feat: Support hot reloading of MCP operation files #1959
+719
−47
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,282 @@ | ||
| package integration | ||
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| import ( | ||
| "encoding/json" | ||
| "os" | ||
| "testing" | ||
| "time" | ||
|
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| "github.com/mark3labs/mcp-go/mcp" | ||
| "github.com/stretchr/testify/assert" | ||
| "github.com/stretchr/testify/require" | ||
| "github.com/wundergraph/cosmo/router-tests/testenv" | ||
| "github.com/wundergraph/cosmo/router/core" | ||
| "github.com/wundergraph/cosmo/router/pkg/config" | ||
| "go.uber.org/goleak" | ||
| ) | ||
|
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| func TestMCPOperationHotReload(t *testing.T) { | ||
| t.Parallel() | ||
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| t.Run("List Updated User Operations On Addition and Removal", func(t *testing.T) { | ||
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| operationsDir := t.TempDir() | ||
| storageProviderId := "mcp_hot_reload_test_id" | ||
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| testenv.Run(t, &testenv.Config{ | ||
| MCP: config.MCPConfiguration{ | ||
| Enabled: true, | ||
| Storage: config.MCPStorageConfig{ | ||
| ProviderID: storageProviderId, | ||
| }, | ||
| HotReloadConfig: config.MCPOperationsHotReloadConfig{ | ||
| Enabled: true, | ||
| Interval: 5 * time.Second, | ||
| }, | ||
| }, | ||
| RouterOptions: []core.Option{ | ||
| core.WithStorageProviders(config.StorageProviders{ | ||
| FileSystem: []config.FileSystemStorageProvider{ | ||
| { | ||
| ID: storageProviderId, | ||
| Path: operationsDir, | ||
| }, | ||
| }, | ||
| }), | ||
| }, | ||
| }, func(t *testing.T, xEnv *testenv.Environment) { | ||
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| toolsRequest := mcp.ListToolsRequest{} | ||
| resp, err := xEnv.MCPClient.ListTools(xEnv.Context, toolsRequest) | ||
| require.NoError(t, err) | ||
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| initialToolsCount := len(resp.Tools) | ||
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| filePath := operationsDir + "/main.graphql" | ||
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| // write mcp operation content | ||
| err = os.WriteFile(filePath, []byte("query getEmployeeNotes($id: Int!) {\nemployee(id: $id) {\nid\nnotes\n}\n}"), 0644) | ||
| assert.NoError(t, err) | ||
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| require.EventuallyWithT(t, func(t *assert.CollectT) { | ||
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| resp, err := xEnv.MCPClient.ListTools(xEnv.Context, toolsRequest) | ||
| assert.NoError(t, err) | ||
| assert.Len(t, resp.Tools, initialToolsCount+1) | ||
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| // verity getEmployeeNotes operation is present | ||
| require.Contains(t, resp.Tools, mcp.Tool{ | ||
| Name: "execute_operation_get_employee_notes", | ||
| Description: "Executes the GraphQL operation 'getEmployeeNotes' of type query.", | ||
| InputSchema: mcp.ToolInputSchema{ | ||
| Type: "object", | ||
| Properties: map[string]interface{}{"id": map[string]interface{}{"type": "integer"}}, | ||
| Required: []string{"id"}, | ||
| }, | ||
| RawInputSchema: json.RawMessage(nil), | ||
| Annotations: mcp.ToolAnnotation{ | ||
| Title: "Execute operation getEmployeeNotes", | ||
| ReadOnlyHint: mcp.ToBoolPtr(true), | ||
| IdempotentHint: mcp.ToBoolPtr(true), | ||
| OpenWorldHint: mcp.ToBoolPtr(true), | ||
| }, | ||
| }) | ||
| }, 15*time.Second, 250*time.Millisecond) | ||
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| err = os.Remove(filePath) | ||
| assert.NoError(t, err) | ||
