From 52d59981768057d7c64fc0d3e5b212c5000ee56c Mon Sep 17 00:00:00 2001
From: Tim Hansen <timbonicush@spotify.com>
Date: Wed, 17 May 2023 10:00:53 -0600
Subject: [PATCH] Default CacheClient to in-memory

Signed-off-by: Tim Hansen <timbonicush@spotify.com>
---
 .changeset/dirty-eels-poke.md                 |  5 +++
 .../src/cache/CacheManager.test.ts            | 13 ++++--
 .../backend-common/src/cache/CacheManager.ts  | 13 +-----
 packages/backend-common/src/cache/NoStore.ts  | 43 -------------------
 4 files changed, 16 insertions(+), 58 deletions(-)
 create mode 100644 .changeset/dirty-eels-poke.md
 delete mode 100644 packages/backend-common/src/cache/NoStore.ts

diff --git a/.changeset/dirty-eels-poke.md b/.changeset/dirty-eels-poke.md
new file mode 100644
index 0000000000..e2e3fa5066
--- /dev/null
+++ b/.changeset/dirty-eels-poke.md
@@ -0,0 +1,5 @@
+---
+'@backstage/backend-common': patch
+---
+
+Changed the default backend CacheClient to an in-memory cache when not explicitly configured.
diff --git a/packages/backend-common/src/cache/CacheManager.test.ts b/packages/backend-common/src/cache/CacheManager.test.ts
index 3239be4d0e..4578d4fed9 100644
--- a/packages/backend-common/src/cache/CacheManager.test.ts
+++ b/packages/backend-common/src/cache/CacheManager.test.ts
@@ -20,7 +20,6 @@ import KeyvMemcache from '@keyv/memcache';
 import KeyvRedis from '@keyv/redis';
 import { DefaultCacheClient } from './CacheClient';
 import { CacheManager } from './CacheManager';
-import { NoStore } from './NoStore';
 
 jest.createMockFromModule('keyv');
 jest.mock('keyv');
@@ -119,17 +118,23 @@ describe('CacheManager', () => {
   });
 
   describe('CacheManager.forPlugin stores', () => {
-    it('returns none client when no cache is configured', () => {
+    it('returns memory client when no cache is configured', () => {
       const manager = CacheManager.fromConfig(
         new ConfigReader({ backend: {} }),
       );
+      const expectedTtl = 3600;
       const expectedNamespace = 'test-plugin';
-      manager.forPlugin(expectedNamespace).getClient();
+      manager
+        .forPlugin(expectedNamespace)
+        .getClient({ defaultTtl: expectedTtl });
 
       const cache = Keyv as unknown as jest.Mock;
       const mockCalls = cache.mock.calls.splice(-1);
       const callArgs = mockCalls[0];
-      expect(callArgs[0].store).toBeInstanceOf(NoStore);
+      expect(callArgs[0]).toMatchObject({
+        ttl: expectedTtl,
+        namespace: expectedNamespace,
+      });
     });
 
     it('returns memory client when explicitly configured', () => {
diff --git a/packages/backend-common/src/cache/CacheManager.ts b/packages/backend-common/src/cache/CacheManager.ts
index 12ece42854..9101445b08 100644
--- a/packages/backend-common/src/cache/CacheManager.ts
+++ b/packages/backend-common/src/cache/CacheManager.ts
@@ -25,7 +25,6 @@ import {
 } from '@backstage/backend-plugin-api';
 import { getRootLogger } from '../logging';
 import { DefaultCacheClient } from './CacheClient';
-import { NoStore } from './NoStore';
 import { CacheManagerOptions, PluginCacheManager } from './types';
 
 /**
@@ -44,7 +43,6 @@ export class CacheManager {
     redis: this.getRedisClient,
     memcache: this.getMemcacheClient,
     memory: this.getMemoryClient,
-    none: this.getNoneClient,
   };
 
   /**
@@ -70,8 +68,8 @@ export class CacheManager {
     options: CacheManagerOptions = {},
   ): CacheManager {
     // If no `backend.cache` config is provided, instantiate the CacheManager
-    // with a "NoStore" cache client.
-    const store = config.getOptionalString('backend.cache.store') || 'none';
+    // with an in-memory cache client.
+    const store = config.getOptionalString('backend.cache.store') || 'memory';
     const connectionString =
       config.getOptionalString('backend.cache.connection') || '';
     const logger = (options.logger || getRootLogger()).child({
@@ -169,13 +167,6 @@ export class CacheManager {
       store: this.memoryStore,
     });
   }
-
-  private getNoneClient(pluginId: string): Keyv {
-    return new Keyv({
-      namespace: pluginId,
-      store: new NoStore(),
-    });
-  }
 }
 
 /** @public */
diff --git a/packages/backend-common/src/cache/NoStore.ts b/packages/backend-common/src/cache/NoStore.ts
deleted file mode 100644
index 85f789d21e..0000000000
--- a/packages/backend-common/src/cache/NoStore.ts
+++ /dev/null
@@ -1,43 +0,0 @@
-/*
- * Copyright 2021 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 { Store } from 'keyv';
-
-/**
- * Storage class compatible with Keyv which always results in a no-op. This is
- * used when no cache store is configured in a Backstage backend instance.
- */
-export class NoStore implements Store<string | undefined> {
-  clear(): void {
-    return;
-  }
-
-  delete(_key: string): boolean {
-    return false;
-  }
-
-  get(_key: string) {
-    return undefined;
-  }
-
-  has(_key: string): boolean {
-    return false;
-  }
-
-  set(_key: string, _value: any): this {
-    return this;
-  }
-}