Storage driver for: Google Cloud Storage (gcs)

Signed-off-by: Arthur Baars <arthur@semmle.com>

docs/configuration.md

@@ -82,6 +82,10 @@ information about each option that appears later in this page.
         accountname: accountname
         accountkey: base64encodedaccountkey
         container: containername
+      gcs:
+        bucket: bucketname
+        keyfile: /path/to/keyfile
+        rootdirectory: /gcs/object/name/prefix
       s3:
         accesskey: awsaccesskey
         secretkey: awssecretkey
@@ -330,6 +334,10 @@ Permitted values are `error`, `warn`, `info` and `debug`. The default is
         accountname: accountname
         accountkey: base64encodedaccountkey
         container: containername
+      gcs:
+        bucket: bucketname
+        keyfile: /path/to/keyfile
+        rootdirectory: /gcs/object/name/prefix
       s3:
         accesskey: awsaccesskey
         secretkey: awssecretkey
@@ -482,6 +490,50 @@ This storage backend uses Microsoft's Azure Blob Storage.
 
 </table>
 
+# gcs
+
+This storage backend uses Google Cloud Storage.
+
+<table>
+  <tr>
+    <th>Parameter</th>
+    <th>Required</th>
+    <th>Description</th>
+  </tr>
+  <tr>
+    <td>
+      <code>bucket</code>
+    </td>
+    <td>
+      yes
+    </td>
+    <td>
+      Storage bucket name.
+    </td>
+  </tr>
+  <tr>
+    <td>
+      <code>keyfile</code>
+    </td>
+    <td>
+      no
+    </td>
+    <td>
+      A private service account key file in JSON format. Instead of a key file <a href="https://developers.google.com/identity/protocols/application-default-credentials">Google Application Default Credentials</a> can be used.
+    </td>
+  </tr>
+   <tr>
+    <td>
+      <code>rootdirectory</code>
+    </td>
+    <td>
+      no
+    </td>
+    <td>
+      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.
+  </tr>
+
+</table>
 
 ### rados
 

docs/storage-drivers/gcs.md

@@ -0,0 +1,22 @@
+<!--[metadata]>
++++
+title = "GCS storage driver"
+description = "Explains how to use the Google Cloud Storage drivers"
+keywords = ["registry, service, driver, images, storage,  gcs, google, cloud"]
++++
+<![end-metadata]-->
+
+
+# Google Cloud Storage driver
+
+An implementation of the `storagedriver.StorageDriver` interface which uses Google Cloud for object storage.
+
+## Parameters
+
+`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).

docs/storagedrivers.md

@@ -24,6 +24,7 @@ This storage driver package comes bundled with several drivers:
 - [rados](storage-drivers/rados.md): A driver storing objects in a [Ceph Object Storage](http://ceph.com/docs/master/rados/) pool.
 - [swift](storage-drivers/swift.md): A driver storing objects in [Openstack Swift](http://docs.openstack.org/developer/swift/).
 - [oss](storage-drivers/oss.md): A driver storing objects in [Aliyun OSS](http://www.aliyun.com/product/oss).
+- [gcs](storage-drivers/gcs.md): A driver storing objects in a [Google Cloud Storage](https://cloud.google.com/storage/) bucket.
 
 ## Storage Driver API