add support for ghes caching

src/cache-utils.ts

@@ -1,5 +1,6 @@
 import * as core from '@actions/core';
 import * as exec from '@actions/exec';
+import * as cache from '@actions/cache';
 
 type SupportedPackageManagers = {
   [prop: string]: PackageManagerInfo;
@@ -95,3 +96,32 @@ export const getCacheDirectoryPath = async (
 
   return stdOut;
 };
+
+function logWarning(message: string): void {
+  const warningPrefix = '[warning]';
+  core.info(`${warningPrefix}${message}`);
+}
+
+export function isGhes(): boolean {
+  const ghUrl = new URL(
+    process.env['GITHUB_SERVER_URL'] || 'https://github.com'
+  );
+  return ghUrl.hostname.toUpperCase() !== 'GITHUB.COM';
+}
+
+export function isCacheFeatureAvailable(): boolean {
+  if (!cache.isFeatureAvailable()) {
+    if (isGhes()) {
+      logWarning(
+        'Cache action is only supported on GHES version >= 3.5. If you are on version >=3.5 Please check with GHES admin if Actions cache service is enabled or not.'
+      );
+    } else {
+      logWarning(
+        'An internal error has occurred in cache backend. Please check https://www.githubstatus.com/ for any ongoing issue in actions.'
+      );
+    }
+    return false;
+  }
+
+  return true;
+}