Support custom Azure Blob Storage domains

Users of Azure Blob Storage, particularly those in China, may need to
customize the Azure endpoint. This change introduces a
`azure_storage_domain` parameter to be passed in the connection storage
settings. By default, `blob.core.windows.net` will be used. Example
other mappings:

1. China: blob.core.chinacloudapi.cn
2. US Government: blob.core.usgovcloudapi.net
3. Germany: blob.cloudapi.de

This change requires Workhorse changes as well:
https://gitlab.com/gitlab-org/gitlab-workhorse/-/merge_requests/575.
Otherwise, the default domain will be used.

Documentation is in
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/40693.

Gemfile

@@ -119,7 +119,7 @@ gem 'fog-local', '~> 0.6'
 gem 'fog-openstack', '~> 1.0'
 gem 'fog-rackspace', '~> 0.1.1'
 gem 'fog-aliyun', '~> 0.3'
-gem 'gitlab-fog-azure-rm', '~> 0.7', require: false
+gem 'gitlab-fog-azure-rm', '~> 0.8', require: false
 
 # for Google storage
 gem 'google-api-client', '~> 0.33'

Gemfile.lock

@@ -419,7 +419,7 @@ GEM
     github-markup (1.7.0)
     gitlab-chronic (0.10.5)
       numerizer (~> 0.2)
-    gitlab-fog-azure-rm (0.7.0)
+    gitlab-fog-azure-rm (0.8.1)
       azure-storage (~> 0.15.0.preview)
       fog-core (= 2.1.0)
       fog-json (~> 1.2.0)
@@ -1303,7 +1303,7 @@ DEPENDENCIES
   gitaly (~> 13.3.0.pre.rc1)
   github-markup (~> 1.7.0)
   gitlab-chronic (~> 0.10.5)
-  gitlab-fog-azure-rm (~> 0.7)
+  gitlab-fog-azure-rm (~> 0.8)
   gitlab-labkit (= 0.12.1)
   gitlab-license (~> 1.0)
   gitlab-mail_room (~> 0.0.6)

changelogs/unreleased/sh-azure-custom-domains.yml

+---
+title: Support custom Azure Blob Storage domains
+merge_request: 40694
+author:
+type: added

lib/object_storage/config.rb

@@ -54,6 +54,12 @@ module ObjectStorage
     end
     # End AWS-specific options
 
+    # Begin Azure-specific options
+    def azure_storage_domain
+      credentials[:azure_storage_domain]
+    end
+    # End Azure-specific options
+
     def google?
       provider == 'Google'
     end

lib/object_storage/direct_upload.rb

@@ -98,6 +98,9 @@ module ObjectStorage
         RemoteTempObjectID: object_name,
         ObjectStorage: {
           Provider: 'AzureRM',
+          AzureConfig: {
+            StorageDomain: config.azure_storage_domain
+          },
           GoCloudConfig: {
             URL: "azblob://#{bucket_name}"
           }

spec/lib/object_storage/direct_upload_spec.rb

@@ -211,6 +211,7 @@ RSpec.describe ObjectStorage::DirectUpload do
         expect(subject[:UseWorkhorseClient]).to be true
         expect(subject[:RemoteTempObjectID]).to eq(object_name)
         expect(subject[:ObjectStorage][:Provider]).to eq('AzureRM')
+        expect(subject[:ObjectStorage][:AzureConfig][:StorageDomain]).to eq(storage_domain)
         expect(subject[:ObjectStorage][:GoCloudConfig]).to eq({ URL: "azblob://#{bucket_name}" })
       end
     end
@@ -395,20 +396,22 @@ RSpec.describe ObjectStorage::DirectUpload do
         }
       end
 
+      let(:has_length) { false }
+      let(:storage_domain) { nil }
       let(:storage_url) { 'https://azuretest.blob.core.windows.net' }
 
-      context 'when length is known' do
-        let(:has_length) { true }
+      it_behaves_like 'a valid AzureRM upload'
+      it_behaves_like 'a valid upload without multipart data'
 
-        it_behaves_like 'a valid AzureRM upload'
-        it_behaves_like 'a valid upload without multipart data'
-      end
+      context 'when a custom storage domain is used' do
+        let(:storage_domain) { 'blob.core.chinacloudapi.cn' }
+        let(:storage_url) { "https://azuretest.#{storage_domain}" }
 
-      context 'when length is unknown' do
-        let(:has_length) { false }
+        before do
+          credentials[:azure_storage_domain] = storage_domain
+        end
 
         it_behaves_like 'a valid AzureRM upload'
-        it_behaves_like 'a valid upload without multipart data'
       end
     end
   end