[APM Tracing config] Allow per-service overrides (#166184)

Co-authored-by: Kibana Machine <42973632+kibanamachine@users.noreply.github.com>

packages/kbn-apm-config-loader/src/apm_config.ts

@@ -6,14 +6,22 @@
  * Side Public License, v 1.
  */
 
-import { schema } from '@kbn/config-schema';
+import { schema, TypeOf } from '@kbn/config-schema';
 
-export const apmConfigSchema = schema.object(
+export type ApmConfigSchema = TypeOf<typeof apmConfigSchema>;
+
+const apmReusableConfigSchema = schema.object(
   {
     active: schema.maybe(schema.boolean()),
     serverUrl: schema.maybe(schema.uri()),
     secretToken: schema.maybe(schema.string()),
-    globalLabels: schema.object({}, { unknowns: 'allow' }),
+    apiKey: schema.maybe(schema.string()),
+    environment: schema.maybe(schema.string()),
+    globalLabels: schema.maybe(schema.object({}, { unknowns: 'allow' })),
   },
   { unknowns: 'allow' }
 );
+
+export const apmConfigSchema = apmReusableConfigSchema.extends({
+  servicesOverrides: schema.maybe(schema.recordOf(schema.string(), apmReusableConfigSchema)),
+});

packages/kbn-apm-config-loader/src/config.test.ts

@@ -359,5 +359,50 @@ describe('ApmConfiguration', () => {
         })
       );
     });
+
+    it('allows overriding some services settings', () => {
+      const kibanaConfig = {
+        elastic: {
+          apm: {
+            active: true,
+            serverUrl: 'http://an.internal.apm.server:port/',
+            transactionSampleRate: 0.1,
+            servicesOverrides: {
+              externalServiceName: {
+                active: false,
+                serverUrl: 'http://a.public.apm.server:port/',
+                disableSend: true, // just adding an extra field to prove merging works
+              },
+            },
+          },
+        },
+      };
+
+      const internalService = new ApmConfiguration(mockedRootDir, kibanaConfig, true).getConfig(
+        'internalServiceName'
+      );
+      expect(internalService).toEqual(
+        expect.objectContaining({
+          active: true,
+          serverUrl: 'http://an.internal.apm.server:port/',
+          transactionSampleRate: 0.1,
+          serviceName: 'internalServiceName',
+        })
+      );
+      expect(internalService).not.toHaveProperty('disableSend');
+      expect(internalService).not.toHaveProperty('servicesOverrides'); // We don't want to leak this to the client's config
+
+      expect(
+        new ApmConfiguration(mockedRootDir, kibanaConfig, true).getConfig('externalServiceName')
+      ).toEqual(
+        expect.objectContaining({
+          active: false,
+          serverUrl: 'http://a.public.apm.server:port/',
+          transactionSampleRate: 0.1,
+          disableSend: true,
+          serviceName: 'externalServiceName',
+        })
+      );
+    });
   });
 });

packages/kbn-apm-config-loader/src/config.ts

@@ -14,6 +14,7 @@ import { getDataPath } from '@kbn/utils';
 import { readFileSync } from 'fs';
 import type { AgentConfigOptions } from 'elastic-apm-node';
 import type { AgentConfigOptions as RUMAgentConfigOptions } from '@elastic/apm-rum';
+import type { ApmConfigSchema } from './apm_config';
 
 // https://www.elastic.co/guide/en/apm/agent/nodejs/current/configuration.html
 const DEFAULT_CONFIG: AgentConfigOptions = {
@@ -49,6 +50,18 @@ const CENTRALIZED_SERVICE_DIST_CONFIG: AgentConfigOptions = {
   transactionSampleRate: 0.1,
 };
 
+interface KibanaRawConfig {
+  elastic?: {
+    apm?: ApmConfigSchema;
+  };
+  path?: {
+    data?: string;
+  };
+  server?: {
+    uuid?: string;
+  };
+}
+
 export class ApmConfiguration {
   private baseConfig?: AgentConfigOptions;
   private kibanaVersion: string;
@@ -56,7 +69,7 @@ export class ApmConfiguration {
 
   constructor(
     private readonly rootDir: string,
-    private readonly rawKibanaConfig: Record<string, any>,
+    private readonly rawKibanaConfig: KibanaRawConfig,
     private readonly isDistributable: boolean
   ) {
     // eslint-disable-next-line @typescript-eslint/no-var-requires
@@ -66,10 +79,19 @@ export class ApmConfiguration {
   }
 
   public getConfig(serviceName: string): AgentConfigOptions {
-    return {
+    const { servicesOverrides = {} } = this.getConfigFromKibanaConfig();
+
+    let baseConfig = {
       ...this.getBaseConfig(),
       serviceName,
     };
+
+    const serviceOverride = servicesOverrides[serviceName];
+    if (serviceOverride) {
+      baseConfig = merge({}, baseConfig, serviceOverride);
+    }
+
+    return baseConfig;
   }
 
   private getBaseConfig() {
@@ -166,7 +188,7 @@ export class ApmConfiguration {
    * Get the elastic.apm configuration from the --config file, supersedes the
    * default config.
    */
-  private getConfigFromKibanaConfig(): AgentConfigOptions {
+  private getConfigFromKibanaConfig(): ApmConfigSchema {
     return this.rawKibanaConfig?.elastic?.apm ?? {};
   }
 
@@ -266,7 +288,7 @@ export class ApmConfiguration {
    * Reads APM configuration from different sources and merges them together.
    */
   private getConfigFromAllSources(): AgentConfigOptions {
-    const configFromKibanaConfig = this.getConfigFromKibanaConfig();
+    const { servicesOverrides, ...configFromKibanaConfig } = this.getConfigFromKibanaConfig();
     const configFromEnv = this.getConfigFromEnv(configFromKibanaConfig);
     const config = merge({}, configFromKibanaConfig, configFromEnv);