Remove MetaRewritePolicy 'add' mode.

Author: lukeelmers

src/core/server/logging/README.mdx

@@ -317,8 +317,7 @@ The `meta` rewrite policy can read and modify any data contained in the
 
 Meta policies must specify one of three modes, which indicate which action
 to perform on the configured properties:
-- `add` creates a new property at the provided `path`, skipping properties which already exist.
-- `update` updates an existing property at the provided `path` without creating new properties.
+- `update` updates an existing property at the provided `path`.
 - `remove` removes an existing property at the provided `path`.
 
 The `properties` are listed as a `path` and `value` pair, where `path` is
@@ -348,25 +347,23 @@ reference. Each rewrite appender is applied sequentially (one after the other).
 ```yaml
 logging:
   appenders:
-    remove-stuff:
+    remove-request-headers:
       type: rewrite
-      appenders: [add-stuff] # redirect to the next rewrite appender
+      appenders: [censor-response-headers] # redirect to the next rewrite appender
       policy:
         type: meta
         mode: remove
         properties:
-          - path: "http.request.headers.authorization"
-          - path: "http.request.headers.cookie"
-          - path: "http.request.headers.set-cookie"
-    add-stuff:
+          - path: "http.request.headers" # remove all request headers
+    censor-response-headers:
       type: rewrite
       appenders: [console] # output to console
       policy:
         type: meta
-        mode: add
+        mode: update
         properties:
-          - path: "hello"
-            value: "world" # creates { hello: 'world' } at the LogMeta root
+          - path: "http.response.headers.set-cookie"
+            value: "[REDACTED]"
 ```
 
 #### Complete Example

src/core/server/logging/appenders/rewrite/policies/meta/meta_policy.test.ts

@@ -24,80 +24,6 @@ describe('MetaRewritePolicy', () => {
     meta,
   });
 
-  describe('mode: add', () => {
-    it('adds new properties to LogMeta', () => {
-      const policy = createPolicy('add', [{ path: 'foo', value: 'bar' }]);
-      const log = createLogRecord();
-      expect(policy.rewrite(log).meta).toMatchInlineSnapshot(`
-        Object {
-          "foo": "bar",
-        }
-      `);
-    });
-
-    it('adds nested properties to LogMeta', () => {
-      const policy = createPolicy('add', [
-        { path: 'a.b', value: 'foo' },
-        { path: 'a.c[1]', value: 'bar' },
-      ]);
-      const log = createLogRecord();
-      expect(policy.rewrite(log).meta).toMatchInlineSnapshot(`
-        Object {
-          "a": Object {
-            "b": "foo",
-            "c": Array [
-              undefined,
-              "bar",
-            ],
-          },
-        }
-      `);
-    });
-
-    it('handles string, number, boolean, null', () => {
-      const policy = createPolicy('add', [
-        { path: 'boolean', value: false },
-        { path: 'null', value: null },
-        { path: 'number', value: 123 },
-        { path: 'string', value: 'hi' },
-      ]);
-      const log = createLogRecord();
-      expect(policy.rewrite(log).meta).toMatchInlineSnapshot(`
-        Object {
-          "boolean": false,
-          "null": null,
-          "number": 123,
-          "string": "hi",
-        }
-      `);
-    });
-
-    it('does not overwrite properties which already exist', () => {
-      const policy = createPolicy('add', [
-        { path: 'a.b', value: 'foo' },
-        { path: 'a.c', value: 'bar' },
-      ]);
-      const log = createLogRecord({ a: { b: 'existing meta' } });
-      const { meta } = policy.rewrite(log);
-      expect(meta!.a.b).toBe('existing meta');
-      expect(meta!.a.c).toBe('bar');
-    });
-
-    it('does not touch anything outside of LogMeta', () => {
-      const policy = createPolicy('add', [{ path: 'message', value: 'bar' }]);
-      const message = Symbol();
-      expect(policy.rewrite(({ message } as unknown) as LogRecord).message).toBe(message);
-      expect(policy.rewrite(({ message } as unknown) as LogRecord)).toMatchInlineSnapshot(`
-        Object {
-          "message": Symbol(),
-          "meta": Object {
-            "message": "bar",
-          },
-        }
-      `);
-    });
-  });
-
   describe('mode: update', () => {
     it('updates existing properties in LogMeta', () => {
       const log = createLogRecord({ a: 'before' });

src/core/server/logging/appenders/rewrite/policies/meta/meta_policy.ts

@@ -23,14 +23,13 @@ export interface MetaRewritePolicyConfig {
 
   /**
    * The 'mode' specifies what action to perform on the specified properties.
-   *   - 'add' creates a new property at the provided 'path', skipping properties which already exist.
-   *   - 'update' updates an existing property at the provided 'path' without creating new properties.
+   *   - 'update' updates an existing property at the provided 'path'.
    *   - 'remove' removes an existing property at the provided 'path'.
    */
-  mode: 'add' | 'remove' | 'update';
+  mode: 'remove' | 'update';
 
   /**
-   * The properties to add, remove, or update.
+   * The properties to modify.
    *
    * @remarks
    * Each provided 'path' is relative to the record's {@link LogMeta}.
@@ -41,7 +40,7 @@ export interface MetaRewritePolicyConfig {
 
 export const metaRewritePolicyConfigSchema = schema.object({
   type: schema.literal('meta'),
-  mode: schema.oneOf([schema.literal('add'), schema.literal('update'), schema.literal('remove')], {
+  mode: schema.oneOf([schema.literal('update'), schema.literal('remove')], {
     defaultValue: 'update',
   }),
   properties: schema.arrayOf(
@@ -63,8 +62,6 @@ export class MetaRewritePolicy implements RewritePolicy {
 
   rewrite(record: LogRecord): LogRecord {
     switch (this.config.mode) {
-      case 'add':
-        return this.add(record);
       case 'update':
         return this.update(record);
       case 'remove':
@@ -74,16 +71,6 @@ export class MetaRewritePolicy implements RewritePolicy {
     }
   }
 
-  private add(record: LogRecord) {
-    for (const { path, value } of this.config.properties) {
-      if (has(record, `meta.${path}`)) {
-        continue; // don't overwrite properties which already exist
-      }
-      set(record, `meta.${path}`, value);
-    }
-    return record;
-  }
-
   private update(record: LogRecord) {
     for (const { path, value } of this.config.properties) {
       if (!has(record, `meta.${path}`)) {