Merge pull request #25094 from codingdiaz/catalog-error-docs

docs: update catalog error eventing/logging

.changeset/ten-pots-walk.md

@@ -0,0 +1,8 @@
+---
+'@backstage/plugin-catalog-backend-module-logs': patch
+---
+
+Creates a new module to make logging catalog errors simple. This module subscribes to catalog events and logs them.
+
+See [Backstage documentation](https://backstage.io/docs/features/software-catalog/configuration#subscribing-to-catalog-errors) for details on how to install
+and configure the plugin.

docs/features/software-catalog/configuration.md

@@ -177,3 +177,106 @@ here.
 Setting this value too low risks exhausting rate limits on external systems that
 are queried by processors, such as version control systems housing catalog-info
 files.
+
+## Subscribing to Catalog Errors
+
+Catalog errors are published to the [events plugin](https://github.com/backstage/backstage/tree/master/plugins/events-node): `@backstage/plugin-events-node`. You can subscribe to events and respond to errors, for example you may wish to log them.
+
+The first step is to add the events backend plugin to your Backstage application. Navigate to your Backstage application directory and add the plugin package.
+
+```ts
+# From your Backstage root directory
+yarn --cwd packages/backend add @backstage/plugin-events-node
+```
+
+Now you can install the events backend plugin in your backend.
+
+```ts title="packages/backend/src/index.ts"
+backend.add(import('@backstage/plugin-events-backend/alpha'));
+```
+
+### Logging Errors
+
+If you want to log catalog errors you can install the `@backstage/plugin-catalog-backend-module-logs` module.
+
+Install the catalog logs module.
+
+```ts
+# From your Backstage root directory
+yarn --cwd packages/backend add @backstage/plugin-catalog-backend-module-logs
+```
+
+Add the module to your backend.
+
+```ts title="packages/backend/src/index.ts"
+backend.add(import('@backstage/plugin-catalog-backend-module-logs'));
+```
+
+This will log errors with a level of `warn`.
+
+You should now see logs as the catalog emits events. Example:
+
+```
+[1] 2024-06-07T00:00:28.787Z events warn Policy check failed for user:default/guest; caused by Error: Malformed envelope, /metadata/tags must be array entity=user:default/guest location=file:/Users/foobar/code/backstage-demo-instance/examples/org.yaml
+```
+
+### Custom Error Handling
+
+If you wish to handle catalog errors with specific logic different from logging the errors the following should help you get started. For example, you may wish to send a notification or create a ticket for someone to investigate.
+
+Create a backend module that subscribes to the catalog error events. The topic is `experimental.catalog.errors`.
+
+```ts title="packages/backend/src/index.ts"
+import { CATALOG_ERRORS_TOPIC } from '@backstage/plugin-catalog-backend';
+import {
+  coreServices,
+  createBackendModule,
+} from '@backstage/backend-plugin-api';
+import { eventsServiceRef, EventParams } from '@backstage/plugin-events-node';
+
+interface EventsPayload {
+  entity: string;
+  location?: string;
+  errors: Error[];
+}
+
+interface EventsParamsWithPayload extends EventParams {
+  eventPayload: EventsPayload;
+}
+
+const eventsModuleCatalogErrors = createBackendModule({
+  pluginId: 'events',
+  moduleId: 'catalog-errors',
+  register(env) {
+    env.registerInit({
+      deps: {
+        events: eventsServiceRef,
+        logger: coreServices.logger,
+      },
+      async init({ events, logger }) {
+        events.subscribe({
+          id: 'catalog',
+          topics: [CATALOG_ERRORS_TOPIC],
+          async onEvent(params: EventParams): Promise<void> {
+            const event = params as EventsParamsWithPayload;
+            const { entity, location, errors } = event.eventPayload;
+            // Add custom logic here for responding to errors
+            for (const error of errors) {
+              logger.warn(error.message, {
+                entity,
+                location,
+              });
+            }
+          },
+        });
+      },
+    });
+  },
+});
+```
+
+Now install your module.
+
+```ts title="packages/backend/src/index.ts"
+backend.add(eventsModuleCatalogErrors);
+```

docs/features/software-catalog/life-of-an-entity.md

@@ -197,13 +197,15 @@ cannot be parsed successfully, etc.
 
