How to trigger Qinling function in Aodh¶
Aodh is the Alarming service project in OpenStack that enables the ability to trigger actions based on defined rules against metric or event data collected by Ceilometer or Gnocchi.
We can use Aodh alarm to trigger Qinling functions by some cloud events, e.g. when an instance is created in this guide.
Step1: Create webhook for the function in Qinling¶
Webhook in Qinling allows to trigger the function without providing OpenStack credentials, the webhook URL is only known by the function owner.
Suppose we have a simple Python function that prints out a string:
$ cat ~/functions/hello_world.py
def main(name='World', **kwargs):
ret = 'Hello, %s' % name
return ret
Create a function using the Python script:
$ RUNTIME_ID=bd516a15-3787-4652-938b-e25665c376e6
$ openstack function create --runtime $RUNTIME_ID \
--entry hello_world.main \
--file ~/functions/hello_world.py
+-------------+-------------------------------------------------------------------------+
| Field | Value |
+-------------+-------------------------------------------------------------------------+
| id | 5b25e0ea-7f8d-487a-bce6-f6a2556a1e3f |
| name | None |
| description | None |
| count | 0 |
| code | {u'source': u'package', u'md5sum': u'9bad2959cafc9d89684fe7a336de9927'} |
| runtime_id | bd516a15-3787-4652-938b-e25665c376e6 |
| entry | hello_world.main |
| project_id | 360d69d06890407eab1a44573c1f3776 |
| created_at | 2018-05-13 06:58:13.208421 |
| updated_at | None |
+-------------+-------------------------------------------------------------------------+
Create a webhook for the function:
$ function_id=5b25e0ea-7f8d-487a-bce6-f6a2556a1e3f
$ openstack webhook create $function_id
+-------------+-------------------------------------------------------------------------------+
| Field | Value |
+-------------+-------------------------------------------------------------------------------+
| id | a5f82898-a4c3-4104-ad2d-40fbafbe8857 |
| function_id | 5b25e0ea-7f8d-487a-bce6-f6a2556a1e3f |
| description | None |
| project_id | 360d69d06890407eab1a44573c1f3776 |
| created_at | 2018-05-13 06:59:20.616092 |
| updated_at | None |
| webhook_url | http://10.0.0.14:7070/v1/webhooks/a5f82898-a4c3-4104-ad2d-40fbafbe8857/invoke |
+-------------+-------------------------------------------------------------------------------+
The webhook_url could be used to trigger the function without any
authentication. Make note of this URL, as it will be used as the alarm action
when we create the alarm in Aodh.
Step2: Create an event alarm in Aodh¶
In Aodh, we only need to define an alarm that will be triggered by the event
compute.instance.create (Nova will emit the event when there is a new VM
created), using the webhook URL from Step1.
$ webhook_url=http://10.0.0.14:7070/v1/webhooks/a5f82898-a4c3-4104-ad2d-40fbafbe8857/invoke
$ aodh alarm create --name qinling-alarm \
--type event --alarm-action $webhook_url \
--repeat-actions false --event-type compute.instance.create
+---------------------------+------------------------------------------------------------------------------------+
| Field | Value |
+---------------------------+------------------------------------------------------------------------------------+
| alarm_actions | [u'http://10.0.0.14:7070/v1/webhooks/a5f82898-a4c3-4104-ad2d-40fbafbe8857/invoke'] |
| alarm_id | 1f85edea-a8a6-47ba-b1f5-9e3ac7ee61dc |
| description | Alarm when compute.instance.create event occurred. |
| enabled | True |
| event_type | compute.instance.create |
| insufficient_data_actions | [] |
| name | qinling-alarm |
| ok_actions | [] |
| project_id | 360d69d06890407eab1a44573c1f3776 |
| query | |
| repeat_actions | False |
| severity | low |
| state | insufficient data |
| state_reason | Not evaluated yet |
| state_timestamp | 2018-05-13T07:13:03.631059 |
| time_constraints | [] |
| timestamp | 2018-05-13T07:13:03.631059 |
| type | event |
| user_id | 26d9ec1da7fc4756b1940e69292565c2 |
+---------------------------+------------------------------------------------------------------------------------+
Step3: Simulate an event trigger¶
For testing purpose, I wrote a Python script to generate an event for this Aodh
alarm so that we don’t need to install and config Nova and Ceilometer service.
