From 9b4f2a516d91d2d2df0a6717ad93f378c298d6ac Mon Sep 17 00:00:00 2001
From: Chengzhong Wu <legendecas@gmail.com>
Date: Wed, 22 Feb 2023 21:26:04 +0800
Subject: [PATCH] feat(sdk-node): install diag log with OTEL_LOG_LEVEL (#3627)

---
 experimental/CHANGELOG.md                     |  1 +
 .../packages/opentelemetry-sdk-node/README.md | 16 +++++++++++-
 .../opentelemetry-sdk-node/src/sdk.ts         | 16 ++++++++++--
 .../opentelemetry-sdk-node/test/sdk.test.ts   | 25 +++++++++++++++++++
 4 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/experimental/CHANGELOG.md b/experimental/CHANGELOG.md
index 5f14e88c50..c8bddd915c 100644
--- a/experimental/CHANGELOG.md
+++ b/experimental/CHANGELOG.md
@@ -9,6 +9,7 @@ All notable changes to experimental packages in this project will be documented
 ### :rocket: (Enhancement)
 
 * feat: add HTTP_ROUTE attribute to http incoming metrics if present [#3581](https://github.com/open-telemetry/opentelemetry-js/pull/3581) @hermogenes
+* feat(sdk-node): install diag logger with OTEL_LOG_LEVEL [#3627](https://github.com/open-telemetry/opentelemetry-js/pull/3627) @legendecas
 
 ### :bug: (Bug Fix)
 
diff --git a/experimental/packages/opentelemetry-sdk-node/README.md b/experimental/packages/opentelemetry-sdk-node/README.md
index 0bac781143..693f91ae74 100644
--- a/experimental/packages/opentelemetry-sdk-node/README.md
+++ b/experimental/packages/opentelemetry-sdk-node/README.md
@@ -143,7 +143,21 @@ Configure the [service name](https://github.com/open-telemetry/opentelemetry-spe
 
 Disable the SDK by setting the `OTEL_SDK_DISABLED` environment variable to `true`.
 
-## Configure Trace Exporter from  Environment
+## Configure log level from the environment
+
+Set the log level by setting the `OTEL_LOG_LEVEL` environment variable to enums:
+
+- `NONE`,
+- `ERROR`,
+- `WARN`,
+- `INFO`,
+- `DEBUG`,
+- `VERBOSE`,
+- `ALL`.
+
+The default level is `INFO`.
+
+## Configure Trace Exporter from environment
 
 This is an alternative to programmatically configuring an exporter or span processor. This package will auto setup the default `otlp` exporter with `http/protobuf` protocol if `traceExporter` or `spanProcessor` hasn't been passed into the `NodeSDK` constructor.
 
diff --git a/experimental/packages/opentelemetry-sdk-node/src/sdk.ts b/experimental/packages/opentelemetry-sdk-node/src/sdk.ts
index fa14043cd3..faae12dc7d 100644
--- a/experimental/packages/opentelemetry-sdk-node/src/sdk.ts
+++ b/experimental/packages/opentelemetry-sdk-node/src/sdk.ts
@@ -14,7 +14,13 @@
  * limitations under the License.
  */
 
-import { ContextManager, TextMapPropagator, metrics } from '@opentelemetry/api';
+import {
+  ContextManager,
+  TextMapPropagator,
+  metrics,
+  diag,
+  DiagConsoleLogger,
+} from '@opentelemetry/api';
 import {
   InstrumentationOption,
   registerInstrumentations,
@@ -80,11 +86,17 @@ export class NodeSDK {
    * Create a new NodeJS SDK instance
    */
   public constructor(configuration: Partial<NodeSDKConfiguration> = {}) {
-    if (getEnv().OTEL_SDK_DISABLED) {
+    const env = getEnv();
+    if (env.OTEL_SDK_DISABLED) {
       this._disabled = true;
       // Functions with possible side-effects are set
       // to no-op via the _disabled flag
     }
+    if (env.OTEL_LOG_LEVEL) {
+      diag.setLogger(new DiagConsoleLogger(), {
+        logLevel: env.OTEL_LOG_LEVEL,
+      });
+    }
 
     this._resource = configuration.resource ?? new Resource({});
     this._resourceDetectors = configuration.resourceDetectors ?? [
diff --git a/experimental/packages/opentelemetry-sdk-node/test/sdk.test.ts b/experimental/packages/opentelemetry-sdk-node/test/sdk.test.ts
index 60b493435b..fb43901710 100644
--- a/experimental/packages/opentelemetry-sdk-node/test/sdk.test.ts
+++ b/experimental/packages/opentelemetry-sdk-node/test/sdk.test.ts
@@ -22,6 +22,7 @@ import {
   diag,
   DiagLogLevel,
   metrics,
+  DiagConsoleLogger,
 } from '@opentelemetry/api';
 import {
   AsyncHooksContextManager,
@@ -68,6 +69,7 @@ describe('Node SDK', () => {
   let delegate: any;
 
   beforeEach(() => {
+    diag.disable();
     context.disable();
     trace.disable();
     propagation.disable();
@@ -78,6 +80,10 @@ describe('Node SDK', () => {
     delegate = (trace.getTracerProvider() as ProxyTracerProvider).getDelegate();
   });
 
+  afterEach(() => {
+    Sinon.restore();
+  });
+
   describe('Basic Registration', () => {
     it('should not register any unconfigured SDK components', async () => {
       // need to set OTEL_TRACES_EXPORTER to none since default value is otlp
@@ -108,6 +114,25 @@ describe('Node SDK', () => {
       delete env.OTEL_TRACES_EXPORTER;
     });
 
+    it('should register a diag logger with OTEL_LOG_LEVEL', () => {
+      env.OTEL_LOG_LEVEL = 'ERROR';
+
+      const spy = Sinon.spy(diag, 'setLogger');
+      const sdk = new NodeSDK({
+        autoDetectResources: false,
+      });
+
+      sdk.start();
+
+      assert.strictEqual(spy.callCount, 1);
+      assert.ok(spy.args[0][0] instanceof DiagConsoleLogger);
+      assert.deepStrictEqual(spy.args[0][1], {
+        logLevel: DiagLogLevel.ERROR,
+      });
+
+      delete env.OTEL_LOG_LEVEL;
+    });
+
     it('should register a tracer provider if an exporter is provided', async () => {
       const sdk = new NodeSDK({
         traceExporter: new ConsoleSpanExporter(),