Add support for Google Cloud Service universe domain

A customer needs support for Google Cloud Dedicated:
https://cloud.google.com/sovereign-cloud?hl=en

This supports the `universe_domain` setting added in
googleapis/google-api-go-client#2335.

Relates to https://gitlab.com/gitlab-org/gitlab/-/work_items/581881

Changelog: added

Author: stanhu

cache/gcsv2/adapter.go

@@ -79,6 +79,10 @@ func (a *gcsAdapter) presignURL(ctx context.Context, method string, contentType
 		options = append(options, option.WithoutAuthentication())
 	}
 
+	if a.config.UniverseDomain != "" {
+		options = append(options, option.WithUniverseDomain(a.config.UniverseDomain))
+	}
+
 	client, err := storage.NewClient(ctx, options...)
 	if err != nil {
 		return nil, fmt.Errorf("creating storage client: %w", err)

common/config.go

@@ -1195,6 +1195,7 @@ type CacheGCSConfig struct {
 	CacheGCSCredentials
 	CredentialsFile string `toml:"CredentialsFile,omitempty" long:"credentials-file" env:"GOOGLE_APPLICATION_CREDENTIALS" description:"File with GCP credentials, containing AccessID and PrivateKey"`
 	BucketName      string `toml:"BucketName,omitempty" long:"bucket-name" env:"CACHE_GCS_BUCKET_NAME" description:"Name of the bucket where cache will be stored"`
+	UniverseDomain  string `toml:"UniverseDomain,omitempty" long:"universe-domain" env:"CACHE_GCS_UNIVERSE_DOMAIN" description:"Universe Domain for GCS requests (e.g., googleapis.com for public cloud, or a custom universe domain)"`
 }
 
 type CacheS3Config struct {

common/config_test.go

@@ -22,6 +22,54 @@ import (
 	"gitlab.com/gitlab-org/gitlab-runner/helpers/process"
 )
 
+func TestCacheGCSConfig_UniverseDomain(t *testing.T) {
+	tests := map[string]struct {
+		config         string
+		expectedDomain string
+		validateConfig func(t *testing.T, config *Config)
+	}{
+		"universe domain not set": {
+			config: `
+[[runners]]
+	[runners.cache.gcs]
+		BucketName = "test-bucket"
+`,
+			expectedDomain: "",
+		},
+		"universe domain set to googleapis.com": {
+			config: `
+[[runners]]
+	[runners.cache.gcs]
+		BucketName = "test-bucket"
+		UniverseDomain = "googleapis.com"
+`,
+			expectedDomain: "googleapis.com",
+		},
+		"universe domain set to custom universe": {
+			config: `
+[[runners]]
+	[runners.cache.gcs]
+		BucketName = "test-bucket"
+		UniverseDomain = "custom.universe.com"
+`,
+			expectedDomain: "custom.universe.com",
+		},
+	}
+
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			cfg := NewConfig()
+			_, err := toml.Decode(tt.config, cfg)
+			assert.NoError(t, err)
+
+			require.Len(t, cfg.Runners, 1)
+			require.NotNil(t, cfg.Runners[0].Cache)
+			require.NotNil(t, cfg.Runners[0].Cache.GCS)
+			assert.Equal(t, tt.expectedDomain, cfg.Runners[0].Cache.GCS.UniverseDomain)
+		})
+	}
+}
+
 func TestCacheS3Config_AuthType(t *testing.T) {
 	tests := map[string]struct {
 		s3       CacheS3Config
@@ -2593,6 +2641,36 @@ func TestConfig_Masked(t *testing.T) {
 				},
 			},
 		},
+		"cache gcs universe domain": {
+			input: &Config{
+				Runners: []*RunnerConfig{
+					{
+						RunnerSettings: RunnerSettings{
+							Cache: &CacheConfig{
+								GCS: &CacheGCSConfig{
+									BucketName:     "test-bucket",
+									UniverseDomain: "googleapis.com",
+								},
+							},
+						},
+					},
+				},
+			},
+			expected: &Config{
+				Runners: []*RunnerConfig{
+					{
+						RunnerSettings: RunnerSettings{
+							Cache: &CacheConfig{
+								GCS: &CacheGCSConfig{
+									BucketName:     "test-bucket",
+									UniverseDomain: "googleapis.com",
+								},
+							},
+						},
+					},
+				},
+			},
+		},
 		"cache azure account key": {
 			input: &Config{
 				Runners: []*RunnerConfig{