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| 1 | +/* |
| 2 | +Copyright 2026. |
| 3 | +
|
| 4 | +Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | +you may not use this file except in compliance with the License. |
| 6 | +You may obtain a copy of the License at |
| 7 | +
|
| 8 | + http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | +
|
| 10 | +Unless required by applicable law or agreed to in writing, software |
| 11 | +distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | +See the License for the specific language governing permissions and |
| 14 | +limitations under the License. |
| 15 | +*/ |
| 16 | + |
| 17 | +// Package remotemcpserver reconciles the discovered tool catalog published in |
| 18 | +// RemoteMCPServer status. |
| 19 | +package remotemcpserver |
| 20 | + |
| 21 | +import ( |
| 22 | + "context" |
| 23 | + "errors" |
| 24 | + "fmt" |
| 25 | + "reflect" |
| 26 | + "slices" |
| 27 | + "strings" |
| 28 | + "time" |
| 29 | + |
| 30 | + dbmodel "github.com/kagent-dev/kagent/go/api/database" |
| 31 | + "github.com/kagent-dev/kagent/go/api/v1alpha3" |
| 32 | + toolservice "github.com/kagent-dev/kagent/go/core/internal/service/tool" |
| 33 | + corev1 "k8s.io/api/core/v1" |
| 34 | + apierrors "k8s.io/apimachinery/pkg/api/errors" |
| 35 | + apiMeta "k8s.io/apimachinery/pkg/api/meta" |
| 36 | + metav1 "k8s.io/apimachinery/pkg/apis/meta/v1" |
| 37 | + "k8s.io/apimachinery/pkg/types" |
| 38 | + ctrl "sigs.k8s.io/controller-runtime" |
| 39 | + "sigs.k8s.io/controller-runtime/pkg/builder" |
| 40 | + "sigs.k8s.io/controller-runtime/pkg/client" |
| 41 | + "sigs.k8s.io/controller-runtime/pkg/handler" |
| 42 | + "sigs.k8s.io/controller-runtime/pkg/predicate" |
| 43 | + "sigs.k8s.io/controller-runtime/pkg/reconcile" |
| 44 | +) |
| 45 | + |
| 46 | +const ( |
| 47 | + conditionAccepted = "Accepted" |
| 48 | + remoteGroupKind = "RemoteMCPServer.kagent.dev" |
| 49 | + refreshInterval = 5 * time.Minute |
| 50 | +) |
| 51 | + |
| 52 | +// ToolDiscoverer returns the tools currently advertised by one MCP server. |
| 53 | +type ToolDiscoverer interface { |
| 54 | + ListTools(context.Context, toolservice.MCPServerRef) ([]toolservice.MCPAppTool, error) |
| 55 | +} |
| 56 | + |
| 57 | +// CatalogStore keeps the gRPC ToolService catalog aligned with Kubernetes status. |
| 58 | +// RemoteMCPServer status remains the source used by harness compilers, while the |
| 59 | +// database projection serves list RPCs without making those RPCs perform discovery. |
| 60 | +type CatalogStore interface { |
| 61 | + StoreToolServer(context.Context, *dbmodel.ToolServer) (*dbmodel.ToolServer, error) |
| 62 | + RefreshToolsForServer(context.Context, string, string, ...*v1alpha3.MCPTool) error |
| 63 | + DeleteToolsForServer(context.Context, string, string) error |
| 64 | + DeleteToolServer(context.Context, string, string) error |
| 65 | +} |
| 66 | + |
| 67 | +// Reconciler publishes RemoteMCPServer discovery results to its status. |
| 68 | +type Reconciler struct { |
| 69 | + client client.Client |
| 70 | + discoverer ToolDiscoverer |
| 71 | + catalog CatalogStore |
| 72 | +} |
| 73 | + |
| 74 | +func New(client client.Client, discoverer ToolDiscoverer, catalog CatalogStore) *Reconciler { |
| 75 | + return &Reconciler{client: client, discoverer: discoverer, catalog: catalog} |
| 76 | +} |
| 77 | + |
| 78 | +func (r *Reconciler) SetupWithManager(manager ctrl.Manager) error { |
| 79 | + return ctrl.NewControllerManagedBy(manager). |
| 80 | + For(&v1alpha3.RemoteMCPServer{}, builder.WithPredicates(predicate.GenerationChangedPredicate{})). |
| 81 | + Watches(&corev1.Secret{}, handler.EnqueueRequestsFromMapFunc(r.requestsForDependency)). |