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| assert.EventuallyWithT(t, func(t *assert.CollectT) { | ||
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| resp, err = xEnv.MCPClient.ListTools(xEnv.Context, toolsRequest) | ||
| assert.NoError(t, err) | ||
| assert.Len(t, resp.Tools, initialToolsCount) | ||
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| // verity getEmployeeNotes operation tool is properly removed | ||
| require.NotContains(t, resp.Tools, mcp.Tool{ | ||
| Name: "execute_operation_get_employee_notes", | ||
| Description: "Executes the GraphQL operation 'getEmployeeNotes' of type query.", | ||
| InputSchema: mcp.ToolInputSchema{ | ||
| Type: "object", | ||
| Properties: map[string]interface{}{"id": map[string]interface{}{"type": "integer"}}, | ||
| Required: []string{"id"}, | ||
| }, | ||
| RawInputSchema: json.RawMessage(nil), | ||
| Annotations: mcp.ToolAnnotation{ | ||
| Title: "Execute operation getEmployeeNotes", | ||
| ReadOnlyHint: mcp.ToBoolPtr(true), | ||
| IdempotentHint: mcp.ToBoolPtr(true), | ||
| OpenWorldHint: mcp.ToBoolPtr(true), | ||
| }, | ||
| }) | ||
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| }, 15*time.Second, 250*time.Millisecond) | ||
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| }) | ||
| }) | ||
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| t.Run("List Updated User Operations On Content Update", func(t *testing.T) { | ||
| operationsDir := t.TempDir() | ||
| storageProviderId := "mcp_hot_reload_test_id" | ||
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| testenv.Run(t, &testenv.Config{ | ||
| MCP: config.MCPConfiguration{ | ||
| Enabled: true, | ||
| Storage: config.MCPStorageConfig{ | ||
| ProviderID: storageProviderId, | ||
| }, | ||
| HotReloadConfig: config.MCPOperationsHotReloadConfig{ | ||
| Enabled: true, | ||
| Interval: 5 * time.Second, | ||
| }, | ||
| }, | ||
| RouterOptions: []core.Option{ | ||
| core.WithStorageProviders(config.StorageProviders{ | ||
| FileSystem: []config.FileSystemStorageProvider{ | ||
| { | ||
| ID: storageProviderId, | ||
| Path: operationsDir, | ||
| }, | ||
| }, | ||
| }), | ||
| }, | ||
| }, func(t *testing.T, xEnv *testenv.Environment) { | ||
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| filePath := operationsDir + "/main.graphql" | ||
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| // write mcp operation content | ||
| err := os.WriteFile(filePath, []byte("query getEmployeeNotes($id: Int!) {\nemployee(id: $id) {\nid\nnotes\n}\n}"), 0644) | ||
| assert.NoError(t, err) | ||
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| require.EventuallyWithT(t, func(t *assert.CollectT) { | ||
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| toolsRequest := mcp.ListToolsRequest{} | ||
| resp, err := xEnv.MCPClient.ListTools(xEnv.Context, toolsRequest) | ||
| assert.NoError(t, err) | ||
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| // verity getEmployeeNotes operation is present | ||
| require.Contains(t, resp.Tools, mcp.Tool{ | ||
| Name: "execute_operation_get_employee_notes", | ||
| Description: "Executes the GraphQL operation 'getEmployeeNotes' of type query.", | ||
| InputSchema: mcp.ToolInputSchema{ | ||
| Type: "object", | ||
| Properties: map[string]interface{}{"id": map[string]interface{}{"type": "integer"}}, | ||
| Required: []string{"id"}, | ||
| }, | ||
| RawInputSchema: json.RawMessage(nil), | ||
| Annotations: mcp.ToolAnnotation{ | ||
| Title: "Execute operation getEmployeeNotes", | ||
| ReadOnlyHint: mcp.ToBoolPtr(true), | ||
| IdempotentHint: mcp.ToBoolPtr(true), | ||
| OpenWorldHint: mcp.ToBoolPtr(true), | ||
| }, | ||
| }) | ||
| }, 15*time.Second, 250*time.Millisecond) | ||
