Reference GCloud Pub/Sub src in GCloud storage doc

Author: antoineco

docs/images/googlecloudstorage-source/iam-1.png renamed to docs/images/googlecloudpubsub-source/iam-1.png

@@ -29,8 +29,7 @@ that topic are provided in the [Pub/Sub Subscription](#pubsub-subscription-optio
 The predefined `roles/pubsub.editor` role is one example of role that is suitable for use with the TriggerMesh event
 source for Google Cloud Pub/Sub.
 
-<!-- NOTE(antoineco): image from googlecloudstorage source purposely reused for simplicity -->
-![Service account](../images/googlecloudstorage-source/iam-1.png)
+![Service account](../images/googlecloudpubsub-source/iam-1.png)
 
 Create a [key][gc-iam-key] for this service account and save it. This key must be in JSON format. It is required to be
 able to run an instance of the Google Cloud Pub/Sub event source.
@@ -43,8 +42,7 @@ and subscriptions][gc-pubsub-adm].
 Take note of the full [topic name][gc-pubsub-resname], it is a required input to be able to run an instance of the
 Google Cloud Pub/Sub event source.
 
-<!-- NOTE(antoineco): image from googlecloudstorage source purposely reused for simplicity -->
-![Topic](../images/googlecloudstorage-source/topic-1.png)
+![Topic](../images/googlecloudpubsub-source/topic-1.png)
 
 ### Pub/Sub Subscription _(optional)_
 
@@ -59,8 +57,7 @@ If, however, you prefer messages to be pulled using a subscription which you man
 subscription is a "pull" subscription as described in the documentation page [Managing topics and
 subscriptions][gc-pubsub-adm].
 
-<!-- NOTE(antoineco): image from googlecloudstorage source purposely reused for simplicity -->
-![Subscription](../images/googlecloudstorage-source/subscription-1.png)
+![Subscription](../images/googlecloudpubsub-source/subscription-1.png)
 
 ## Deploying an Instance of the Source
 

docs/images/googlecloudstorage-source/subscription-1.png renamed to docs/images/googlecloudpubsub-source/subscription-1.png

@@ -5,44 +5,30 @@ to a [Google Cloud Pub/Sub][gc-storage-events] topic.
 
 ## Prerequisite(s)
 
+- Event Source for Google Cloud Pub/Sub
 - Storage Bucket
-- Pub/Sub Topic and Subscription
 - Notification Configuration
-- Service Account
 
-### Storage Bucket
-
-The storage bucket is expected to exist prior to running this event source. If you haven't already done so, create a
-bucket by following the instructions from the [Cloud Storage How-To Guides][gc-storage-howto].
-
-### Pub/Sub Topic and Subscription
-
-A Pub/Sub topic is required to be able to consume change notifications from Cloud Storage.
+### Event Source for Google Cloud Pub/Sub
 
-You can either create this topic manually by following the instructions at [Managing topics and
-subscriptions][gc-pubsub-adm], or instead use the [`gsutil`][gsutil] command-line tool to create the Pub/Sub topic and
-add a notification configuration to the bucket in a single step, as described at [Using Pub/Sub notifications for Cloud
-Storage][gc-storage-setup].
+Change notifications from Cloud Storage buckets can not be consumed directly, but are instead sent to a Google Cloud
+Pub/Sub topic. Follow the instructions at [Event Source for Google Cloud Storage](./googlecloudpubsub.md) for setting up
+a Pub/Sub topic and running an instance of the Pub/Sub event source.
 
-![Topic](../images/googlecloudstorage-source/topic-1.png)
-
-Once a topic exists, it is necessary to create a _subscription_ in order to allow the TriggerMesh event source for
-Google Cloud Storage to pull events from this topic. The documentation page [Managing topics and
-subscriptions][gc-pubsub-adm] explains this procedure in details.
+!!! note
+    As an alternative to a manual creation, the Pub/Sub topic will be created automatically while enabling the
+    [Notification Configuration](#notification-configuration) if it doesn't already exist.
 
-Take note of the name of this subscription, it is a required input to be able to run an instance of the Google Cloud
-Storage event source.
+### Storage Bucket
 
-![Subscription](../images/googlecloudstorage-source/subscription-1.png)
+You can create a Cloud Storage bucket by following the instructions from the [Cloud Storage How-To
+Guides][gc-storage-howto].
 