| 82 | + Watches(&corev1.ConfigMap{}, handler.EnqueueRequestsFromMapFunc(r.requestsForDependency)). |
| 83 | + Complete(r) |
| 84 | +} |
| 85 | + |
| 86 | +func (r *Reconciler) Reconcile(ctx context.Context, request reconcile.Request) (reconcile.Result, error) { |
| 87 | + server := &v1alpha3.RemoteMCPServer{} |
| 88 | + if err := r.client.Get(ctx, request.NamespacedName, server); err != nil { |
| 89 | + if !apierrors.IsNotFound(err) { |
| 90 | + return reconcile.Result{}, err |
| 91 | + } |
| 92 | + return reconcile.Result{}, r.deleteCatalog(ctx, request.String()) |
| 93 | + } |
| 94 | + |
| 95 | + tools, err := r.discoverer.ListTools(ctx, toolservice.MCPServerRef{ |
| 96 | + Ref: request.NamespacedName, GroupKind: remoteGroupKind, |
| 97 | + }) |
| 98 | + if err != nil { |
| 99 | + statusErr := r.updateStatus(ctx, server, nil, metav1.ConditionFalse, "DiscoveryFailed", err.Error()) |
| 100 | + catalogErr := r.updateCatalog(ctx, server, nil, false) |
| 101 | + return reconcile.Result{}, errors.Join( |
| 102 | + fmt.Errorf("discover RemoteMCPServer tools: %w", err), |
| 103 | + wrapError("update RemoteMCPServer discovery failure", statusErr), |
| 104 | + wrapError("clear RemoteMCPServer tool catalog", catalogErr), |
| 105 | + ) |
| 106 | + } |
| 107 | + |
| 108 | + discovered, err := normalizeTools(tools) |
| 109 | + if err != nil { |
| 110 | + statusErr := r.updateStatus(ctx, server, nil, metav1.ConditionFalse, "InvalidDiscovery", err.Error()) |
| 111 | + catalogErr := r.updateCatalog(ctx, server, nil, false) |
| 112 | + return reconcile.Result{}, errors.Join( |
| 113 | + err, |
| 114 | + wrapError("update invalid RemoteMCPServer discovery", statusErr), |
| 115 | + wrapError("clear invalid RemoteMCPServer tool catalog", catalogErr), |
| 116 | + ) |
| 117 | + } |
| 118 | + message := fmt.Sprintf("Discovered %d MCP tools", len(discovered)) |
| 119 | + if err := r.updateStatus(ctx, server, discovered, metav1.ConditionTrue, "DiscoverySucceeded", message); err != nil { |
| 120 | + return reconcile.Result{}, fmt.Errorf("update RemoteMCPServer discovery status: %w", err) |
| 121 | + } |
| 122 | + if err := r.updateCatalog(ctx, server, discovered, true); err != nil { |
| 123 | + return reconcile.Result{}, fmt.Errorf("update RemoteMCPServer tool catalog: %w", err) |
| 124 | + } |
| 125 | + return reconcile.Result{RequeueAfter: refreshInterval}, nil |
| 126 | +} |
| 127 | + |
| 128 | +func (r *Reconciler) updateCatalog(ctx context.Context, server *v1alpha3.RemoteMCPServer, tools []*v1alpha3.MCPTool, connected bool) error { |
| 129 | + name := client.ObjectKeyFromObject(server).String() |
| 130 | + var lastConnected *time.Time |
| 131 | + if connected { |
| 132 | + now := time.Now().UTC() |
| 133 | + lastConnected = &now |
| 134 | + } |
| 135 | + if _, err := r.catalog.StoreToolServer(ctx, &dbmodel.ToolServer{ |
| 136 | + Name: name, GroupKind: remoteGroupKind, Description: server.Spec.Description, LastConnected: lastConnected, |
| 137 | + }); err != nil { |
| 138 | + return fmt.Errorf("store server: %w", err) |
| 139 | + } |
| 140 | + if err := r.catalog.RefreshToolsForServer(ctx, name, remoteGroupKind, tools...); err != nil { |
| 141 | + return fmt.Errorf("refresh tools: %w", err) |
| 142 | + } |
| 143 | + return nil |
| 144 | +} |
| 145 | + |
| 146 | +func (r *Reconciler) deleteCatalog(ctx context.Context, name string) error { |
| 147 | + return errors.Join( |
| 148 | + wrapError("delete tools", r.catalog.DeleteToolsForServer(ctx, name, remoteGroupKind)), |
| 149 | + wrapError("delete server", r.catalog.DeleteToolServer(ctx, name, remoteGroupKind)), |
| 150 | + ) |
| 151 | +} |
| 152 | + |
| 153 | +func wrapError(action string, err error) error { |
| 154 | + if err == nil { |
| 155 | + return nil |
| 156 | + } |
