feat: allow defining custom build log transport for techdocs

should enable way to overcome #24583 memory leak, maybe.

Signed-off-by: Heikki Hellgren <heikki.hellgren@op.fi>

.changeset/cuddly-eggs-sin.md

@@ -0,0 +1,6 @@
+---
+'@backstage/plugin-techdocs-backend': patch
+'@backstage/plugin-techdocs-node': patch
+---
+
+Allow defining custom build log transport for techdocs builder

plugins/techdocs-backend/src/plugin.ts

@@ -38,6 +38,7 @@ import {
 } from '@backstage/plugin-techdocs-node';
 import Docker from 'dockerode';
 import { createRouter } from '@backstage/plugin-techdocs-backend';
+import * as winston from 'winston';
 
 /**
  * The TechDocs plugin is responsible for serving and building documentation for any entity.
@@ -47,6 +48,7 @@ export const techdocsPlugin = createBackendPlugin({
   pluginId: 'techdocs',
   register(env) {
     let docsBuildStrategy: DocsBuildStrategy | undefined;
+    let buildLogTransport: winston.transport | undefined;
     env.registerExtensionPoint(techdocsBuildsExtensionPoint, {
       setBuildStrategy(buildStrategy: DocsBuildStrategy) {
         if (docsBuildStrategy) {
@@ -54,6 +56,12 @@ export const techdocsPlugin = createBackendPlugin({
         }
         docsBuildStrategy = buildStrategy;
       },
+      setBuildLogTransport(transport: winston.transport) {
+        if (buildLogTransport) {
+          throw new Error('BuildLogTransport may only be set once');
+        }
+        buildLogTransport = transport;
+      },
     });
 
     let customTechdocsGenerator: TechdocsGenerator | undefined;
@@ -138,6 +146,7 @@ export const techdocsPlugin = createBackendPlugin({
             logger: winstonLogger,
             cache: cacheManager,
             docsBuildStrategy,
+            buildLogTransport,
             preparers,
             generators,
             publisher,

plugins/techdocs-node/api-report.md

@@ -16,6 +16,7 @@ import { Logger } from 'winston';
 import { PluginEndpointDiscovery } from '@backstage/backend-common';
 import { ScmIntegrationRegistry } from '@backstage/integration';
 import { UrlReader } from '@backstage/backend-common';
+import * as winston from 'winston';
 import { Writable } from 'stream';
 
 // @public
@@ -240,6 +241,8 @@ export type SupportedGeneratorKey = 'techdocs' | string;
 
 // @public
 export interface TechdocsBuildsExtensionPoint {
+  // (undocumented)
+  setBuildLogTransport(transport: winston.transport): void;
   // (undocumented)
   setBuildStrategy(buildStrategy: DocsBuildStrategy): void;
 }

plugins/techdocs-node/src/extensions.ts

@@ -16,6 +16,7 @@
 import { createExtensionPoint } from '@backstage/backend-plugin-api';
 import { DocsBuildStrategy } from './techdocsTypes';
 import { PreparerBase, RemoteProtocol, TechdocsGenerator } from './stages';
+import * as winston from 'winston';
 
 /**
  * Extension point type for configuring Techdocs builds.
@@ -24,6 +25,7 @@ import { PreparerBase, RemoteProtocol, TechdocsGenerator } from './stages';
  */
 export interface TechdocsBuildsExtensionPoint {
   setBuildStrategy(buildStrategy: DocsBuildStrategy): void;
+  setBuildLogTransport(transport: winston.transport): void;
 }
 
 /**