Updating HA GUEST API OVERVIEW DOCUMENT based on Bertrand Souville's comments.

- adding standard Doctor / Vitrage Fault Mgmt Architecture Diagram, and
- refering to Doctor SB API

-------------

Updating HA GUEST API OVERVIEW Proposal after review with OPNFV DOCTOR Team.

Minutes from meeting, that were addressed as part of this update are below.

- VM Heartbeating & Health Checking
  * libvirt watchdog and its integration / use with OpenStack
     > https://blueprints.launchpad.net/nova/+spec/libvirt-watchdog
     > https://wiki.openstack.org/wiki/LibvirtWatchdog#Notifications
     > Need to review behaviour of this capability as compared to the
       proposed VM Heartbeating/Health-checking
     > i believe there is a bit of overlap
       but believe that VM Heartbeating / Health-checking provides a
       more complete solution
     > i'll update document with a NOTE on comparing the proposal with
       the libvirt watchdog
  * Update the architecture diagram to be consistent with the most current
    DOCTOR Architecture Diagrams
     > e.g. Vitrage & Congress are not necessrily deployed at same time
     > use DOCTOR terminology where applicable, e.g. "inspector modules"
     > OPNFV DOCTOR includes patches/components of AODH, NOVA, NEUTRON
       ... not just Vitrage and Congress, as shown in diagram
       - although also had comment that should remove OPNFV DOCTOR outline
         from diagram as OPNFV DOCTOR is a reuirement specification and
         not an implementation
     > indicate (possibly just in text below diagram) that the "Guest
       Heartbeat / Health-check Server' on Controller Node is possibly not
       required, as the Vitrage data source interface can be remotely
       reached by "Guest Heartbeat / Health-check Compute" on the Compute
       Node
  * In text, provide a little more detail on content of actual messaging
    e.g. PDUs and rough message content
  * OVERALL
     > believe there was a general agreement in the way that VM Heartbeating
       & Health-checking was integrated / inter-worked with OPNFV DOCTOR's
       Vitrage / Congress and overall OPNFV fault reporting architecture
     > key feedback was to understand and highlight the additional value of
       the VM Heartbeating & Health-checking functionality over the existing
       libvirt watchdog integration into OpenStack.

- Server Group Messaging
  * suggestion that Rabbit MQ pub/sub messaging could be an alternative for
    routing of messages
     > this is an implementation detail though
  * general discussions on "HA use cases" for how this messaging could be
    leveraged
     > e.g. split-brain avoidance, faster peer VM state change notifications
  * OVERALL
     > agreement that the Server Group Messaging Architecture did NOT conflict
       with Doctor Architecture
     > need further review with OPNFV MANO Team as to how they would position
       this functionality
       e.g.
           - position it as an alternative for various HA use cases ?
           - versus
           - mandating that this service group messaging be used for specific
             HA user cases

Change-Id: Icd54bbf8889017cfe3f617656ddf483cbb171e63
Signed-off-by: gwaines <greg.waines@windriver.com>

1 files changed, 56 insertions, 35 deletions

diff --git a/docs/development/overview/OPNFV_HA_Guest_APIs-Overview_HLD.rst b/docs/development/overview/OPNFV_HA_Guest_APIs-Overview_HLD.rst
index 0bc0537..7356f4c 100644
--- a/docs/development/overview/OPNFV_HA_Guest_APIs-Overview_HLD.rst
+++ b/docs/development/overview/OPNFV_HA_Guest_APIs-Overview_HLD.rst
@@ -5,16 +5,16 @@ Overview
 :organization: Wind River Systems
 :organization: OPNFV - High Availability
 :status: Draft - PROPOSAL
-:date: March 2017
-:revision: 1.5
+:date: April 2017
+:revision: 1.6
 
-:abstract: This document presents a PROPOSAL for a set of new
-   optional capabilities where the OpenStack Cloud messages
-   into the Guest VMs in order to provide improved Availability
-   of the hosted VMs.  The initial set of new capabilities
-   include: enabling the detection of and recovery from internal
-   VM faults and providing a simple out-of-band messaging service
-   to prevent scenarios such as split brain.
+:abstract: This document describes a set of new optional
+   capabilities where the OpenStack Cloud messages into the Guest
+   VMs in order to provide improved Availability of the hosted VMs.
+   The initial set of new capabilities include: enabling the
+   detection of and recovery from internal VM faults and providing
+   a simple out-of-band messaging service to prevent scenarios such
+   as split brain.
 