| 157 | + return fmt.Errorf("%s: %w", action, err) |
| 158 | +} |
| 159 | + |
| 160 | +func normalizeTools(tools []toolservice.MCPAppTool) ([]*v1alpha3.MCPTool, error) { |
| 161 | + discovered := make([]*v1alpha3.MCPTool, 0, len(tools)) |
| 162 | + seen := make(map[string]struct{}, len(tools)) |
| 163 | + for _, tool := range tools { |
| 164 | + if strings.TrimSpace(tool.Name) == "" { |
| 165 | + return nil, fmt.Errorf("MCP discovery returned a tool with an empty name") |
| 166 | + } |
| 167 | + if _, exists := seen[tool.Name]; exists { |
| 168 | + return nil, fmt.Errorf("MCP discovery returned duplicate tool %q", tool.Name) |
| 169 | + } |
| 170 | + seen[tool.Name] = struct{}{} |
| 171 | + discovered = append(discovered, &v1alpha3.MCPTool{Name: tool.Name, Description: tool.Description}) |
| 172 | + } |
| 173 | + slices.SortFunc(discovered, func(a, b *v1alpha3.MCPTool) int { |
| 174 | + return strings.Compare(a.Name, b.Name) |
| 175 | + }) |
| 176 | + return discovered, nil |
| 177 | +} |
| 178 | + |
| 179 | +func (r *Reconciler) updateStatus( |
| 180 | + ctx context.Context, |
| 181 | + server *v1alpha3.RemoteMCPServer, |
| 182 | + tools []*v1alpha3.MCPTool, |
| 183 | + conditionStatus metav1.ConditionStatus, |
| 184 | + reason string, |
| 185 | + message string, |
| 186 | +) error { |
| 187 | + original := server.DeepCopy() |
| 188 | + server.Status.ObservedGeneration = server.Generation |
| 189 | + server.Status.DiscoveredTools = tools |
| 190 | + apiMeta.SetStatusCondition(&server.Status.Conditions, metav1.Condition{ |
| 191 | + Type: conditionAccepted, Status: conditionStatus, Reason: reason, Message: message, |
| 192 | + ObservedGeneration: server.Generation, |
| 193 | + }) |
| 194 | + if reflect.DeepEqual(original.Status, server.Status) { |
| 195 | + return nil |
| 196 | + } |
| 197 | + return r.client.Status().Patch(ctx, server, client.MergeFrom(original)) |
| 198 | +} |
| 199 | + |
| 200 | +func (r *Reconciler) requestsForDependency(ctx context.Context, object client.Object) []reconcile.Request { |
| 201 | + servers := &v1alpha3.RemoteMCPServerList{} |
| 202 | + if err := r.client.List(ctx, servers, client.InNamespace(object.GetNamespace())); err != nil { |
| 203 | + return nil |
| 204 | + } |
| 205 | + requests := make([]reconcile.Request, 0) |
| 206 | + for i := range servers.Items { |
| 207 | + server := &servers.Items[i] |
| 208 | + if referencesDependency(server, object) { |
| 209 | + requests = append(requests, reconcile.Request{NamespacedName: types.NamespacedName{ |
| 210 | + Namespace: server.Namespace, Name: server.Name, |
| 211 | + }}) |
| 212 | + } |
| 213 | + } |
| 214 | + return requests |
| 215 | +} |
| 216 | + |
| 217 | +func referencesDependency(server *v1alpha3.RemoteMCPServer, object client.Object) bool { |
| 218 | + switch object.(type) { |
| 219 | + case *corev1.Secret: |
| 220 | + if server.Spec.TLS != nil && server.Spec.TLS.CACertSecretRef == object.GetName() { |
| 221 | + return true |
| 222 | + } |
| 223 | + for i := range server.Spec.HeadersFrom { |
| 224 | + from := server.Spec.HeadersFrom[i].ValueFrom |
| 225 | + if from != nil && from.Type == v1alpha3.SecretValueSource && from.Name == object.GetName() { |
| 226 | + return true |
| 227 | + } |
| 228 | + } |
| 229 | + case *corev1.ConfigMap: |
| 230 | + for i := range server.Spec.HeadersFrom { |
| 231 | + from := server.Spec.HeadersFrom[i].ValueFrom |
| 232 | + if from != nil && from.Type == v1alpha3.ConfigMapValueSource && from.Name == object.GetName() { |
| 233 | + return true |
| 234 | + } |
| 235 | + } |
| 236 | + } |
| 237 | + return false |
| 238 | +} |
| 239 | + |
| 240 | +var _ reconcile.Reconciler = (*Reconciler)(nil) |
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