Fix feature flag and telemetry export endpoints

- Change feature flag endpoint to use NODEJS client type
- Fix telemetry endpoints to /telemetry-ext and /telemetry-unauth
- Update payload to match proto with system_configuration
- Add shared buildUrl utility for protocol handling

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: samikshya-db

lib/telemetry/DatabricksTelemetryExporter.ts

@@ -0,0 +1,332 @@
+/**
+ * Copyright (c) 2025 Databricks Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import fetch, { Response } from 'node-fetch';
+import IClientContext from '../contracts/IClientContext';
+import { LogLevel } from '../contracts/IDBSQLLogger';
+import { TelemetryMetric, DEFAULT_TELEMETRY_CONFIG } from './types';
+import { CircuitBreakerRegistry } from './CircuitBreaker';
+import ExceptionClassifier from './ExceptionClassifier';
+import { buildUrl } from './urlUtils';
+
+/**
+ * Databricks telemetry log format for export.
+ */
+interface DatabricksTelemetryLog {
+  workspace_id?: string;
+  frontend_log_event_id: string;
+  context: {
+    client_context: {
+      timestamp_millis: number;
+      user_agent: string;
+    };
+  };
+  entry: {
+    sql_driver_log: {
+      session_id?: string;
+      sql_statement_id?: string;
+      system_configuration?: {
+        driver_version?: string;
+        runtime_name?: string;
+        runtime_version?: string;
+        runtime_vendor?: string;
+        os_name?: string;
+        os_version?: string;
+        os_arch?: string;
+        driver_name?: string;
+        client_app_name?: string;
+      };
+      driver_connection_params?: any;
+      operation_latency_ms?: number;
+      sql_operation?: {
+        execution_result?: string;
+        chunk_details?: {
+          total_chunks_present?: number;
+          total_chunks_iterated?: number;
+          initial_chunk_latency_millis?: number;
+          slowest_chunk_latency_millis?: number;
+          sum_chunks_download_time_millis?: number;
+        };
+      };
+      error_info?: {
+        error_name: string;
+        stack_trace: string;
+      };
+    };
+  };
+}
+
+/**
+ * Payload format for Databricks telemetry export.
+ */
+interface DatabricksTelemetryPayload {
+  frontend_logs: DatabricksTelemetryLog[];
+}
+
+/**
+ * Exports telemetry metrics to Databricks telemetry service.
+ *
+ * Endpoints:
+ * - Authenticated: /api/2.0/sql/telemetry-ext
+ * - Unauthenticated: /api/2.0/sql/telemetry-unauth
+ *
+ * Features:
+ * - Circuit breaker integration for endpoint protection
+ * - Retry logic with exponential backoff for retryable errors
+ * - Terminal error detection (no retry on 400, 401, 403, 404)
+ * - CRITICAL: export() method NEVER throws - all exceptions swallowed
+ * - CRITICAL: All logging at LogLevel.debug ONLY
+ */
+export default class DatabricksTelemetryExporter {
+  private circuitBreaker;
+
+  private readonly userAgent: string;
+
+  private fetchFn: typeof fetch;
+
+  constructor(
+    private context: IClientContext,
+    private host: string,
+    private circuitBreakerRegistry: CircuitBreakerRegistry,
+    fetchFunction?: typeof fetch
+  ) {
+    this.circuitBreaker = circuitBreakerRegistry.getCircuitBreaker(host);
+    this.fetchFn = fetchFunction || fetch;
+
+    // Get driver version for user agent
+    this.userAgent = `databricks-sql-nodejs/${this.getDriverVersion()}`;
+  }
+
+  /**
+   * Export metrics to Databricks service. Never throws.
+   *
+   * @param metrics - Array of telemetry metrics to export
+   */
+  async export(metrics: TelemetryMetric[]): Promise<void> {
+    if (!metrics || metrics.length === 0) {
+      return;
+    }
+
+    const logger = this.context.getLogger();
+
+    try {
+      await this.circuitBreaker.execute(async () => {
+        await this.exportWithRetry(metrics);
+      });
+    } catch (error: any) {
+      // CRITICAL: All exceptions swallowed and logged at debug level ONLY
+      if (error.message === 'Circuit breaker OPEN') {
+        logger.log(LogLevel.debug, 'Circuit breaker OPEN - dropping telemetry');
+      } else {
+        logger.log(LogLevel.debug, `Telemetry export error: ${error.message}`);
+      }
+    }
+  }
+
+  /**
+   * Export metrics with retry logic for retryable errors.
+   * Implements exponential backoff with jitter.
+   */
+  private async exportWithRetry(metrics: TelemetryMetric[]): Promise<void> {
+    const config = this.context.getConfig();
+    const logger = this.context.getLogger();
+    const maxRetries = config.telemetryMaxRetries ?? DEFAULT_TELEMETRY_CONFIG.maxRetries;
+
+    let lastError: Error | null = null;
+
+    /* eslint-disable no-await-in-loop */
+    for (let attempt = 0; attempt <= maxRetries; attempt += 1) {
+      try {
+        await this.exportInternal(metrics);
+        return; // Success
+      } catch (error: any) {
+        lastError = error;
+
+        // Check if error is terminal (don't retry)
+        if (ExceptionClassifier.isTerminal(error)) {
+          logger.log(LogLevel.debug, `Terminal error - no retry: ${error.message}`);
+          throw error; // Terminal error, propagate to circuit breaker
+        }
+
+        // Check if error is retryable
+        if (!ExceptionClassifier.isRetryable(error)) {
+          logger.log(LogLevel.debug, `Non-retryable error: ${error.message}`);
+          throw error; // Not retryable, propagate to circuit breaker
