)
				ctrl.appOperationQueue.Add(key)
			},
			DeleteFunc: func(obj interface{}) {
				// IndexerInformer uses a delta queue, therefore for deletes we have to use this
				// key function.
				key, err := cache.DeletionHandlingMetaNamespaceKeyFunc(obj)
				if err == nil {
					ctrl.appRefreshQueue.Add(key)
				}
			},
		},
	)
	return informer
}

func isOperationInProgress(app *appv1.Application) bool {
	return app.Status.OperationState != nil && !app.Status.OperationState.Phase.Completed()
}

// toggledAutomatedSync tests if an app went from auto-sync disabled to enabled.
// if it was toggled to be enabled, the informer handler will force a refresh
func toggledAutomatedSync(old *appv1.Application, new *appv1.Application) bool {
	if new.Spec.SyncPolicy == nil || new.Spec.SyncPolicy.Automated == nil {
		return false
	}
	// auto-sync is enabled. check if it was previously disabled
	if old.Spec.SyncPolicy == nil || old.Spec.SyncPolicy.Automated == nil {
		return true
	}
	// nothing changed
	return false
}