feat: support multiple InitTargets for the same WorkspaceType (#20)

Previously, init-agent documentation stated that only a single InitTarget
per WorkspaceType was supported — a second InitTarget referencing the
same WorkspaceType would race the first and one set of templates could
be silently skipped.

This change makes multiple InitTargets per WorkspaceType a first-class
feature. The targetcontroller now keys controllers by WorkspaceType
reference (path:name) instead of InitTarget UID. Sources from all
matching InitTargets are aggregated into a single initialization pass,
and the initializer is only removed after every source from every
target is applied.

- internal/controller/targetcontroller: key by WSType ref, track
  InitTarget names per key, aggregate provider returns all matching
  targets, cancel manager only when the last target is deleted.
- internal/controller/initcontroller: InitTargetsProvider returns
  []*InitTarget; reconcile iterates sources from all of them.
- Rename InitTargetProvider -> InitTargetsProvider (plural) per
  review feedback from @xrstf.

Fixes #17

Signed-off-by: Igor Fominykh <ifdotpy@gmail.com>

Author: ifdotpy

cmd/init-agent/main.go

@@ -119,7 +119,7 @@ func run(ctx context.Context, log *zap.SugaredLogger, opts *Options) error {
 
 	// wrap this controller creation in a closure to prevent giving all the initcontroller
 	// dependencies to the targetcontroller
-	newInitController := func(remoteManager mcmanager.Manager, targetProvider initcontroller.InitTargetProvider, initializer kcpcorev1alpha1.LogicalClusterInitializer) error {
+	newInitController := func(remoteManager mcmanager.Manager, targetProvider initcontroller.InitTargetsProvider, initializer kcpcorev1alpha1.LogicalClusterInitializer) error {
 		return initcontroller.Create(remoteManager, targetProvider, sourceFactory, manifestApplier, initializer, log, numInitWorkers)
 	}
 

docs/content/setup/development.md

@@ -21,8 +21,11 @@ that backs a workspace. Initializers are the cluster name + name of the `Workspa
     removed once from a `LogicalCluster`, it's critical that you use dedicated workspace types for
     every bootstrapping purpose.
 
-    This means there can only be exactly one `InitTarget` in the entire kcp installation that refers
-    to a `WorkspaceType`. And only a single init-agent may process each `InitTarget`.
+    Multiple `InitTarget` resources may refer to the same `WorkspaceType`. The init-agent aggregates
+    the sources from all of them into a single initialization pass and only removes the initializer
+    after every source from every target has been applied. This lets you compose bootstrapping
+    behavior from independently authored `InitTargets` (e.g. RBAC, quotas, networking) without
+    racing on the initializer. Only a single init-agent may process a given `WorkspaceType`.
 
     **Do not** use the init-agent with kcp's own `WorkspaceTypes`, as this could interfere with
     kcp's core functionality.

internal/controller/initcontroller/controller.go

@@ -38,11 +38,11 @@ const (
 	ControllerName = "initagent-init"
 )
 
-type InitTargetProvider func(ctx context.Context) (*initializationv1alpha1.InitTarget, error)
+type InitTargetsProvider func(ctx context.Context) ([]*initializationv1alpha1.InitTarget, error)
 
 type Reconciler struct {
 	remoteManager   mcmanager.Manager
-	targetProvider  InitTargetProvider
+	targetProvider  InitTargetsProvider
 	log             *zap.SugaredLogger
 	sourceFactory   *source.Factory
 	manifestApplier manifest.Applier
@@ -53,7 +53,7 @@ type Reconciler struct {
 // as this controller is started/stopped by the syncmanager controller instead.
 func Create(
 	remoteManager mcmanager.Manager,
-	targetProvider InitTargetProvider,
+	targetProvider InitTargetsProvider,
 	sourceFactory *source.Factory,
 	manifestApplier manifest.Applier,
 	initializer kcpcorev1alpha1.LogicalClusterInitializer,

internal/controller/initcontroller/reconciler.go

@@ -89,38 +89,40 @@ func (r *Reconciler) Reconcile(ctx context.Context, request mcreconcile.Request)
 }
 
 func (r *Reconciler) reconcile(ctx context.Context, logger *zap.SugaredLogger, client ctrlruntimeclient.Client, lc *kcpcorev1alpha1.LogicalCluster) (requeue bool, err error) {
-	// Dynamically fetch the latest InitTarget, so that we do not have to restart
-	// (and re-cache) this controller everytime an InitTarget changes.
-	target, err := r.targetProvider(ctx)
+	// Dynamically fetch all InitTargets for this WorkspaceType, so that we do not
+	// have to restart (and re-cache) this controller everytime an InitTarget changes.
+	targets, err := r.targetProvider(ctx)
 	if err != nil {
-		return requeue, fmt.Errorf("failed to get InitTarget: %w", err)
+		return requeue, fmt.Errorf("failed to get InitTargets: %w", err)
 	}
 
