[rush-azure-storage-build-cache-plugin] Add custom endpoint support via storageEndpoint (#5664)

* add optional storageEndpoint config

* add change

* Update common/changes/@microsoft/rush/feat-custom-endpoint-azure-blob-storage_2026-02-23-03-40.json

Co-authored-by: Ian Clanton-Thuon <iclanton@users.noreply.github.com>

---------

Co-authored-by: Ian Clanton-Thuon <iclanton@users.noreply.github.com>

Author: ryceg

common/changes/@microsoft/rush/feat-custom-endpoint-azure-blob-storage_2026-02-23-03-40.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@microsoft/rush",
+      "comment": "Add custom endpoint support via a `storageEndpoint` configuration option for the Azure Storage build cache plugin.",
+      "type": "none"
+    }
+  ],
+  "packageName": "@microsoft/rush"
+}

common/reviews/api/rush-azure-storage-build-cache-plugin.api.md

@@ -98,6 +98,8 @@ export interface IAzureStorageAuthenticationOptions extends IAzureAuthentication
     storageAccountName: string;
     // (undocumented)
     storageContainerName: string;
+    // (undocumented)
+    storageEndpoint?: string;
 }
 
 // @public (undocumented)

rush-plugins/rush-azure-storage-build-cache-plugin/src/AzureStorageAuthentication.ts

@@ -24,6 +24,7 @@ import {
 export interface IAzureStorageAuthenticationOptions extends IAzureAuthenticationBaseOptions {
   storageContainerName: string;
   storageAccountName: string;
+  storageEndpoint?: string;
   isCacheWriteAllowed: boolean;
 }
 
@@ -46,7 +47,11 @@ export class AzureStorageAuthentication extends AzureAuthenticationBase {
     this._storageAccountName = options.storageAccountName;
     this._storageContainerName = options.storageContainerName;
     this._isCacheWriteAllowedByConfiguration = options.isCacheWriteAllowed;
-    this._storageAccountUrl = `https://${this._storageAccountName}.blob.core.windows.net/`;
+    this._storageAccountUrl = options.storageEndpoint
+      ? options.storageEndpoint.endsWith('/')
+        ? options.storageEndpoint
+        : options.storageEndpoint + '/'
+      : `https://${this._storageAccountName}.blob.core.windows.net/`;
   }
 
   protected _getCacheIdParts(): string[] {

rush-plugins/rush-azure-storage-build-cache-plugin/src/RushAzureStorageBuildCachePlugin.ts

@@ -37,6 +37,13 @@ interface IAzureBlobStorageConfigurationJson {
    */
   readonly loginFlowFailover?: LoginFlowFailoverMap;
 
+  /**
+   * An optional custom endpoint URL for the Azure Blob Storage account.
+   * Use this to connect to Azurite, private endpoints, or storage emulators.
+   * Overrides the default endpoint derived from storageAccountName.
+   */
+  readonly storageEndpoint?: string;
+
   /**
    * An optional prefix for cache item blob names.
    */
@@ -70,6 +77,7 @@ export class RushAzureStorageBuildCachePlugin implements IRushPlugin {
         return new AzureStorageBuildCacheProvider({
           storageAccountName: azureBlobStorageConfiguration.storageAccountName,
           storageContainerName: azureBlobStorageConfiguration.storageContainerName,
+          storageEndpoint: azureBlobStorageConfiguration.storageEndpoint,
           azureEnvironment: azureBlobStorageConfiguration.azureEnvironment,
           blobPrefix: azureBlobStorageConfiguration.blobPrefix,
           loginFlow: azureBlobStorageConfiguration.loginFlow,

rush-plugins/rush-azure-storage-build-cache-plugin/src/schemas/azure-blob-storage-config.schema.json

@@ -95,6 +95,12 @@
       "description": "An optional prefix for cache item blob names."
     },
 
+    "storageEndpoint": {
+      "type": "string",
+      "description": "An optional custom endpoint URL for the Azure Blob Storage account. Use this to connect to Azurite, private endpoints, or storage emulators. When specified, this overrides the default endpoint derived from storageAccountName. Example: \"http://127.0.0.1:10000/devstoreaccount1\" or \"https://my-proxy.example.com/devstoreaccount1\"",
+      "format": "uri"
+    },
+
     "isCacheWriteAllowed": {
       "type": "boolean",
       "description": "If set to true, allow writing to the cache. Defaults to false."

rush-plugins/rush-azure-storage-build-cache-plugin/src/test/AzureStorageBuildCacheProvider.test.ts

@@ -31,6 +31,40 @@ describe(AzureStorageBuildCacheProvider.name, () => {
     ).toThrowErrorMatchingSnapshot();
   });
 
+  describe('storageEndpoint', () => {
+    it('uses the default endpoint when storageEndpoint is not provided', () => {
+      const subject: AzureStorageBuildCacheProvider = new AzureStorageBuildCacheProvider({
+        storageAccountName: 'storage-account',
+        storageContainerName: 'container-name',
+        isCacheWriteAllowed: false
+      });
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      expect((subject as any)._storageAccountUrl).toBe('https://storage-account.blob.core.windows.net/');
+    });
+
+    it('uses the custom endpoint when storageEndpoint is provided', () => {
+      const subject: AzureStorageBuildCacheProvider = new AzureStorageBuildCacheProvider({
+        storageAccountName: 'devstoreaccount1',
+        storageContainerName: 'container-name',
+        storageEndpoint: 'http://127.0.0.1:10000/devstoreaccount1',
+        isCacheWriteAllowed: false
+      });
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      expect((subject as any)._storageAccountUrl).toBe('http://127.0.0.1:10000/devstoreaccount1/');
+    });
+
+    it('preserves a trailing slash on the custom endpoint', () => {
+      const subject: AzureStorageBuildCacheProvider = new AzureStorageBuildCacheProvider({
+        storageAccountName: 'devstoreaccount1',
+        storageContainerName: 'container-name',
+        storageEndpoint: 'https://my-proxy.example.com/devstoreaccount1/',
+        isCacheWriteAllowed: false
+      });
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      expect((subject as any)._storageAccountUrl).toBe('https://my-proxy.example.com/devstoreaccount1/');
+    });
+  });
+
   describe('isCacheWriteAllowed', () => {
     function prepareSubject(
       optionValue: boolean,