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yrobla
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Add CRD type changes for horizontal scaling (#4363)
* Add CRD type changes for horizontal scaling Add SessionStorageConfig struct and scaling fields to MCPServer and VirtualMCPServer CRDs as the foundation for horizontal scaling support. - Add SessionStorageConfig struct with Provider, Address, DB, KeyPrefix, and PasswordRef fields; CEL rule enforces address is required for redis - Add Replicas *int32, BackendReplicas *int32, SessionStorage to MCPServerSpec - Add Replicas *int32, SessionStorage to VirtualMCPServerSpec - Nil pointer fields allow HPA to manage replicas without operator interference - Regenerate zz_generated.deepcopy.go and CRD manifests Closes: #4206 * rebase merge conflicts and fixes from review --------- Co-authored-by: taskbot <taskbot@users.noreply.github.com>
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‎cmd/thv-operator/api/v1alpha1/mcpserver_types.go‎

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@@ -226,6 +226,29 @@ type MCPServerSpec struct {
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// +kubebuilder:default=ClientIP
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// +optional
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SessionAffinity string `json:"sessionAffinity,omitempty"`
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// Replicas is the desired number of proxy runner (thv run) pod replicas.
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// MCPServer creates two separate Deployments: one for the proxy runner and one
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// for the MCP server backend. This field controls the proxy runner Deployment.
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// When nil, the operator does not set Deployment.Spec.Replicas, leaving replica
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// management to an HPA or other external controller.
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// +kubebuilder:validation:Minimum=0
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// +optional
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Replicas *int32 `json:"replicas,omitempty"`
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// BackendReplicas is the desired number of MCP server backend pod replicas.
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// This controls the backend Deployment (the MCP server container itself),
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// independent of the proxy runner controlled by Replicas.
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// When nil, the operator does not set Deployment.Spec.Replicas, leaving replica
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// management to an HPA or other external controller.
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// +kubebuilder:validation:Minimum=0
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// +optional
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BackendReplicas *int32 `json:"backendReplicas,omitempty"`
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// SessionStorage configures session storage for stateful horizontal scaling.
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// When nil, no session storage is configured.
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// +optional
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SessionStorage *SessionStorageConfig `json:"sessionStorage,omitempty"`
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}
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// ResourceOverrides defines overrides for annotations and labels on created resources
@@ -338,6 +361,44 @@ type SecretRef struct {
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TargetEnvName string `json:"targetEnvName,omitempty"`
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}
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// SessionStorageConfig defines session storage configuration for horizontal scaling.
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//
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// This is the CRD/K8s-aware surface: it uses SecretKeyRef for secret resolution.
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// The reconciler resolves PasswordRef to a plain string and builds a
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// session.RedisConfig (pkg/transport/session) for the actual storage backend.
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//
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// TODO: Add a corresponding SessionStorageConfig to pkg/vmcp/config.Config so the
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// vMCP process receives session storage config through the existing config injection
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// path (same as Optimizer and Audit). The CRD type will remain separate because
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// PasswordRef is K8s-specific and gets resolved away before the config-pkg type.
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//
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// +kubebuilder:validation:XValidation:rule="self.provider == 'redis' ? has(self.address) : true",message="address is required"
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type SessionStorageConfig struct {
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// Provider is the session storage backend type
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// +kubebuilder:validation:Enum=memory;redis
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// +kubebuilder:validation:Required
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Provider string `json:"provider"`
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// Address is the Redis server address (required when provider is redis)
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// +kubebuilder:validation:MinLength=1
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// +optional
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Address string `json:"address,omitempty"`
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// DB is the Redis database number
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// +kubebuilder:validation:Minimum=0
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// +kubebuilder:default=0
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// +optional
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DB int32 `json:"db,omitempty"`
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// KeyPrefix is an optional prefix for all Redis keys used by ToolHive
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// +optional
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KeyPrefix string `json:"keyPrefix,omitempty"`
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// PasswordRef is a reference to a Secret key containing the Redis password
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// +optional
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PasswordRef *SecretKeyRef `json:"passwordRef,omitempty"`
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}
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// Permission profile types
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const (
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// PermissionProfileTypeBuiltin is the type for built-in permission profiles

