add metrics.ts and use in base-service

packages/core-utils/src/base-service.ts

 /* Imports: Internal */
 import { Logger } from './common/logger'
+import { Metrics } from './common/metrics'
 
 type OptionSettings<TOptions> = {
   [P in keyof TOptions]?: {
@@ -16,6 +17,7 @@ export class BaseService<T> {
   protected name: string
   protected options: T
   protected logger: Logger
+  protected metrics: Metrics
   protected initialized: boolean = false
   protected running: boolean = false
 
@@ -24,6 +26,7 @@ export class BaseService<T> {
     this.name = name
     this.options = mergeDefaultOptions(options, optionSettings)
     this.logger = new Logger({ name })
+    this.metrics = new Metrics({ prefix: name })
   }
 
   /**

packages/core-utils/src/common/metrics.ts

+import prometheus, {
+  collectDefaultMetrics,
+  DefaultMetricsCollectorConfiguration,
+  Registry,
+} from 'prom-client'
+
+export interface MetricsOptions {
+  prefix: string
+  labels?: Object
+}
+
+export class Metrics {
+  options: MetricsOptions
+  client: typeof prometheus
+  registry: Registry
+
+  constructor(options: MetricsOptions) {
+    this.options = options
+
+    const metricsOptions: DefaultMetricsCollectorConfiguration = {
+      prefix: options.prefix,
+      labels: options.labels,
+    }
+
+    this.client = prometheus
+    this.registry = prometheus.register
+
+    // Collect default metrics (event loop lag, memory, file descriptors etc.)
+    collectDefaultMetrics(metricsOptions)
+  }
+}