Open Stack

On Thu, Aug 21, 2014 at 09:37:57AM +0000, Duan, Li-Gong (Gary at HPServers-Core-OE-PSC) wrote:
>    Hi Folks,
> 
> 
>    For the "ceilometer alarm-threshold-create" cmd, what is the correct
>    format of the webhook URL for alarm action, if I want to trigger a
>    template in Heat to be executed once this alarm is notified? Are there any
>    example of invoking heat template?

Can you explain what you mean by "invoking heat template" in more detail
please?

The URL is expected to be the pre-signed signal URL provided by some heat
resources, e.g the ScalingPolicy resources for AutoScaling.

>    -----------------------------
> 
>    --alarm-action <Webhook URL>
> 
>            URL to invoke when state transitions to alarm. May be used
>    multiple times. Defaults to None.
> 
>    ----------------------------
> 
>    I "google"ed for this, but most are related to Heat autoscaling and the
>    alarm is defined in Heat template directly.

That is the primary use-case, if you want heat to spin up a new stack in
response to an alarm, the best way to do that is probably via
OS::Heat::AutoScalingGroup, which can scale out heat stacks, here's an
example:

https://github.com/openstack/heat-templates/blob/master/hot/autoscaling.yaml#L65

This will scale out the "lb_server.yaml" template each time ceilometer
posts to the pre-signed URL provided by the OS::Heat::ScalingPolicy
resource:

https://github.com/openstack/heat-templates/blob/master/hot/autoscaling.yaml#L118

However if what you actually want is for ceilometer to spin up a stack by
interacting with the heat API directly triggering the stack create, then I
think currently that is not possible, even if you were to create a
pre-signed stack create call for the heat-api-cfn.

This is because ceilometer inserts a pre-determined request body, which
will only work with the handle_signal methods of the resources which expect
to handle alarm signals from ceilometer:

https://github.com/openstack/heat/blob/master/heat/engine/resources/autoscaling.py#L1028

Steve