BREAKING CHANGE(core): Refactor to v3: introduce modular core/domain architecture, plugin system, observability and strict TypeScript configuration; remove legacy classes

ts/core/plugins/built-in/metrics-plugin.ts

@@ -0,0 +1,141 @@
+/**
+ * Metrics Plugin
+ *
+ * Automatically collects metrics for requests and responses
+ */
+
+import { defaultMetricsCollector } from '../../observability/metrics.js';
+import type { Plugin, PluginContext, PluginResponse, MetricsPluginConfig } from '../types.js';
+
+/**
+ * Default configuration
+ */
+const DEFAULT_CONFIG: Required<MetricsPluginConfig> = {
+  enabled: true,
+  prefix: 'elasticsearch',
+  recordDuration: true,
+  recordSize: true,
+  recordResponseSize: true,
+};
+
+/**
+ * Create metrics plugin
+ */
+export function createMetricsPlugin(config: MetricsPluginConfig = {}): Plugin {
+  const pluginConfig = { ...DEFAULT_CONFIG, ...config };
+  const metrics = defaultMetricsCollector;
+
+  return {
+    name: 'metrics',
+    version: '1.0.0',
+    priority: 20, // Execute early, after logging
+
+    beforeRequest: (context: PluginContext) => {
+      if (!pluginConfig.enabled) {
+        return context;
+      }
+
+      // Record request counter
+      metrics.recordCounter(`${pluginConfig.prefix}.requests`, 1, {
+        method: context.request.method,
+        path: extractIndexFromPath(context.request.path),
+      });
+
+      // Record request size if enabled
+      if (pluginConfig.recordSize && context.request.body) {
+        const size = Buffer.byteLength(JSON.stringify(context.request.body), 'utf8');
+        metrics.recordHistogram(`${pluginConfig.prefix}.request.size`, size, {
+          method: context.request.method,
+        });
+      }
+
+      return context;
+    },
+
+    afterResponse: <T>(context: PluginContext, response: PluginResponse<T>) => {
+      if (!pluginConfig.enabled) {
+        return response;
+      }
+
+      const duration = Date.now() - context.request.startTime;
+
+      // Record request duration if enabled
+      if (pluginConfig.recordDuration) {
+        metrics.recordHistogram(`${pluginConfig.prefix}.request.duration`, duration, {
+          method: context.request.method,
+          path: extractIndexFromPath(context.request.path),
+          status: response.statusCode.toString(),
+        });
+      }
+
+      // Record response size if enabled
+      if (pluginConfig.recordResponseSize && response.body) {
+        const size = Buffer.byteLength(JSON.stringify(response.body), 'utf8');
+        metrics.recordHistogram(`${pluginConfig.prefix}.response.size`, size, {
+          method: context.request.method,
+          status: response.statusCode.toString(),
+        });
+      }
+
+      // Record success/failure
+      const success = response.statusCode >= 200 && response.statusCode < 300;
+      metrics.recordCounter(
+        `${pluginConfig.prefix}.requests.${success ? 'success' : 'failure'}`,
+        1,
+        {
+          method: context.request.method,
+          status: response.statusCode.toString(),
+        }
+      );
+
+      return response;
+    },
+
+    onError: (context) => {
+      if (!pluginConfig.enabled) {
+        return null;
+      }
+
+      const duration = Date.now() - context.request.startTime;
+
+      // Record error
+      metrics.recordCounter(`${pluginConfig.prefix}.errors`, 1, {
+        method: context.request.method,
+        path: extractIndexFromPath(context.request.path),
+        error: context.error.name,
+      });
+
+      // Record error duration
+      if (pluginConfig.recordDuration) {
+        metrics.recordHistogram(`${pluginConfig.prefix}.error.duration`, duration, {
+          method: context.request.method,
+          error: context.error.name,
+        });
+      }
+
+      // Don't handle error
+      return null;
+    },
+  };
+}
+
+/**
+ * Extract index name from path
+ */
+function extractIndexFromPath(path: string): string {
+  // Remove leading slash
+  const cleanPath = path.startsWith('/') ? path.slice(1) : path;
+
+  // Split by slash and get first segment
+  const segments = cleanPath.split('/');
+
+  // Common patterns:
+  // /{index}/_search
+  // /{index}/_doc/{id}
+  // /_cat/indices
+  if (segments[0].startsWith('_')) {
+    return segments[0]; // API endpoint like _cat, _search
+  }
+
+  return segments[0] || 'unknown';
+}