 There are two main ways that these errors are surfaced.
 
-First, the catalog backend will produce detailed logs that should contain
-sufficient information for a reader to find the causes for errors. Since these
-logs are typically not easily found by end users, this can mainly be a useful
+First, the catalog backend will emit events using the [events backend plugin](https://github.com/backstage/backstage/tree/master/plugins/events-node). You can subscribe to the events. The events should contain
+sufficient information for a reader to find the causes for errors. See the [configuration documentation](./configuration.md#subscribing-to-catalog-errors) for how to subscribe and log these error events.
+Since these events are typically not easily found by end users, this can mainly be a useful
 tool for Backstage operators who want to debug problems either with statically
 registered entities that are under their control, or to help end users find
 problems.
 
+> Prior to Backstage version v1.26.0 and `@backstage/plugin-catalog-backend` v1.21.9 catalog errors were logged by default.
+
 Second, for most classes of errors, the entity itself will contain a status
 field that describes the problem. The contents of this field is shown at the top
 of your entity page in Backstage, if you have placed the corresponding error

plugins/catalog-backend-module-logs/.eslintrc.js

@@ -0,0 +1 @@
+module.exports = require('@backstage/cli/config/eslint-factory')(__dirname);

plugins/catalog-backend-module-logs/README.md

@@ -0,0 +1,8 @@
+# backstage-plugin-catalog-backend-module-logs
+
+A module that subscribes to catalog related events and logs them.
+
+## Getting started
+
+See [Backstage documentation](https://backstage.io/docs/features/software-catalog/configuration#subscribing-to-catalog-errors) for details on how to install
+and configure the plugin.

plugins/catalog-backend-module-logs/api-report.md

@@ -0,0 +1,11 @@
+## API Report File for "@backstage/plugin-catalog-backend-module-logs"
+
+> Do not edit this file. It is a report generated by [API Extractor](https://api-extractor.com/).
+
+```ts
+import { BackendFeatureCompat } from '@backstage/backend-plugin-api';
+
+// @public
+const catalogModuleLogs: BackendFeatureCompat;
+export default catalogModuleLogs;
+```

plugins/catalog-backend-module-logs/catalog-info.yaml

@@ -0,0 +1,10 @@
+apiVersion: backstage.io/v1alpha1
+kind: Component
+metadata:
+  name: backstage-plugin-catalog-backend-module-logs
+  title: '@backstage/plugin-catalog-backend-module-logs'
+  description: A module that subscribes to catalog releated events and logs them.
+spec:
+  lifecycle: experimental
+  type: backstage-backend-plugin-module
+  owner: maintainers

plugins/catalog-backend-module-logs/package.json

@@ -0,0 +1,45 @@
+{
+  "name": "@backstage/plugin-catalog-backend-module-logs",
+  "version": "0.0.0",
+  "description": "A module that subscribes to catalog releated events and logs them.",
+  "backstage": {
+    "role": "backend-plugin-module",
+    "pluginId": "catalog",
+    "pluginPackage": "@backstage/plugin-catalog-backend"
+  },
+  "publishConfig": {
+    "access": "public",
+    "main": "dist/index.cjs.js",
+    "types": "dist/index.d.ts"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/backstage/backstage",
+    "directory": "plugins/catalog-backend-module-logs"
+  },
+  "license": "Apache-2.0",
+  "main": "src/index.ts",
+  "types": "src/index.ts",
+  "files": [
+    "dist"
+  ],
+  "scripts": {
+    "build": "backstage-cli package build",
+    "clean": "backstage-cli package clean",
+    "lint": "backstage-cli package lint",
+    "prepack": "backstage-cli package prepack",
+    "postpack": "backstage-cli package postpack",
+    "start": "backstage-cli package start",
+    "test": "backstage-cli package test"
+  },
+  "dependencies": {
+    "@backstage/backend-plugin-api": "workspace:^",
+    "@backstage/plugin-catalog-backend": "workspace:^",
+    "@backstage/plugin-events-node": "workspace:^"
+  },
+  "devDependencies": {
+    "@backstage/backend-test-utils": "workspace:^",
+    "@backstage/cli": "workspace:^",
+    "@backstage/plugin-events-backend-test-utils": "workspace:^"
+  }
+}