|
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| // update mcp operation content | ||
| err = os.WriteFile(filePath, []byte("\nquery getEmployeeNotesUpdatedTitle($id: Int!) {\nemployee(id: $id) {\nid\nnotes\n}\n}"), 0644) | ||
| assert.NoError(t, err) | ||
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| require.EventuallyWithT(t, func(t *assert.CollectT) { | ||
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| toolsRequest := mcp.ListToolsRequest{} | ||
| resp, err := xEnv.MCPClient.ListTools(xEnv.Context, toolsRequest) | ||
| assert.NoError(t, err) | ||
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| // verity getEmployeeNotesUpdatedTitle operation is present | ||
| require.Contains(t, resp.Tools, mcp.Tool{ | ||
| Name: "execute_operation_get_employee_notes_updated_title", | ||
| Description: "Executes the GraphQL operation 'getEmployeeNotesUpdatedTitle' of type query.", | ||
| InputSchema: mcp.ToolInputSchema{ | ||
| Type: "object", | ||
| Properties: map[string]interface{}{"id": map[string]interface{}{"type": "integer"}}, | ||
| Required: []string{"id"}, | ||
| }, | ||
| RawInputSchema: json.RawMessage(nil), | ||
| Annotations: mcp.ToolAnnotation{ | ||
| Title: "Execute operation getEmployeeNotesUpdatedTitle", | ||
| ReadOnlyHint: mcp.ToBoolPtr(true), | ||
| IdempotentHint: mcp.ToBoolPtr(true), | ||
| OpenWorldHint: mcp.ToBoolPtr(true), | ||
| }, | ||
| }) | ||
| }, 15*time.Second, 250*time.Millisecond) | ||
| }) | ||
| }) | ||
| } | ||
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| func TestShutDownMCPGoRoutineLeaks(t *testing.T) { | ||
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| defer goleak.VerifyNone(t, | ||
| goleak.IgnoreTopFunction("github.com/hashicorp/consul/sdk/freeport.checkFreedPorts"), // Freeport, spawned by init | ||
| goleak.IgnoreAnyFunction("net/http.(*conn).serve"), // HTTPTest server I can't close if I want to keep the problematic goroutine open for the test | ||
| ) | ||
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| operationsDir := t.TempDir() | ||
| storageProviderId := "mcp_hot_reload_test_id" | ||
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| xEnv, err := testenv.CreateTestEnv(t, &testenv.Config{ | ||
| MCP: config.MCPConfiguration{ | ||
| Enabled: true, | ||
| Storage: config.MCPStorageConfig{ | ||
| ProviderID: storageProviderId, | ||
| }, | ||
| HotReloadConfig: config.MCPOperationsHotReloadConfig{ | ||
| Enabled: true, | ||
| Interval: 5 * time.Second, | ||
| }, | ||
| }, | ||
| RouterOptions: []core.Option{ | ||
| core.WithStorageProviders(config.StorageProviders{ | ||
| FileSystem: []config.FileSystemStorageProvider{ | ||
| { | ||
| ID: storageProviderId, | ||
| Path: operationsDir, | ||
| }, | ||
| }, | ||
| }), | ||
| }, | ||
| }) | ||
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| require.NoError(t, err) | ||
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| filePath := operationsDir + "/main.graphql" | ||
| // write mcp operation content | ||
| err = os.WriteFile(filePath, []byte("query getEmployeeNotes($id: Int!) {\nemployee(id: $id) {\nid\nnotes\n}\n}"), 0644) | ||
| assert.NoError(t, err) | ||
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| // Verify GoRoutines are properly setup for Hot Reloading | ||
| require.EventuallyWithT(t, func(t *assert.CollectT) { | ||
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| toolsRequest := mcp.ListToolsRequest{} | ||
| resp, err := xEnv.MCPClient.ListTools(xEnv.Context, toolsRequest) | ||
| assert.NoError(t, err) | ||
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| require.Contains(t, resp.Tools, mcp.Tool{ | ||
| Name: "execute_operation_get_employee_notes", | ||
