Overview of Events and the SAP Alert Notification System

Cloud foundry events refer to actions taken against Cloud Foundry resources (services, applications, etc.) whether by a user or the system itself. Events are generated e.g. when an app starts, stops, and crashes, among other actions. Events give more detailed information about what has happened to a resource and they can be useful for troubleshooting.

To see all events in relation to the cf-nodejs application you created in the previous tutorials, first make sure the application is started, and then run:

cf events cf-nodejs

You will be greeted by output showing the last 50 events that have occurred in relation to the application.

With the cf events command you see only those events related to the app you specify, but using the Cloud Foundry API you can see all the events you have access to in Cloud Foundry.

The latest version of the API is v3, which is what will be referenced in this tutorial. All other versions are deprecated.

To see all the audit events, which you have access to, run:

cf curl /v3/audit_events

The generated list of events from this command will be for all organizations and spaces you have access to. You can filter these results further with the options listed in the API docs. E.g. to get the audit events for a dedicated space you can run:

cf space <space-name> --guid
cf curl "/v3/audit_events?space_guids=<space-guid>"

Be aware that there is pagination and you may need to iterate over the pages.

Another type of event you can check out is known as an App Usage Event, which is used to record a change in app and/or task usage. To see all your app usage events, run:

cf curl /v3/app_usage_events

The BTP Cockpit allows you to see events for your entire space, and also for each individual application.

To see the events for a space, navigate to your space, and there will be a tab on the left labeled Events. Click on this tab, and you will see a list of all events that have occurred in that space. You also have the option of searching and filtering on this list.

To see events for an application in the BTP Cockpit, first navigate to the cf-nodejs app. Once there, you’ll see a tab on the left labeled Events. Click on this, and you will see a list of events that have occurred for that app.

The retention policy for Cloud Foundry events on the SAP BTP is 14 days. As such, if you want to keep track of your events for longer you will need to forward them to another place to be stored. Events are a separate entity from Cloud Foundry logs, and as such they are not stored in the log cache or forwarded in the same way. Therefore, in order to forward events you must use the CF API discussed earlier in this tutorial.

For example, you can get audit events by calling the /v3/audit_events API endpoint, and store the data into a system from your choice. The same can be done for the /v3/app_usage_events endpoint. As mentioned before, you can also fine tune what events you retrieve using the filtering options for each endpoint.

When a Cloud Foundry event occurs, and you want to know about it and be alerted on it, you can use the SAP Alert Notification service for SAP BTP. Using this service with Cloud Foundry you can alert on any of the events discussed in this tutorial, such as when an application crashes because of a failed health check, when an app is getting restarted, and more. This service provides an API for publishing and subscribing to alerts on events, and it also provides real-time notifications for alerts that you have subscribed to. The service also provides several delivery options for alerts and notifications, including e-mail, Slack, and ticket management systems. Check the help page of the service for more information.