feat(instrumentation-ioredis): add response hook for custom attributes

plugins/node/opentelemetry-instrumentation-ioredis/README.md

@@ -50,6 +50,7 @@ IORedis instrumentation has few options available to choose from. You can set th
 | Options | Type | Description |
 | ------- | ---- | ----------- |
 | `dbStatementSerializer` | `DbStatementSerializer` | IORedis instrumentation will serialize db.statement using the specified function. |
+| `responseHook` | `RedisResponseCustomAttributeFunction` | Function for adding custom attributes on db response |
 
 #### Custom db.statement Serializer
 The instrumentation serializes the whole command into a Span attribute called `db.statement`. The standard serialization format is `{cmdName} {cmdArgs.join(',')}`.

plugins/node/opentelemetry-instrumentation-ioredis/src/types.ts

@@ -16,6 +16,7 @@
 
 import type * as ioredisTypes from 'ioredis';
 import { InstrumentationConfig } from '@opentelemetry/instrumentation';
+import { Span } from '@opentelemetry/api';
 
 // eslint-disable-next-line @typescript-eslint/interface-name-prefix
 export interface IORedisCommand {
@@ -39,11 +40,32 @@ export type DbStatementSerializer = (
   cmdArgs: IORedisCommand['args']
 ) => string;
 
+/**
+ * Function that can be used to add custom attributes to span on response from redis server
+ * @param span - The span created for the redis command, on which attributes can be set
+ * @param cmdName - The name of the command (eg. set, get, mset)
+ * @param cmdArgs - Array of arguments passed to the command
+ * @param response - The response object which is returned to the user who called this command.
+ *  Can be used to set custom attributes on the span
+ */
+export interface RedisResponseCustomAttributeFunction {
+  (
+    span: Span,
+    cmdName: IORedisCommand['name'],
+    cmdArgs: IORedisCommand['args'],
+    /* eslint-disable @typescript-eslint/no-explicit-any */
+    response: any
+  ): void;
+}
+
 /**
  * Options available for the IORedis Instrumentation (see [documentation](https://github.com/open-telemetry/opentelemetry-js/tree/main/packages/opentelemetry-instrumentation-ioredis#ioredis-instrumentation-options))
  */
 // eslint-disable-next-line @typescript-eslint/interface-name-prefix
 export interface IORedisInstrumentationConfig extends InstrumentationConfig {
   /** Custom serializer function for the db.statement tag */
   dbStatementSerializer?: DbStatementSerializer;
+
+  /** Function for adding custom attributes on db response */
+  responseHook?: RedisResponseCustomAttributeFunction;
 }

plugins/node/opentelemetry-instrumentation-ioredis/src/utils.ts

@@ -33,6 +33,7 @@ import {
   DatabaseAttribute,
   GeneralAttribute,
 } from '@opentelemetry/semantic-conventions';
+import { safeExecuteInTheMiddle } from '@opentelemetry/instrumentation';
 
 const endSpan = (span: Span, err: NodeJS.ErrnoException | null | undefined) => {
   if (err) {
@@ -121,6 +122,12 @@ export const traceSendCommand = (
       const origResolve = cmd.resolve;
       /* eslint-disable @typescript-eslint/no-explicit-any */
       cmd.resolve = function (result: any) {
+        safeExecuteInTheMiddle(
+          () => config?.responseHook?.(span, cmd.name, cmd.args, result),
+          () => {},
+          true
+        );
+
         endSpan(span, null);
         origResolve(result);
       };

plugins/node/opentelemetry-instrumentation-ioredis/test/ioredis.test.ts

@@ -21,6 +21,7 @@ import {
   Status,
   getSpan,
   setSpan,
+  Span,
 } from '@opentelemetry/api';
 import { NodeTracerProvider } from '@opentelemetry/node';
 import { AsyncHooksContextManager } from '@opentelemetry/context-async-hooks';
@@ -711,5 +712,67 @@ describe('ioredis', () => {
         });
       });
     });
+
+    describe('Instrumenting with a custom responseHook', () => {
+      it('should call responseHook when set in config', async () => {
+        instrumentation.disable();
+        const config: IORedisInstrumentationConfig = {
+          responseHook: (
+            span: Span,
+            cmdName: string,
+            _cmdArgs: Array<string | Buffer | number>,
+            response: any
+          ) => {
+            assert.strictEqual(cmdName, 'incr');
+            // the command is 'incr' on a key which does not exist, thus it increase 0 by 1 and respond 1
+            assert.strictEqual(response, 1);
+            span.setAttribute(
+              'attribute key from hook',
+              'custom value from hook'
+            );
+          },
+        };
+        instrumentation = new IORedisInstrumentation(config);
+        instrumentation.setTracerProvider(provider);
+        require('ioredis');
+
+        const span = provider.getTracer('ioredis-test').startSpan('test span');
+        await context.with(setSpan(context.active(), span), async () => {
+          await client.incr('new-key');
+          const endedSpans = memoryExporter.getFinishedSpans();
+          assert.strictEqual(endedSpans.length, 1);
+          assert.strictEqual(
+            endedSpans[0].attributes['attribute key from hook'],
+            'custom value from hook'
+          );
+        });
+      });
+
+      it('should ignore responseHook which throws exception', async () => {
+        instrumentation.disable();
+        const config: IORedisInstrumentationConfig = {
+          responseHook: (
+            _span: Span,
+            _cmdName: string,
+            _cmdArgs: Array<string | Buffer | number>,
+            _response: any
+          ) => {
+            throw Error('error thrown in responseHook');
+          },
+        };
+        instrumentation = new IORedisInstrumentation(config);
+        instrumentation.setTracerProvider(provider);
+        require('ioredis');
+
+        const span = provider.getTracer('ioredis-test').startSpan('test span');
+        await context.with(setSpan(context.active(), span), async () => {
+          await client.incr('some-key');
+          const endedSpans = memoryExporter.getFinishedSpans();
+
+          // hook throw exception, but span should not be affected
+          assert.strictEqual(endedSpans.length, 1);
+        });
+      });
+    });
   });
 });