The script sends a notification with event_type as
compute.instance.create to Aodh service directly. The script was tested
in a default Devstack environment.
First, create a config file for the script:
$ mkdir -p /etc/lingxian
$ cat <<EOF > /etc/lingxian/lingxian.conf
[oslo_messaging_rabbit]
rabbit_userid = stackrabbit
rabbit_password = password
EOF
Download the script, modify the conf_file and project_id, the
project_id should be the same with the project who created the alarm. Run
the script:
$ curl -sSO https://raw.githubusercontent.com/lingxiankong/qinling_utils/master/aodh_notifier_simulator.py
$ python aodh_notifier_simulator.py
Now the alarm should be triggered, and the webhook is invoked. Check the alarm history, we could see the alarm state transition:
$ alarm_id=1f85edea-a8a6-47ba-b1f5-9e3ac7ee61dc
$ aodh alarm-history show $alarm_id -f yaml
- detail: '{"transition_reason": "Event <id=ac6ce4ae-546a-47cc-a0cb-ad1bae44ca61,event_type=compute.instance.create>
hits the query <query=[]>.", "state": "alarm"}'
event_id: 3250eed6-edaf-41e8-bfa6-42b060f96e75
timestamp: '2018-05-13T08:34:47.977951'
type: state transition
- detail: '{"state_reason": "Not evaluated yet", "user_id": "26d9ec1da7fc4756b1940e69292565c2",
"name": "qinling-alarm", "state": "insufficient data", "timestamp": "2018-05-13T07:13:03.631059",
"description": "Alarm when compute.instance.create event occurred.", "enabled":
true, "state_timestamp": "2018-05-13T07:13:03.631059", "rule": {"query": [], "event_type":
"compute.instance.create"}, "alarm_id": "1f85edea-a8a6-47ba-b1f5-9e3ac7ee61dc",
"time_constraints": [], "insufficient_data_actions": [], "repeat_actions": false,
"ok_actions": [], "project_id": "360d69d06890407eab1a44573c1f3776", "type": "event",
"alarm_actions": ["http://10.0.0.14:7070/v1/webhooks/a5f82898-a4c3-4104-ad2d-40fbafbe8857/invoke"],
"severity": "low"}'
event_id: 231ca53e-5d74-4191-8136-b332d2d91f1a
timestamp: '2018-05-13T07:13:03.631059'
type: creation
Check the function execution in Qinling:
$ function_id=5b25e0ea-7f8d-487a-bce6-f6a2556a1e3f
$ openstack function execution list --filter function_id=$function_id -f yaml
- Created_at: '2018-05-13 08:34:49'
Description: Created by Webhook a5f82898-a4c3-4104-ad2d-40fbafbe8857
Function_id: 5b25e0ea-7f8d-487a-bce6-f6a2556a1e3f
Id: 41b351fa-a96b-4d86-ba77-33f7bca3dad1
Input: '{"current": "alarm", "alarm_id": "1f85edea-a8a6-47ba-b1f5-9e3ac7ee61dc",
"reason": "Event <id=ac6ce4ae-546a-47cc-a0cb-ad1bae44ca61,event_type=compute.instance.create>
hits the query <query=[]>.", "severity": "low", "reason_data": {"type": "event",
"event": {"event_type": "compute.instance.create", "traits": [["project_id", 1,
"360d69d06890407eab1a44573c1f3776"], ["service", 1, "nova"], ["vm_name", 1, "new_instance"],
["vm_id", 1, "ba2b30a0-1b14-4ad4-9a66-f24ece912cad"]], "message_signature": "bcfb59e386d5375dbb7ded9910900a98536f168d377f52ae7ffd89159c0019f5",
"raw": {}, "generated": "2017-10-03T10:02:38.305378", "message_id": "ac6ce4ae-546a-47cc-a0cb-ad1bae44ca61"}},
"alarm_name": "qinling-alarm", "previous": "insufficient data"}'
Project_id: 360d69d06890407eab1a44573c1f3776
Result: '{"duration": 0.084, "output": "Hello, World"}'
Status: success
Sync: false
Updated_at: '2018-05-13 08:34:53'
Conclusion¶
Although a Qinling function can be invoked on demand, trigger the function according to the cloud events automatically(i.e. event-driven) can bring more power to your function and make your whole application more efficient and cost effective.
