Hi Eoghan and folks,

I'm thinking of adding an API to create multiple alarms in a batch.

I think adding an API to create multiple alarms is a good option to solve the 
problem that once an *alarm target* (a vm or a new group of vms) is created, 
multiple requests will be fired because multiple alarms are to be created.

In the our current project, this requiement is specially urgent since our alarm 
target is one VM, and 6 alarms are to be created when one VM is created.

What do you guys think?

Best Regards,
Kurt Rao

----- Original -----
发件人: Eoghan Glynn [mailto:egl...@redhat.com] 
发送时间: 2014年12月3日 20:34
收件人: Rao Dingyuan
抄送: openst...@lists.openstack.org
主题: Re: [Openstack] [Ceilometer] looking for alarm best practice - please help

> Hi folks,
> I wonder if anyone could share some best practice regarding to the 
> usage of ceilometer alarm. We are using the alarm 
> evaluation/notification of ceilometer and we don’t feel very well of 
> the way we use it. Below is our
> problem:
> ============================
> Scenario:
> When cpu usage or memory usage above a certain threshold, alerts 
> should be displayed on admin’s web page. There should be a 3 level 
> alerts according to meter value, namely notice, warning, fatal. Notice 
> means the meter value is between 50% ~ 70%, warning means between 70% 
> ~ 85% and fatal means above 85%
> For example:
> * when one vm’s cpu usage is 72%, an alert message should be displayed 
> saying
> “Warning: vm[d9b7018b-06c4-4fba-8221-37f67f6c6b8c] cpu usage is above 70%”.
> * when one vm’s memory usage is 90%, another alert message should be 
> created saying “Fatal: vm[d9b7018b-06c4-4fba-8221-37f67f6c6b8c] memory 
> usage is above 85%”
> Our current Solution:
> We used ceilometer alarm evaluation/notification to implement this. To 
> distinguish which VM and which meter is above what value, we’ve 
> created one alarm for each VM by each condition. So, to monitor 1 VM, 
> 6 alarms will be created because there are 2 meters and for each meter there 
> are 3 levels.
> That means, if there are 100 VMs to be monitored, 600 alarms will be 
> created.
> Problems:
> * The first problem is, when the number of meters increases, the 
> number of alarms will be multiplied. For example, customer may want 
> alerts on disk and network IO rates, and if we do that, there will be 
> 4*3=12 alarms for each VM.
> * The second problem is, when one VM is created, multiple alarms will 
> be created, meaning multiple http requests will be fired. In the case 
> above, 6 HTTP requests will be needed once a VM is created. And this 
> number also increases as the number of meters goes up.

One way of reducing both the number of alarms and the volume of notifications 
would be to group related VMs, if such a concept exists in your use-case.

This is effectively how Heat autoscaling uses ceilometer, alarming on the 
average of some statistic over a set of instances (as opposed to triggering on 
individual instances).

The VMs could be grouped by setting user-metadata of form:

  nova boot ... --meta metering.my_server_group=foobar

Any user-metadata prefixed with 'metering.' will be preserved by ceilometer in 
the resource_metadata.user_metedata stored for each sample, so that it can used 
to select the statistics on which the alarm is based, e.g.

  ceilometer alarm-threshold-create --name cpu_high_foobar \
    --description 'warning: foobar instance group running hot' \
    --meter-name cpu_util --threshold 70.0 \
    --comparison-operator gt --statistic avg \
    --query metadata.user_metedata.my_server_group=foobar

This approach is of course predicated on the there being some natural grouping 
relation between instances in your environment.


> =============================
> Do anyone have any suggestions?
> Best Regards!
> Kurt Rao
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