-	for idx, ref := range target.Spec.Sources {
-		sourceLog := logger.With("init-target", target.Name, "source-idx", idx)
-		sourceCtx := log.WithLog(ctx, sourceLog)
-
-		src, err := r.sourceFactory.NewForInitSource(sourceCtx, kcp.ClusterNameFromObject(target), ref)
-		if err != nil {
-			return requeue, fmt.Errorf("failed to initialize source #%d: %w", idx, err)
-		}
-
-		objects, err := src.Manifests(lc)
-		if err != nil {
-			return requeue, fmt.Errorf("failed to render source #%d: %w", idx, err)
-		}
-
-		sourceLog.Debugf("Source yielded %d manifests", len(objects))
-
-		srcNeedRequeue, err := r.manifestApplier.Apply(sourceCtx, client, objects)
-		if err != nil {
-			return requeue, fmt.Errorf("failed to apply source #%d: %w", idx, err)
-		}
-
-		// If one source cannot be completed at this time, continue with the others.
-		if srcNeedRequeue {
-			sourceLog.Debug("Source requires requeuing")
-			requeue = true
+	for _, target := range targets {
+		for idx, ref := range target.Spec.Sources {
+			sourceLog := logger.With("init-target", target.Name, "source-idx", idx)
+			sourceCtx := log.WithLog(ctx, sourceLog)
+
+			src, err := r.sourceFactory.NewForInitSource(sourceCtx, kcp.ClusterNameFromObject(target), ref)
+			if err != nil {
+				return requeue, fmt.Errorf("failed to initialize source #%d from target %s: %w", idx, target.Name, err)
+			}
+
+			objects, err := src.Manifests(lc)
+			if err != nil {
+				return requeue, fmt.Errorf("failed to render source #%d from target %s: %w", idx, target.Name, err)
+			}
+
+			sourceLog.Debugf("Source yielded %d manifests", len(objects))
+
+			srcNeedRequeue, err := r.manifestApplier.Apply(sourceCtx, client, objects)
+			if err != nil {
+				return requeue, fmt.Errorf("failed to apply source #%d from target %s: %w", idx, target.Name, err)
+			}
+
+			// If one source cannot be completed at this time, continue with the others.
+			if srcNeedRequeue {
+				sourceLog.Debug("Source requires requeuing")
+				requeue = true
+			}
 		}
 	}
 

internal/controller/targetcontroller/controller.go

@@ -50,7 +50,7 @@ const (
 	ControllerName = "initagent-target-controller"
 )
 
-type NewInitControllerFunc func(remoteManager mcmanager.Manager, targetProvider initcontroller.InitTargetProvider, initializer kcpcorev1alpha1.LogicalClusterInitializer) error
+type NewInitControllerFunc func(remoteManager mcmanager.Manager, targetProvider initcontroller.InitTargetsProvider, initializer kcpcorev1alpha1.LogicalClusterInitializer) error
 
 type Reconciler struct {
 	// Choose to break good practice of never storing a context in a struct,
@@ -65,8 +65,10 @@ type Reconciler struct {
 	newInitController NewInitControllerFunc
 
 	// A map of cancel funcs for the multicluster managers
-	// that we launch for each InitTarget.
+	// that we launch for each WorkspaceType.
 	ctrlCancels map[string]context.CancelCauseFunc
+	// Tracks which InitTarget names belong to each WorkspaceType key.
+	ctrlTargets map[string]map[string]bool
 	ctrlLock    sync.Mutex
 }
 
@@ -86,6 +88,7 @@ func Add(
 		clusterClient:     clusterClient,
 		newInitController: newInitController,
 		ctrlCancels:       map[string]context.CancelCauseFunc{},
+		ctrlTargets:       map[string]map[string]bool{},
 		ctrlLock:          sync.Mutex{},
 	}
 
@@ -125,10 +128,17 @@ func (r *Reconciler) Reconcile(ctx context.Context, req reconcile.Request) (reco
 func (r *Reconciler) ensureInitController(ctx context.Context, log *zap.SugaredLogger, target *initializationv1alpha1.InitTarget) (reconcile.Result, error) {
 	key := getInitTargetKey(target)
 
-	// controller already exists
+	r.ctrlLock.Lock()
 	if _, exists := r.ctrlCancels[key]; exists {
+		// Controller already exists for this WorkspaceType, just track the target.
+		if r.ctrlTargets[key] == nil {
+			r.ctrlTargets[key] = map[string]bool{}
+		}
+		r.ctrlTargets[key][target.Name] = true
+		r.ctrlLock.Unlock()
 		return reconcile.Result{}, nil
 	}
+	r.ctrlLock.Unlock()
 
 	ctrlog := log.With("ctrlkey", key, "name", target.Name)
 