+        }
+
+        // Last attempt reached
+        if (attempt >= maxRetries) {
+          logger.log(LogLevel.debug, `Max retries reached (${maxRetries}): ${error.message}`);
+          throw error; // Max retries exhausted, propagate to circuit breaker
+        }
+
+        // Calculate backoff with exponential + jitter (100ms - 1000ms)
+        const baseDelay = Math.min(100 * 2**attempt, 1000);
+        const jitter = Math.random() * 100;
+        const delay = baseDelay + jitter;
+
+        logger.log(
+          LogLevel.debug,
+          `Retrying telemetry export (attempt ${attempt + 1}/${maxRetries}) after ${Math.round(delay)}ms`
+        );
+
+        await this.sleep(delay);
+      }
+    }
+    /* eslint-enable no-await-in-loop */
+
+    // Should not reach here, but just in case
+    if (lastError) {
+      throw lastError;
+    }
+  }
+
+  /**
+   * Internal export implementation that makes the HTTP call.
+   */
+  private async exportInternal(metrics: TelemetryMetric[]): Promise<void> {
+    const config = this.context.getConfig();
+    const logger = this.context.getLogger();
+
+    // Determine endpoint based on authentication mode
+    const authenticatedExport =
+      config.telemetryAuthenticatedExport ?? DEFAULT_TELEMETRY_CONFIG.authenticatedExport;
+    const endpoint = authenticatedExport
+      ? buildUrl(this.host, '/telemetry-ext')
+      : buildUrl(this.host, '/telemetry-unauth');
+
+    // Format payload
+    const payload: DatabricksTelemetryPayload = {
+      frontend_logs: metrics.map((m) => this.toTelemetryLog(m)),
+    };
+
+    logger.log(
+      LogLevel.debug,
+      `Exporting ${metrics.length} telemetry metrics to ${authenticatedExport ? 'authenticated' : 'unauthenticated'} endpoint`
+    );
+
+    // Get authentication headers if using authenticated endpoint
+    const authHeaders = authenticatedExport ? await this.context.getAuthHeaders() : {};
+
+    // Make HTTP POST request with authentication
+    const response: Response = await this.fetchFn(endpoint, {
+      method: 'POST',
+      headers: {
+        ...authHeaders,
+        'Content-Type': 'application/json',
+        'User-Agent': this.userAgent,
+      },
+      body: JSON.stringify(payload),
+    });
+
+    if (!response.ok) {
+      const error: any = new Error(`Telemetry export failed: ${response.status} ${response.statusText}`);
+      error.statusCode = response.status;
+      throw error;
+    }
+
+    logger.log(LogLevel.debug, `Successfully exported ${metrics.length} telemetry metrics`);
+  }
+
+  /**
+   * Convert TelemetryMetric to Databricks telemetry log format.
+   */
+  private toTelemetryLog(metric: TelemetryMetric): DatabricksTelemetryLog {
+    const log: DatabricksTelemetryLog = {
+      // workspace_id: metric.workspaceId, // TODO: Determine if this should be numeric or omitted
+      frontend_log_event_id: this.generateUUID(),
+      context: {
+        client_context: {
+          timestamp_millis: metric.timestamp,
+          user_agent: this.userAgent,
+        },
+      },
+      entry: {
+        sql_driver_log: {
+          session_id: metric.sessionId,
+          sql_statement_id: metric.statementId,
+        },
+      },
+    };
+
+    // Add metric-specific fields based on proto definition
+    if (metric.metricType === 'connection' && metric.driverConfig) {
+      // Map driverConfig to system_configuration (snake_case as per proto)
+      log.entry.sql_driver_log.system_configuration = {
+        driver_version: metric.driverConfig.driverVersion,
+        driver_name: metric.driverConfig.driverName,
+        runtime_name: 'Node.js',
+        runtime_version: metric.driverConfig.nodeVersion,
+        os_name: metric.driverConfig.platform,
+        os_version: metric.driverConfig.osVersion,
+      };
+    } else if (metric.metricType === 'statement') {
+      log.entry.sql_driver_log.operation_latency_ms = metric.latencyMs;
+
+      if (metric.resultFormat || metric.chunkCount) {
+        log.entry.sql_driver_log.sql_operation = {
+          execution_result: metric.resultFormat,
+        };
+
+        if (metric.chunkCount && metric.chunkCount > 0) {
+          log.entry.sql_driver_log.sql_operation.chunk_details = {
+            total_chunks_present: metric.chunkCount,
+            total_chunks_iterated: metric.chunkCount,
+          };
+        }
+      }
+    } else if (metric.metricType === 'error') {
+      log.entry.sql_driver_log.error_info = {
+        error_name: metric.errorName || 'UnknownError',
+        stack_trace: metric.errorMessage || '',
+      };
+    }
+
+    return log;
+  }
+
+  /**
+   * Generate a UUID v4.
+   */
+  private generateUUID(): string {
+    return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, (c) => {
+      const r = (Math.random() * 16) | 0;
+      const v = c === 'x' ? r : (r & 0x3) | 0x8;
+      return v.toString(16);
+    });
+  }
+
+  /**
+   * Get driver version from package.json.
+   */
+  private getDriverVersion(): string {
+    try {
+      // In production, this would read from package.json
+      return '1.0.0';
+    } catch {
+      return 'unknown';
+    }
+  }
+
+  /**
+   * Sleep for the specified number of milliseconds.
+   */
+  private sleep(ms: number): Promise<void> {
+    return new Promise((resolve) => {
+      setTimeout(resolve, ms);
+    });
+  }
+}