plugins/catalog-backend-module-logs/src/index.ts

@@ -0,0 +1,22 @@
+/*
+ * Copyright 2024 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * A catalog module that logs catalog errors using the logger service.
+ *
+ * @packageDocumentation
+ */
+export { catalogModuleLogs as default } from './module';

plugins/catalog-backend-module-logs/src/module.test.ts

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2024 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { mockServices, startTestBackend } from '@backstage/backend-test-utils';
+import { catalogModuleLogs } from './module';
+import { createServiceFactory } from '@backstage/backend-plugin-api';
+import { TestEventsService } from '@backstage/plugin-events-backend-test-utils';
+import { eventsServiceRef } from '@backstage/plugin-events-node';
+
+describe('catalogModuleLogs', () => {
+  it('should be correctly wired and set up', async () => {
+    const events = new TestEventsService();
+    const eventsServiceFactory = createServiceFactory({
+      service: eventsServiceRef,
+      deps: {},
+      async factory({}) {
+        return events;
+      },
+    });
+
+    await startTestBackend({
+      features: [
+        mockServices.logger.factory(),
+        eventsServiceFactory(),
+        catalogModuleLogs(),
+      ],
+    });
+
+    expect(events.subscribed).toHaveLength(1);
+    expect(events.subscribed[0].id).toEqual('catalog');
+  });
+});

plugins/catalog-backend-module-logs/src/module.ts

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2024 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {
+  coreServices,
+  createBackendModule,
+} from '@backstage/backend-plugin-api';
+import { CATALOG_ERRORS_TOPIC } from '@backstage/plugin-catalog-backend';
+import { eventsServiceRef, EventParams } from '@backstage/plugin-events-node';
+
+interface EventsPayload {
+  entity: string;
+  location?: string;
+  errors: Error[];
+}
+
+interface EventsParamsWithPayload extends EventParams {
+  eventPayload: EventsPayload;
+}
+
+/**
+ * A catalog module that logs catalog errors using the logger service.
+ *
+ * @packageDocumentation
+ * @public
+ */
+export const catalogModuleLogs = createBackendModule({
+  pluginId: 'catalog',
+  moduleId: 'logs',
+  register(env) {
+    env.registerInit({
+      deps: {
+        events: eventsServiceRef,
+        logger: coreServices.logger,
+      },
+      async init({ events, logger }) {
+        events.subscribe({
+          id: 'catalog',
+          topics: [CATALOG_ERRORS_TOPIC],
+          async onEvent(params: EventParams): Promise<void> {
+            const event = params as EventsParamsWithPayload;
+            const { entity, location, errors } = event.eventPayload;
+            for (const error of errors) {
+              logger.warn(error.message, {
+                entity,
+                location,
+              });
+            }
+          },
+        });
+      },
+    });
+  },
+});

yarn.lock

@@ -5440,6 +5440,19 @@ __metadata:
   languageName: unknown
   linkType: soft
 
+"@backstage/plugin-catalog-backend-module-logs@workspace:plugins/catalog-backend-module-logs":
+  version: 0.0.0-use.local
+  resolution: "@backstage/plugin-catalog-backend-module-logs@workspace:plugins/catalog-backend-module-logs"
+  dependencies:
+    "@backstage/backend-plugin-api": "workspace:^"
+    "@backstage/backend-test-utils": "workspace:^"
+    "@backstage/cli": "workspace:^"
+    "@backstage/plugin-catalog-backend": "workspace:^"
+    "@backstage/plugin-events-backend-test-utils": "workspace:^"
+    "@backstage/plugin-events-node": "workspace:^"
+  languageName: unknown
+  linkType: soft
+
 "@backstage/plugin-catalog-backend-module-msgraph@workspace:plugins/catalog-backend-module-msgraph":
   version: 0.0.0-use.local
   resolution: "@backstage/plugin-catalog-backend-module-msgraph@workspace:plugins/catalog-backend-module-msgraph"