diff --git a/src/services/diskCache.ts b/src/services/diskCache.ts
index 042d2aa02..59a7085cf 100644
--- a/src/services/diskCache.ts
+++ b/src/services/diskCache.ts
@@ -1,11 +1,12 @@
-import path from 'path';
-import { readFile, writeFile, existsSync, unlink } from 'promise-fs';
 import DiskLRUService from '../services/diskLRU';
 import crypto from 'crypto';
+import { existsSync, readFile, writeFile, unlink } from 'promise-fs';
+import path from 'path';
+import { LimitedCache } from '../types/cache';
 
 const MAX_CACHE_SIZE = 1000 * 1000 * 1000; // 1GB
 
-export class DiskCache {
+export class DiskCache implements LimitedCache {
     constructor(private cacheBucketDir: string) {}
 
     async put(cacheKey: string, response: Response): Promise<void> {
diff --git a/src/types/cache.ts b/src/types/cache.ts
new file mode 100644
index 000000000..a5412f0eb
--- /dev/null
+++ b/src/types/cache.ts
@@ -0,0 +1,5 @@
+export interface LimitedCache {
+    match: (key: string) => Promise<Response>;
+    put: (key: string, data: Response) => Promise<void>;
+    delete: (key: string) => Promise<boolean>;
+}