Working with Receivers

Working with Receivers

Receivers are the event sinks associated to senlin clusters. When certain events (or alarms) are seen by a monitoring software, the software can notify the senlin clusters of those events (or alarms). When senlin receives those notifications, it can automatically trigger some predefined operations with preset parameter values.

Creating a Receiver

To create a receiver, you need to specify the target cluster and the target action to be triggered in future. For example, the following command creates a receiver that will trigger the CLUSTER_SCALE_IN operation on the target cluster:

$ openstack cluster receiver create --cluster mycluster --action CLUSTER_SCALE_IN w_scale_in

The output from the command will be something like this:

$ openstack cluster receiver create --cluster mycluster --action CLUSTER_SCALE_IN w_scale_in
| Field      | Value                                                                   |
| action     | CLUSTER_SCALE_IN                                                        |
| actor      | {                                                                       |
|            |   "trust_id": "1bc958f5780b4ad38fb6583701a9f39b"                        |
|            | }                                                                       |
| channel    | {                                                                       |
|            |   "alarm_url": "http://node1:8778/v1/webhooks/5dacde18-.../trigger?V=1" |
|            | }                                                                       |
| cluster_id | 7fb3d988-3bc1-4539-bd5d-3f72e8d6e0c7                                    |
| created_at | 2016-05-23T01:36:39                                                     |
| domain_id  | None                                                                    |
| id         | 5dacde18-661e-4db4-b7a8-f2a6e3466f98                                    |
| location   | None                                                                    |
| name       | w_scale_in                                                              |
| params     | None                                                                    |
| project_id | eee0b7c083e84501bdd50fb269d2a10e                                        |
| type       | webhook                                                                 |
| updated_at | None                                                                    |
| user_id    | ab79b9647d074e46ac223a8fa297b846                                        |

From the output of the openstack cluster receiver create command, you can see:

  • There is a type property whose value is set to webhook default which is one of the receiver types senlin supports.
  • There is a channel property which contains an alarm_url key. The value of the alarm_url is the endpoint for your to post a request.

Triggering a Receiver with CURL

Once we have a receiver created, you can test it by triggering the specified action using tools like curl.

$ curl -X POST http://node1:8778/v1/webhooks/5dacde18-661e-4db4-b7a8-f2a6e3466f98/trigger?V=1

After a while, you can check that the cluster has been shrunk by 1 node.

For more details about managing receivers, please check the Receivers section in the 3 User References documentation.

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