‎cmd/thv-operator/api/v1alpha1/mcpserver_types_test.go‎

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// SPDX-FileCopyrightText: Copyright 2025 Stacklok, Inc.
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// SPDX-License-Identifier: Apache-2.0
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package v1alpha1
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import (
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"encoding/json"
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"testing"
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"github.com/stretchr/testify/assert"
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"github.com/stretchr/testify/require"
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)
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func TestSessionStorageConfigJSONRoundtrip(t *testing.T) {
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t.Parallel()
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tests := []struct {
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name string
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input SessionStorageConfig
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wantJSON string
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}{
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{
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name: "memory provider",
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input: SessionStorageConfig{
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Provider: "memory",
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},
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wantJSON: `{"provider":"memory"}`,
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},
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{
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name: "redis provider with address",
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input: SessionStorageConfig{
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Provider: "redis",
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Address: "redis:6379",
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},
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wantJSON: `{"provider":"redis","address":"redis:6379"}`,
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},
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{
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name: "redis provider with all fields",
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input: SessionStorageConfig{
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Provider: "redis",
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Address: "redis:6379",
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DB: 1,
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KeyPrefix: "thv:",
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},
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wantJSON: `{"provider":"redis","address":"redis:6379","db":1,"keyPrefix":"thv:"}`,
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},
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{
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name: "db zero is omitted",
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input: SessionStorageConfig{
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Provider: "redis",
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Address: "redis:6379",
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DB: 0,
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},
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wantJSON: `{"provider":"redis","address":"redis:6379"}`,
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},
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}
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for _, tc := range tests {
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t.Run(tc.name, func(t *testing.T) {
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t.Parallel()
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b, err := json.Marshal(tc.input)
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require.NoError(t, err)
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assert.JSONEq(t, tc.wantJSON, string(b))
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})
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}
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}
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func TestMCPServerSpecScalingFieldsJSONRoundtrip(t *testing.T) {
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t.Parallel()
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replicas := int32(3)
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backendReplicas := int32(2)
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tests := []struct {
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name string
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spec MCPServerSpec
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wantKeys []string
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wantAbsent []string
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}{
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{
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name: "nil replicas are omitted",
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spec: MCPServerSpec{Image: "example/mcp:latest"},
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wantAbsent: []string{`"replicas"`, `"backendReplicas"`, `"sessionStorage"`},
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},
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{
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name: "set replicas are serialized",
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spec: MCPServerSpec{
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Image: "example/mcp:latest",
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Replicas: &replicas,
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BackendReplicas: &backendReplicas,
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},
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wantKeys: []string{`"replicas":3`, `"backendReplicas":2`},
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},
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{
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name: "sessionStorage is serialized when set",
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spec: MCPServerSpec{
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Image: "example/mcp:latest",
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SessionStorage: &SessionStorageConfig{
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Provider: "redis",
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Address: "redis:6379",
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},
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},
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wantKeys: []string{`"sessionStorage"`, `"provider":"redis"`},
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},
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}
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for _, tc := range tests {
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t.Run(tc.name, func(t *testing.T) {
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t.Parallel()
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b, err := json.Marshal(tc.spec)
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require.NoError(t, err)
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out := string(b)
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for _, key := range tc.wantKeys {
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assert.Contains(t, out, key)
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}
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for _, key := range tc.wantAbsent {
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assert.NotContains(t, out, key)
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}
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})
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}
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}

‎cmd/thv-operator/api/v1alpha1/virtualmcpserver_types.go‎

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@@ -82,6 +82,21 @@ type VirtualMCPServerSpec struct {
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// When nil, IncomingAuth uses an external IDP and behavior is unchanged.
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// +optional
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AuthServerConfig *EmbeddedAuthServerConfig `json:"authServerConfig,omitempty"`
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// Replicas is the desired number of vMCP pod replicas.
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// VirtualMCPServer creates a single Deployment for the vMCP aggregator process,
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// so there is only one replicas field (unlike MCPServer which has separate
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// Replicas and BackendReplicas for its two Deployments).
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// When nil, the operator does not set Deployment.Spec.Replicas, leaving replica
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// management to an HPA or other external controller.
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// +kubebuilder:validation:Minimum=0
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// +optional
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Replicas *int32 `json:"replicas,omitempty"`
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// SessionStorage configures session storage for stateful horizontal scaling.
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// When nil, no session storage is configured.
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// +optional
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SessionStorage *SessionStorageConfig `json:"sessionStorage,omitempty"`
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}
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// EmbeddingServerRef references an existing EmbeddingServer resource by name.

‎cmd/thv-operator/api/v1alpha1/virtualmcpserver_types_test.go‎

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package v1alpha1
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import (
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"encoding/json"
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"testing"
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"github.com/stretchr/testify/assert"
@@ -479,3 +480,58 @@ func TestValidateEmbeddingServer(t *testing.T) {
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})
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}
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}
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func TestVirtualMCPServerSpecScalingFieldsJSONRoundtrip(t *testing.T) {
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t.Parallel()
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replicas := int32(2)
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tests := []struct {
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name string
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spec VirtualMCPServerSpec
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wantKeys []string
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wantAbsent []string
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}{
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{
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name: "nil replicas are omitted",
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spec: VirtualMCPServerSpec{
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IncomingAuth: &IncomingAuthConfig{Type: "anonymous"},
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},
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wantAbsent: []string{`"replicas"`, `"sessionStorage"`},
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},
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{
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name: "set replicas are serialized",
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spec: VirtualMCPServerSpec{
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IncomingAuth: &IncomingAuthConfig{Type: "anonymous"},
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Replicas: &replicas,
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},
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wantKeys: []string{`"replicas":2`},
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},
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{
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name: "sessionStorage is serialized when set",
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spec: VirtualMCPServerSpec{
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IncomingAuth: &IncomingAuthConfig{Type: "anonymous"},
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SessionStorage: &SessionStorageConfig{
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Provider: "redis",
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Address: "redis:6379",
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},
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},
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wantKeys: []string{`"sessionStorage"`, `"provider":"redis"`},
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},
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}
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for _, tc := range tests {
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t.Run(tc.name, func(t *testing.T) {
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t.Parallel()
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b, err := json.Marshal(tc.spec)
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require.NoError(t, err)
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out := string(b)
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for _, key := range tc.wantKeys {
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assert.Contains(t, out, key)
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}
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for _, key := range tc.wantAbsent {
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assert.NotContains(t, out, key)
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}
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})
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}
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}

‎cmd/thv-operator/api/v1alpha1/zz_generated.deepcopy.go‎

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