feat: Omit default headers from req.headers prop

README.md

@@ -57,7 +57,9 @@ Use the following standardised logging fields to benefit from customised seriali
 
 - `req` for HTTP requests.
 
-  The request object is trimmed to a set of essential fields.
+  The request object is trimmed to a set of essential fields.  
+  Certain headers are omitted by default (e.g. `x-envoy-peer-metadata`).  
+  To opt out of this behavior, set the `omitHeaderNames` logger option to an empty list `[]`.
 
 - `res` for HTTP responses.
 

src/index.test.ts

@@ -574,12 +574,25 @@ testLog(
       ...objectWithDefaultOmitHeaderNameKeys,
       ['x-request-id']: 'some-uuid',
     },
+    req: {
+      headers: {
+        ['authorization']: bearerToken,
+        ...objectWithDefaultOmitHeaderNameKeys,
+        ['x-request-id']: 'some-uuid',
+      },
+    },
   },
   {
     headers: {
       ['authorization']: redactedBearer,
       ['x-request-id']: 'some-uuid',
     },
+    req: {
+      headers: {
+        ['authorization']: redactedBearer,
+        ['x-request-id']: 'some-uuid',
+      },
+    },
   },
   'info',
 );
@@ -592,13 +605,27 @@ testLog(
       ...objectWithDefaultOmitHeaderNameKeys,
       ['x-request-id']: 'some-uuid',
     },
+    req: {
+      headers: {
+        ['authorization']: bearerToken,
+        ...objectWithDefaultOmitHeaderNameKeys,
+        ['x-request-id']: 'some-uuid',
+      },
+    },
   },
   {
     headers: {
       ['authorization']: redactedBearer,
       ...objectWithDefaultOmitHeaderNameKeys,
       ['x-request-id']: 'some-uuid',
     },
+    req: {
+      headers: {
+        ['authorization']: redactedBearer,
+        ...objectWithDefaultOmitHeaderNameKeys,
+        ['x-request-id']: 'some-uuid',
+      },
+    },
   },
   'info',
   { omitHeaderNames: [] },

src/index.ts

@@ -4,11 +4,7 @@ import base from './base';
 import { withRedaction } from './destination';
 import { type FormatterOptions, createFormatters } from './formatters';
 import * as redact from './redact';
-import defaultSerializers, {
-  type SerializerOptions,
-  defaultOmitHeaderNames,
-} from './serializers';
-import { createOmitPropertiesSerializer } from './serializers/omitPropertiesSerializer';
+import { type SerializerOptions, createSerializers } from './serializers';
 
 export { pino };
 
@@ -31,14 +27,7 @@ export default (
   }),
 ): Logger => {
   opts.redact = redact.addDefaultRedactPathStrings(opts.redact);
-  const omitHeaderNamesSerializer = createOmitPropertiesSerializer('headers', {
-    omitPropertyNames: opts.omitHeaderNames ?? defaultOmitHeaderNames,
-  });
-  opts.serializers = {
-    ...defaultSerializers,
-    ...omitHeaderNamesSerializer,
-    ...opts.serializers,
-  };
+  opts.serializers = createSerializers(opts);
   const formatters = createFormatters(opts);
   opts.base = {
     ...base,

src/serializers/index.test.ts

@@ -1,4 +1,4 @@
-import serializers from './index';
+import serializers, { type Request, defaultOmitHeaderNames } from './index';
 
 describe('req', () => {
   const remoteAddress = '::ffff:123.45.67.89';
@@ -88,6 +88,23 @@ describe('req', () => {
 
     expect(result).toStrictEqual({ ...expectedRequestBase });
   });
+
+  it('omits defaultOmitHeaderNames by default', () => {
+    const objectWithDefaultOmitHeaderNameKeys = defaultOmitHeaderNames.reduce(
+      (headers, key) => ({ ...headers, [key]: 'header value' }),
+      {},
+    );
+    const request = {
+      ...requestBase,
+      headers: {
+        ...requestBase.headers,
+        ...objectWithDefaultOmitHeaderNameKeys,
+      },
+    } as Partial<Request> as Request;
+    const result = serializers.req(request);
+
+    expect(result).toStrictEqual({ ...expectedRequestBase });
+  });
 });
 
 describe('res', () => {

src/serializers/index.ts

@@ -1,5 +1,9 @@
+import type pino from 'pino';
 import { err, errWithCause } from 'pino-std-serializers';
 
+import { omitProperties } from './omitProperties';
+import { createOmitPropertiesSerializer } from './omitPropertiesSerializer';
+
 export const defaultOmitHeaderNames = [
   'x-envoy-attempt-count',
   'x-envoy-decorator-operation',
@@ -18,7 +22,7 @@ interface Socket {
   remoteAddress?: string;
   remotePort?: string;
 }
-interface Request extends Record<string, unknown> {
+export interface Request extends Record<string, unknown> {
   method: string;
   url: string;
   headers: Record<string, string>;
@@ -40,16 +44,23 @@ const isObject = (value: unknown): boolean => {
   return value != null && (type === 'object' || type === 'function');
 };
 
-const req = (request: Request) =>
-  isObject(request)
-    ? {
-        method: request.method,
-        url: request.url,
-        headers: request.headers,
-        remoteAddress: request?.socket?.remoteAddress,
-        remotePort: request?.socket?.remotePort,
-      }
-    : request;
+export const createReqSerializer = (opts: SerializerOptions) => {
+  const req = (request: Request) =>
+    isObject(request)
+      ? {
+          method: request.method,
+          url: request.url,
+          headers: omitProperties(
+            request.headers,
+            opts.omitHeaderNames ?? defaultOmitHeaderNames,
+          ),
+          remoteAddress: request?.socket?.remoteAddress,
+          remotePort: request?.socket?.remotePort,
+        }
+      : request;
+
+  return req;
+};
 
 const res = (response: Response) =>
   isObject(response)
@@ -59,9 +70,25 @@ const res = (response: Response) =>
       }
     : response;
 
-export default {
+export const createSerializers = (
+  opts: SerializerOptions & Pick<pino.LoggerOptions, 'serializers'>,
+) => {
+  const omitHeaderNamesSerializer = createOmitPropertiesSerializer('headers', {
+    omitPropertyNames: opts.omitHeaderNames ?? defaultOmitHeaderNames,
+  });
+  return {
+    ...defaultSerializers,
+    req: createReqSerializer(opts),
+    ...omitHeaderNamesSerializer,
+    ...opts.serializers,
+  };
+};
+
+const defaultSerializers = {
   err,
   errWithCause,
   res,
-  req,
+  req: createReqSerializer({}),
 };
+
+export default defaultSerializers;