[openstack-dev] [vitrage] [nova] [HA] VM Heartbeat / Healthcheck Monitoring
Greg.Waines at windriver.com
Wed May 17 12:06:33 UTC 2017
Yes that’s correct.
VM Heartbeating / Health-check Monitoring would introduce intrusive / white-box type monitoring of VMs / Instances.
I realize this is somewhat in the gray-zone of what a cloud should be monitoring or not,
but I believe it provides an alternative for Applications deployed in VMs that do not have an external monitoring/management entity like a VNF Manager in the MANO architecture.
And even for VMs with VNF Managers, it provides a highly reliable alternate monitoring path that does not rely on Tenant Networking.
You’re correct, that VM HB/HC Monitoring would leverage
that would require the agent to be installed in the images for talking back to the compute host.
( there are other examples of similar approaches in openstack ... the murano-agent for installation, the swift-agent for object store management )
Although here, in the case of VM HB/HC Monitoring, via the QEMU Guest Agent, the messaging path is internal thru a QEMU virtual serial device. i.e. a very simple interface with very few dependencies ... it’s up and available very early in VM lifecycle and virtually always up.
Wrt failure modes / use-cases
· a VM’s response to a Heartbeat Challenge Request can be as simple as just ACK-ing,
this alone allows for detection of:
o a failed or hung QEMU/KVM instance, or
o a failed or hung VM’s OS, or
o a failure of the VM’s OS to schedule the QEMU Guest Agent daemon, or
o a failure of the VM to route basic IO via linux sockets.
· I have had feedback that this is similar to the virtual hardware watchdog of QEMU/KVM ( https://libvirt.org/formatdomain.html#elementsWatchdog )
· However, the VM Heartbeat / Health-check Monitoring
o provides a higher-level (i.e. application-level) heartbeating
§ i.e. if the Heartbeat requests are being answered by the Application running within the VM
o provides more than just heartbeating, as the Application can use it to trigger a variety of audits,
o provides a mechanism for the Application within the VM to report a Health Status / Info back to the Host / Cloud,
o provides notification of the Heartbeat / Health-check status to higher-level cloud entities thru Vitrage
§ e.g. VM-Heartbeat-Monitor - to - Vitrage - (EventAlarm) - Aodh - ... - VNF-Manager
- (StateChange) - Nova - ... - VNF Manager
From: Adam Spiers <aspiers at suse.com>
Reply-To: "openstack-dev at lists.openstack.org" <openstack-dev at lists.openstack.org>
Date: Tuesday, May 16, 2017 at 7:29 PM
To: "openstack-dev at lists.openstack.org" <openstack-dev at lists.openstack.org>
Subject: Re: [openstack-dev] [vitrage] [nova] [HA] VM Heartbeat / Healthcheck Monitoring
Waines, Greg <Greg.Waines at windriver.com<mailto:Greg.Waines at windriver.com>> wrote:
thanks for the pointers Sam.
I took a quick look.
I agree that the VM Heartbeat / Health-check looks like a good fit into Masakari.
Currently your instance monitoring looks like it is strictly black-box type monitoring thru libvirt events.
Is that correct ?
i.e. you do not do any intrusive type monitoring of the instance thru the QUEMU Guest Agent facility
That is correct:
I think this is what VM Heartbeat / Health-check would add to Masaraki.
Let me know if you agree.
OK, so you are looking for something slightly different I guess, based
on this QEMU guest agent?
That would require the agent to be installed in the images, which is
extra work but I imagine quite easily justifiable in some scenarios.
What failure modes do you have in mind for covering with this
approach - things like the guest kernel freezing, for instance?
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