# Google Cloud Storage driver An implementation of the `storagedriver.StorageDriver` interface which uses Google Cloud for object storage. ## Parameters

Parameter	Required	Description
bucket	yes	Storage bucket name.
keyfile	no	A private service account key file in JSON format. Instead of a key file Google Application Default Credentials can be used.
rootdirectory	no	This is a prefix that will be applied to all Google Cloud Storage keys to allow you to segment data in your bucket if necessary.
chunksize	no (default 5242880)	This is the chunk size used for uploading large blobs, must be a multiple of 256*1024.

`bucket`: The name of your Google Cloud Storage bucket where you wish to store objects (needs to already be created prior to driver initialization). `keyfile`: (optional) A private key file in JSON format, used for [Service Account Authentication](https://cloud.google.com/storage/docs/authentication#service_accounts). **Note** Instead of a key file you can use [Google Application Default Credentials](https://developers.google.com/identity/protocols/application-default-credentials). `rootdirectory`: (optional) The root directory tree in which all registry files will be stored. Defaults to the empty string (bucket root).