Thanks Roger and Lusheng for your kind feedbacks.
I'll look through the links that Roger pointed. Since Holmes does not have to
do anything on metric collecting, I think the top priority for our team is to
handle the state of our containers properly after auto scaling.
As you know, we have a virtual F2F event this week. So I'm not sure whether we
have a chance to discuss this. Please do let me know when you are ready to
Thank you very much.
日 期 ：2018年02月03日 05:13
主 题 ：Re: [onap-discuss] [dcae][dcaegen2][holmes] A Question on AutoScailing of
Thanks for the pointers.
The details of the Kubernetes plan for DCAE is still work-in-progress. Here
are some of highlights for service components.
Will support Kubernetes based scaling and resilience mechanism for dockerized
This implies that the container/containers of a service component will be
packaged as pod. The resilience is expected to be provided by Kubernetes
The Kubernetes based scaling support may need additional support from service
component developer. For example, if a service component is stateless, for
which each instance behaves exactly the same as the next, are “scaling-ready”.
Load can be distributed to any instance and the result would be the same.
However, if the service component keeps states, multiple replicas of this
service component may have different local states if not handled carefully.
The actual mechanism to ensure state synchronization is application dependent.
But one typical approach is to push “states” to an external service such as a
DB, or persistent volume, or a distributed kv store, etc, and states are
loaded into individual replica when needed (e.g. startup) so different replicas
get the state view from the same copy.
In terms of multiple replicas subscribing to the same message router topic,
there is a way to distribute the load. That is, each replica uses the same
“groupid” but different “userid”. Message router will consider a message
received by a group when it is received by any user of the group. This way we
can avoid the same message being delivered to multiple replicas.
Our goal is to maintain the interfaces that how a service component interacts
with the rest of DCAE the same, e.g. how your component gets deployed and how
your component receives configuration updates, etc.
How the scaling trigger arrives and the actual scaling (i.e. more replicas) is
handled by external mechanisms. Service components themselves do not need to
worry about that.
We hope to have more details to share the next week, and set up focus meeting
From: Roger Maitland <roger.maitl...@amdocs.com>
Date: Friday, February 2, 2018 at 1:48 PM
To: "fu.guangr...@zte.com.cn" <fu.guangr...@zte.com.cn>, "JI, LUSHENG
Cc: "email@example.com" <firstname.lastname@example.org>,
Subject: RE: [onap-discuss] [dcae][dcaegen2][holmes] A Question on Auto
Scailing of DCAE Microservices
I don’t have an answer in the context of the DCAE controller but OOM/Kubernetes
has facilities to help build a Holmes cluster in the containerized version of
DCAE (which is being worked on). The cluster can be static (which is believe
is what most projects intend for Beijing) or dynamic (the OOM team would love
to work with you on this). Here are some links I hope you find useful:
Here is a sample of how an auto-scaler is configured:
- type: Resource
- type: Resource
The OOM team would be happy to work with you on implementing this.
[mailto:onap-discuss-boun...@lists.onap.org] On Behalf Of
Sent: Friday, February 2, 2018 2:58 AM
Cc: email@example.com; tang.pe...@zte.com.cn
Subject: [onap-discuss] [dcae][dcaegen2][holmes] A Question on Auto Scailing
of DCAE Microservices
The Holmes team is currently working on the auto scaling plans for Holmes. We
need to confirm something with you.
To my understanding, the microservice should only focus on how to maintain and
balance its data flow rather than how the docker containers/vms are scaled by
their controller. As a DCAE application, I think it's DCAE controller's
responsiblity to determine when and how to scale in or scale out Holmes
instances. Is that correct?
If what my understanding is correct, does DCAE have any specific requirements
regarding collecting the status and metrics of its microservices?
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