Add cache restore dryRun option

packages/cache/src/options.ts

@@ -53,6 +53,15 @@ export interface DownloadOptions {
    * @default 3600000
    */
   segmentTimeoutInMs?: number
+
+  /**
+   * Weather to skip downloading the cache entry.
+   * If dryRun is set to true, the restore function will only check if
+   * a matching cache entry exists and return the cache key if it does.
+   *
+   * @default false
+   */
+  dryRun?: boolean
 }
 
 /**
@@ -92,7 +101,8 @@ export function getDownloadOptions(copy?: DownloadOptions): DownloadOptions {
     useAzureSdk: true,
     downloadConcurrency: 8,
     timeoutInMs: 30000,
-    segmentTimeoutInMs: 3600000
+    segmentTimeoutInMs: 3600000,
+    dryRun: false
   }
 
   if (copy) {
@@ -111,6 +121,10 @@ export function getDownloadOptions(copy?: DownloadOptions): DownloadOptions {
     if (typeof copy.segmentTimeoutInMs === 'number') {
       result.segmentTimeoutInMs = copy.segmentTimeoutInMs
     }
+
+    if (typeof copy.dryRun === 'boolean') {
+      result.dryRun = copy.dryRun
+    }
   }
   const segmentDownloadTimeoutMins =
     process.env['SEGMENT_DOWNLOAD_TIMEOUT_MINS']
@@ -129,6 +143,7 @@ export function getDownloadOptions(copy?: DownloadOptions): DownloadOptions {
     `Cache segment download timeout mins env var: ${process.env['SEGMENT_DOWNLOAD_TIMEOUT_MINS']}`
   )
   core.debug(`Segment download timeout (ms): ${result.segmentTimeoutInMs}`)
+  core.debug(`Dry run: ${result.dryRun}`)
 
   return result
 }