update deps

backend/vendor/cloud.google.com/go/compute/metadata/.repo-metadata.json

@@ -0,0 +1,12 @@
+{
+  "name": "metadata",
+  "name_pretty": "Google Compute Engine Metadata API",
+  "product_documentation": "https://cloud.google.com/compute/docs/storing-retrieving-metadata",
+  "client_documentation": "https://godoc.org/cloud.google.com/go/compute/metadata",
+  "release_level": "ga",
+  "language": "go",
+  "repo": "googleapis/google-cloud-go",
+  "distribution_name": "cloud.google.com/go/compute/metadata",
+  "api_id": "compute:metadata",
+  "requires_billing": false
+}

backend/vendor/cloud.google.com/go/compute/metadata/metadata.go

@@ -227,6 +227,9 @@ func InternalIP() (string, error) { return defaultClient.InternalIP() }
 // ExternalIP returns the instance's primary external (public) IP address.
 func ExternalIP() (string, error) { return defaultClient.ExternalIP() }
 
+// Email calls Client.Email on the default client.
+func Email(serviceAccount string) (string, error) { return defaultClient.Email(serviceAccount) }
+
 // Hostname returns the instance's hostname. This will be of the form
 // "<instanceID>.c.<projID>.internal".
 func Hostname() (string, error) { return defaultClient.Hostname() }
@@ -367,6 +370,16 @@ func (c *Client) InternalIP() (string, error) {
 	return c.getTrimmed("instance/network-interfaces/0/ip")
 }
 
+// Email returns the email address associated with the service account.
+// The account may be empty or the string "default" to use the instance's
+// main account.
+func (c *Client) Email(serviceAccount string) (string, error) {
+	if serviceAccount == "" {
+		serviceAccount = "default"
+	}
+	return c.getTrimmed("instance/service-accounts/" + serviceAccount + "/email")
+}
+
 // ExternalIP returns the instance's primary external (public) IP address.
 func (c *Client) ExternalIP() (string, error) {
 	return c.getTrimmed("instance/network-interfaces/0/access-configs/0/external-ip")