Events

An Event is a record generated during engine execution. Such an event captures what has happened inside the senlin-engine. The senlin-engine service generates event records when it is performing some actions or checking policies.

An event has a level property which can be interpreted as the severity level value of the event:

  • 10: interpreted as DEBUG level. Events at this level can be ignored safely by users. For developers they may provide some useful information for debugging the code.

  • 20: interpreted as INFO level. Events at this level are mostly about notifying that some operations have been successfully performed.

  • 30: interpreted as WARNING level. Events at this level are used to signal some unhealthy status or anomalies detected by the engine. These events should be monitored and checked when operating a cluster.

  • 40: interpreted as ERROR level. Events at this level signifies some failures in engine operations. These event should be monitored and checked when operating a cluster. Usually some user intervention is expected to recover a cluster from this status.

  • 50: interpreted as CRITICAL level. Events at this level are about serious problems encountered by the engine. The engine service may have run into some bugs. User intervention is required to do a recovery.

Event Dispatcher Configuration

Senlin provides an open architecture for event dispatching. Two of the built-in dispatchers are database and message.

1. The database dispatcher dumps the events into database tables and it is enabled by default.

2. The message dispatcher converts the event objects into versioned event notifications and published on the global message queue. This dispatcher is by default disabled. To enable it, you can add the following line to the [DEFAULT] section of the senlin.conf file and then restart the service engine:

[default]
event_dispatchers = message

Based on your deployment settings, you have to add the following lines to the senlin.conf file as well when using message dispatcher. This lines set messaging as the default driver used by the oslo.messaging package:

[oslo_messaging_notifications]
driver = messaging

With this configuration, the database dispatcher will be disabled, which means you can only access to the events by the message queue.

3. The event_dispatchers field is MultiString, you can enable both the database and message dispatchers if needed by the following configuration:

[default]
event_dispatchers = database
event_dispatchers = message

[oslo_messaging_notifications]
driver = messaging

Note that unprocessed event notifications which are not associated with a TTL (time to live) value by default will remain queued at the message bus, please make sure the Senlin event notifications will be subscribed and processed by some services before enabling the message dispatcher.

By default, we use the senlin exchange which type is TOPIC to route the notifications to queues with different routing_key. The queues name could be versioned_notifications.debug, versioned_notifications.info, versioned_notifications.warn and versioned_notifications.error that depends on the log level you are using in senlin.conf. The corresponding routing_key are the same as the queues’ name.

There are two options to consume the notifications:

  • Consume the notifications from the default queues directlly.

  • Declare your own queues, then bind them to senlin exchange with corresponding routing_key to customize the flow.

Since the event dispatchers are designed as plug-ins, you can develop your own event dispatchers and have senlin engine load them on startup. For more details on developing and plugging in your own event dispatchers, please refer to the Plugin Writer’s Guide document.

The following sections are about examining events when using the database dispatcher which creates database records when events happen.

Listing Events

The following command lists the events by the Senlin engine:

$ openstack cluster event list
+----------+---------------------+---------------+----------+--------------+-----------------------+-----------+-------+------------+
| id       | generated_at        | obj_type      | obj_id   | obj_name     | action                | status    | level | cluster_id |
+----------+---------------------+---------------+----------+--------------+-----------------------+-----------+-------+------------+
| 1f72eb5e | 2015-12-17T15:41:48 | NODE          | 427e64f3 | node-7171... | update                | ACTIVE    | 20    |            |
| 20b8eb9a | 2015-12-17T15:41:49 | NODE          | 6da22a49 | node-7171... | update                | ACTIVE    | 20    |            |
| 23721815 | 2015-12-17T15:42:51 | NODEACTION    | 5e9a9d3d | node_dele... | NODE_DELETE           | START     | 20    |            |
| 54f9eae4 | 2015-12-17T15:41:36 | CLUSTERACTION | 1bffa11d | cluster_c... | CLUSTER_CREATE        | SUCCEEDED | 20    | 9f1883a7   |
| 7e30df62 | 2015-12-17T15:42:51 | CLUSTERACTION | d3cef701 | cluster_d... | CLUSTER_DELETE        | START     | 20    | 9f1883a7   |
| bf51f23c | 2015-12-17T15:41:54 | CLUSTERACTION | d4dbbcea | cluster_s... | CLUSTER_SCALE_OUT     | START     | 20    | 9f1883a7   |
| c58063e9 | 2015-12-17T15:42:51 | NODEACTION    | b2292bb1 | node_dele... | NODE_DELETE           | START     | 20    |            |
| ca7d30c6 | 2015-12-17T15:41:38 | CLUSTERACTION | 0be70b0f | attach_po... | CLUSTER_ATTACH_POLICY | START     | 20    | 9f1883a7   |
| cfe5d0d7 | 2015-12-17T15:42:51 | CLUSTERACTION | 42cf5baa | cluster_d... | CLUSTER_DELETE        | START     | 20    | 9f1883a7   |
| fe2fc810 | 2015-12-17T15:41:49 | CLUSTERACTION | 0be70b0f | attach_po... | CLUSTER_ATTACH_POLICY | SUCCEEDED | 20    | 9f1883a7   |
+----------+---------------------+---------------+----------+--------------+-----------------------+-----------+-------+------------+

The openstack cluster event list command line supports various options when listing the events.

Sorting the List

You can specify the sorting keys and sorting direction when list events, using the option --sort. The --sort option accepts a string of format key1[:dir1],key2[:dir2],key3[:dir3], where the keys used are event properties and the dirs can be one of asc and desc. When omitted, Senlin sorts a given key using asc as the default direction.

For example, the following command sorts the events using the timestamp property in descending order:

$ openstack cluster event list --sort timestamp:desc

When sorting the list of events, you can use one of timestamp, level, otype, oname, user, action and status.

Filtering the List

You can filter the list of events using the --filters`. For example, the following command filters the event list by the otype property:

$ openstack cluster event list --filters otype=NODE

The option --filters accepts a list of key-value pairs separated by semicolon (;), where each pair is expected to be of format key=val. The valid keys for filtering include oname, otype, oid, cluster_id, action, level or any combination of them.

Paginating the Query results

In case you have a huge collection of events (which is highly likely the case), you can limit the number of events returned using the option --limit. For example:

$ openstack cluster event list --limit 10

Another option you can specify is the ID of an event after which you want to see the returned list starts. In other words, you don’t want to see those events with IDs that is or come before the one you specify. You can use the option --marker for this purpose. For example:

$ openstack cluster event list --limit 20 \
    --marker 2959122e-11c7-4e82-b12f-f49dc5dac270

At most 20 action records will be returned in this example and its UUID comes after the one specified from the command line.

Showing Details of an Event

You can use the senlin command line to show the details about an event you are interested in. When specifying the identity of the event, you can use its name, its ID or its “short ID” . Senlin API and engine will verify if the identifier you specified can uniquely identify an event. An error message will be returned if there is no event matching the identifier or if more than one event matching it.

An example is shown below:

$ openstack cluster event show 19ba155a
+---------------+--------------------------------------+
| Field         | Value                                |
+---------------+--------------------------------------+
| action        | NODE_DELETE                          |
| cluster_id    | ce85d842-aa2a-4d83-965c-2cab5133aedc |
| generated_at  | 2015-12-17T15:43:26+00:00            |
| id            | 19ba155a-d327-490f-aa0f-589f67194b2c |
| level         | INFO                                 |
| location      | None                                 |
| name          | None                                 |
| obj_id        | cd9f519a-5589-4cbf-8a74-03b12fd9436c |
| obj_name      | node-ce85d842-003                    |
| obj_type      | NODE                                 |
| project_id    | 42d9e9663331431f97b75e25136307ff     |
| status        | end                                  |
| status_reason | Node deleted successfully.           |
| user_id       | 5e5bf8027826429c96af157f68dc9072     |
+---------------+--------------------------------------+