| Description: "Executes the GraphQL operation 'getEmployeeNotes' of type query.", | ||
| InputSchema: mcp.ToolInputSchema{ | ||
| Type: "object", | ||
| Properties: map[string]interface{}{"id": map[string]interface{}{"type": "integer"}}, | ||
| Required: []string{"id"}, | ||
| }, | ||
| RawInputSchema: json.RawMessage(nil), | ||
| Annotations: mcp.ToolAnnotation{ | ||
| Title: "Execute operation getEmployeeNotes", | ||
| ReadOnlyHint: mcp.ToBoolPtr(true), | ||
| IdempotentHint: mcp.ToBoolPtr(true), | ||
| OpenWorldHint: mcp.ToBoolPtr(true), | ||
| }, | ||
| }) | ||
| }, 15*time.Second, 250*time.Millisecond) | ||
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| xEnv.Shutdown() | ||
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| toolsRequest := mcp.ListToolsRequest{} | ||
| resp, err := xEnv.MCPClient.ListTools(xEnv.Context, toolsRequest) | ||
| if assert.Error(t, err) { | ||
| require.ErrorIs(t, err, testenv.ErrEnvironmentClosed) | ||
| } | ||
| require.Nil(t, resp) | ||
|
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| } | ||
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| Original file line number | Diff line number | Diff line change | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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@@ -1079,9 +1079,22 @@ func (s *graphServer) buildGraphMux(ctx context.Context, | |||||||||||||||||
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| // We support the MCP only on the base graph. Feature flags are not supported yet. | ||||||||||||||||||
| if featureFlagName == "" && s.mcpServer != nil { | ||||||||||||||||||
| if mErr := s.mcpServer.Reload(ctx, executor.ClientSchema); mErr != nil { | ||||||||||||||||||
| return nil, fmt.Errorf("failed to reload MCP server: %w", mErr) | ||||||||||||||||||
| } | ||||||||||||||||||
| go func() { | ||||||||||||||||||
| for { | ||||||||||||||||||
| select { | ||||||||||||||||||
| case <-s.mcpServer.ReloadOperationsChannel(): | ||||||||||||||||||
| s.logger.Log(zap.InfoLevel, "Reloading mcp server!") | ||||||||||||||||||
| if mErr := s.mcpServer.Reload(ctx, executor.ClientSchema); mErr != nil { | ||||||||||||||||||
| return | ||||||||||||||||||
| } | ||||||||||||||||||
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Comment on lines
+1221
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+1223
There was a problem hiding this comment. Handle reload errors without terminating the goroutine If Consider logging the error and continuing to listen for reload signals: case <-s.mcpServer.ReloadOperationsChannel():
s.logger.Log(zap.InfoLevel, "Reloading mcp server!")
if mErr := s.mcpServer.Reload(ctx, executor.ClientSchema); mErr != nil {
- return
+ s.logger.Error("Failed to reload MCP server", zap.Error(mErr))
}📝 Committable suggestion
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There was a problem hiding this comment. Hi @endigma, Please let me know if it is the expected behaviour to further retry mcpServer reload operations even after reload failure. There was a problem hiding this comment.
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| case <-ctx.Done(): | ||||||||||||||||||
| return | ||||||||||||||||||
| } | ||||||||||||||||||
| } | ||||||||||||||||||
| }() | ||||||||||||||||||
| } | ||||||||||||||||||
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| if s.Config.cacheWarmup != nil && s.Config.cacheWarmup.Enabled { | ||||||||||||||||||
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storageProviderIdshould beIDand it seems the same across all subtests so can we move it out to test scope?There was a problem hiding this comment.
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Yes, we can.