@@ -148,15 +158,21 @@ func (r *Reconciler) ensureInitController(ctx context.Context, log *zap.SugaredL
 		return reconcile.Result{}, fmt.Errorf("failed to create multicluster manager: %w", err)
 	}
 
-	if err := r.newInitController(mgr, r.newInitTargetProvider(target.Name), initializer); err != nil {
+	if err := r.newInitController(mgr, r.newInitTargetsProvider(key), initializer); err != nil {
 		return reconcile.Result{}, fmt.Errorf("failed to create init controller: %w", err)
 	}
 
 	// Use the global app context so this provider is independent of the reconcile
 	// context, which might get cancelled right after Reconcile() is done.
 	ctrlCtx, ctrlCancel := context.WithCancelCause(r.ctx)
 
+	r.ctrlLock.Lock()
 	r.ctrlCancels[key] = ctrlCancel
+	if r.ctrlTargets[key] == nil {
+		r.ctrlTargets[key] = map[string]bool{}
+	}
+	r.ctrlTargets[key][target.Name] = true
+	r.ctrlLock.Unlock()
 
 	// cleanup when the context is done
 	go func() {
@@ -166,6 +182,7 @@ func (r *Reconciler) ensureInitController(ctx context.Context, log *zap.SugaredL
 		defer r.ctrlLock.Unlock()
 
 		delete(r.ctrlCancels, key)
+		delete(r.ctrlTargets, key)
 	}()
 
 	// time to start the manager
@@ -181,15 +198,22 @@ func (r *Reconciler) ensureInitController(ctx context.Context, log *zap.SugaredL
 
 func (r *Reconciler) cleanupController(log *zap.SugaredLogger, target *initializationv1alpha1.InitTarget) error {
 	key := getInitTargetKey(target)
-	log.Infow("Stopping init controller…", "ctrlkey", key)
+	log.Infow("Removing InitTarget from controller…", "ctrlkey", key, "target", target.Name)
 
 	r.ctrlLock.Lock()
 	defer r.ctrlLock.Unlock()
 
-	cancel, ok := r.ctrlCancels[key]
-	if ok {
-		cancel(errors.New("controller is no longer needed"))
-		delete(r.ctrlCancels, key)
+	if targets, ok := r.ctrlTargets[key]; ok {
+		delete(targets, target.Name)
+		if len(targets) == 0 {
+			// Last target removed, stop the controller.
+			log.Infow("Stopping init controller (last InitTarget removed)…", "ctrlkey", key)
+			if cancel, ok := r.ctrlCancels[key]; ok {
+				cancel(errors.New("controller is no longer needed"))
+				delete(r.ctrlCancels, key)
+			}
+			delete(r.ctrlTargets, key)
+		}
 	}
 
 	return nil
@@ -250,17 +274,32 @@ func (r *Reconciler) createMulticlusterManager(wst *kcptenancyv1alpha1.Workspace
 	return mgr, nil
 }
 
-func (r *Reconciler) newInitTargetProvider(name string) initcontroller.InitTargetProvider {
-	return func(ctx context.Context) (*initializationv1alpha1.InitTarget, error) {
-		target := &initializationv1alpha1.InitTarget{}
-		if err := r.localClient.Get(ctx, types.NamespacedName{Name: name}, target); err != nil {
-			return nil, err
+func (r *Reconciler) newInitTargetsProvider(wstKey string) initcontroller.InitTargetsProvider {
+	return func(ctx context.Context) ([]*initializationv1alpha1.InitTarget, error) {
+		r.ctrlLock.Lock()
+		targetNames := r.ctrlTargets[wstKey]
+		names := make([]string, 0, len(targetNames))
+		for name := range targetNames {
+			names = append(names, name)
 		}
-
-		return target, nil
+		r.ctrlLock.Unlock()
+
+		var targets []*initializationv1alpha1.InitTarget
+		for _, name := range names {
+			target := &initializationv1alpha1.InitTarget{}
+			if err := r.localClient.Get(ctx, types.NamespacedName{Name: name}, target); err != nil {
+				if ctrlruntimeclient.IgnoreNotFound(err) == nil {
+					continue // target was deleted
+				}
+				return nil, err
+			}
+			targets = append(targets, target)
+		}
+		return targets, nil
 	}
 }
 
 func getInitTargetKey(target *initializationv1alpha1.InitTarget) string {
-	return string(target.UID)
+	ref := target.Spec.WorkspaceTypeReference
+	return ref.Path + ":" + ref.Name
 }