Added logging support for OTel

- enabled info logging for OTel, and provides an environment variable
  which allows us to enable debug logging
- this allows us to see messages from OTel that we may
  currently be missing

src/instrumentation.ts

@@ -1,5 +1,10 @@
 import { CloudPropagator } from '@google-cloud/opentelemetry-cloud-trace-propagator';
-import { trace } from '@opentelemetry/api';
+import {
+    DiagConsoleLogger,
+    DiagLogLevel,
+    diag,
+    trace,
+} from '@opentelemetry/api';
 import { getNodeAutoInstrumentations } from '@opentelemetry/auto-instrumentations-node';
 import { NodeSDK } from '@opentelemetry/sdk-node';
 import {
@@ -20,6 +25,14 @@ const sdk = new NodeSDK({
 const provider = new NodeTracerProvider();
 let propagator: CloudPropagator | undefined;
 
+if (process.env.NODE_ENV === 'production') {
+    if (process.env.OTEL_DEBUG_LOGGING) {
+        diag.setLogger(new DiagConsoleLogger(), DiagLogLevel.DEBUG);
+    } else {
+        diag.setLogger(new DiagConsoleLogger(), DiagLogLevel.INFO);
+    }
+}
+
 if (process.env.K_SERVICE) {
     const { TraceExporter } = await import(
         '@google-cloud/opentelemetry-cloud-trace-exporter'