 ### Notification Configuration
 
-Change notifications need to be enabled in the selected bucket by applying a _notification configuration_.
-
-If you have already followed the instructions from the previous section and applied a notification configuration at the
-same time as you created the Pub/Sub topic using `gsutil`, your bucket is already configured for sending events.
-Otherwise, follow the instructions at [Using Pub/Sub notifications for Cloud Storage][gc-storage-setup] and add a new
-notification configuration.
+Change notifications need to be enabled in the selected bucket by applying a _notification configuration_. Follow the
+instructions at [Using Pub/Sub notifications for Cloud Storage][gc-storage-setup] to add a new notification
+configuration using the [`gsutil`][gsutil] command-line tool.
 
 Below is an example of command which applies a notification configuration to a bucket called `eventsource-dev`, with a
 Pub/Sub topic called `triggermesh-storage-source` set as event destination.
@@ -62,62 +48,9 @@ projects/_/buckets/eventsource-dev/notificationConfigs/1
 !!! note
     It is currently not possible to manage Pub/Sub notifications via the Cloud Console.
 
-### Service Account
-
-A [Service Account][gc-storage-svcacc] is required to authenticate the event source and allow it to interact with Google
-Cloud Pub/Sub. You can create a service account by following the instructions at [Creating and managing service
-accounts][gc-iam-svcacc].
-
-The service account must be granted an [IAM Role][gc-iam-roles] with at least the following permission:
-
-- `pubsub.subscriptions.consume`
-
-The predefined `roles/pubsub.subscriber` role is one example of role that is suitable for use with the TriggerMesh event
-source for Google Cloud Storage.
-
-![Service account](../images/googlecloudstorage-source/iam-1.png)
-
-Create a [key][gc-iam-key] for this service account and save it. This key must be in JSON format. It is required to be
-able to run an instance of the Google Cloud Storage event source.
-
-## Deploying an Instance of the Source
-
-Open the Bridge creation screen and add a source of type `Google Cloud Storage`.
-
-![Adding a Google Cloud Storage source](../images/googlecloudstorage-source/create-bridge-1.png)
-
-In the Source creation form, give a name to the event source and add the following information:
-
-- [**Secret**][gc-iam-key]: Service account key in JSON format, as described in the previous sections.
-- **Google Cloud project name**: Name of the Google Cloud project containing the storage bucket.
-- **Pub/Sub Subscription name**: Name of a Pub/Sub subscription which pulls messages from the topic where the Cloud
-  Storage bucket sends its change notifications.
-
-![Google Cloud Storage source form](../images/googlecloudstorage-source/create-bridge-2.png)
-
-After clicking the `Save` button, you will be taken back to the Bridge editor. Proceed to adding the remaining
-components to the Bridge, then submit it.
-
-![Bridge overview](../images/googlecloudstorage-source/create-bridge-3.png)
-
-A ready status on the main _Bridges_ page indicates that the event source is ready to consume Cloud Storage
-notifications from the Pub/Sub topic.
-
-![Bridge status](../images/googlecloudstorage-source/create-bridge-4.png)
-
-## Event Types
-
-The TriggerMesh event source for Google Cloud Storage emits events of the following type:
-
-- `com.triggermesh.googlecloudstorage.event`
-
 [gc-storage]: https://cloud.google.com/storage/docs/introduction
 [gc-storage-events]: https://cloud.google.com/storage/docs/pubsub-notifications
 [gc-storage-howto]: https://cloud.google.com/storage/docs/how-to
 [gc-storage-svcacc]: https://cloud.google.com/storage/docs/projects#service-accounts
 [gc-storage-setup]: https://cloud.google.com/storage/docs/reporting-changes
-[gc-iam-svcacc]: https://cloud.google.com/iam/docs/creating-managing-service-accounts
-[gc-iam-key]: https://cloud.google.com/iam/docs/creating-managing-service-account-keys
-[gc-iam-roles]: https://cloud.google.com/iam/docs/understanding-roles
-[gc-pubsub-adm]: https://cloud.google.com/pubsub/docs/admin
 [gsutil]: https://cloud.google.com/storage/docs/gsutil