 
 .. sectnum::
@@ -26,8 +26,8 @@ Overview
 Introduction
 =====================================================================
 
-   This document provides an overview and rationale for a PROPOSAL
-   of a set of new capabilities where the OpenStack Cloud messages
+   This document provides an overview and rationale for a
+   set of new capabilities where the OpenStack Cloud messages
    into the Guest VMs in order to provide improved Availability
    of the hosted VMs.
 
@@ -49,10 +49,6 @@ Introduction
    with VNFM), specific OPNFV HA Team deliverables, and the use cases
    for how availability of the hosted VM is improved.
 
-   The intent is for the OPNFV HA Team to review the proposals of this
-   document with the related other teams in OPNFV (Doctor and Management
-   & Orchestration (MANO)) and OpenStack (Nova).
-
 
 
 
@@ -92,18 +88,23 @@ VM Heartbeating and Health Checking
 
    Normally OpenStack monitoring of the health of a Guest VM is limited
    to a black-box approach of simply monitoring the presence of the
-   QEMU/KVM PID containing the VM.
-
-   VM Heartbeating and Health Checking provides a heartbeat service to monitor
-   the health of guest application(s) within a VM running under the OpenStack
-   Cloud.  Loss of heartbeat or a failed health check status will result in a
-   fault event being reported to OPNFV's DOCTOR infrastructure for alarm
-   identification, impact analysis and reporting.  This would then enable VNF
-   Managers (VNFMs) listening to OPNFV's DOCTOR External Alarm Reporting through
+   QEMU/KVM PID containing the VM, and/or by enabling libvirt's emulated
+   hardware watchdog.
+
+   VM Heartbeating and Health Checking provides a heartbeat service to enhance
+   the monitoring of the health of guest application(s) within a VM running
+   under the OpenStack Cloud.  Loss of heartbeat or a failed health check status
+   will result in a fault event being reported to OPNFV's DOCTOR infrastructure
+   for alarm identification, impact analysis and reporting.  This would then enable
+   VNF Managers (VNFMs) listening to OPNFV's DOCTOR External Alarm Reporting through
    Telemetry's AODH, to initiate any required fault recovery actions.
 
    .. image:: OPNFV_HA_Guest_APIs-Overview_HLD-Guest_Heartbeat-FIGURE-1.png
 
+   Or, in the context of the OPNFV DOCTOR's Fault Management Architecture:
+
+   .. image:: OPNFV_HA_Guest_APIs-Overview_HLD-Guest_Heartbeat-FIGURE-1b.png
+
    The VM Heartbeating and Health Checking functionality is enabled on
    a VM through a new flavor extraspec indicating that the VM supports
    and wants to enable Guest Heartbeating.  An extension to Nova Compute uses
@@ -115,8 +116,8 @@ VM Heartbeating and Health Checking
    (i.e. the Guest VM).  The OpenStack Compute Node will start heartbeating the
    Guest VM, and if the heartbeat fails, the OpenStack Compute Node will report
    the VM Fault thru DOCTOR and ultimately VNFM will see this thru NOVA VM
-   State Chagne Notifications thru AODH.  I.e. VNFM wouild see the VM Heartbeat
-   Failure events in teh same way it sees all other VM Faults, thru DOCTOR
+   State Change Notifications thru AODH.  I.e. VNFM wouild see the VM Heartbeat
+   Failure events in the same way it sees all other VM Faults, thru DOCTOR
    initiated VM state changes.
 
    Part of the Guest VM's registration process is the specification of the
@@ -130,8 +131,13 @@ VM Heartbeating and Health Checking
    If the OpenStack Host does not receive a valid response, or if the response
    specifies that the VM is in ill health, then a fault event for the Guest VM
    is reported to the OpenStack Guest Heartbeat Service on the controller node which
-   will report the event to OPNFV's DOCTOR (i.e. thru the OpenStack Vitrage data
-   source APIs).
+   will report the event to OPNFV's DOCTOR (i.e. thru the Doctor SouthBound (SB)
+   APIs).
+
+   In summary, the Guest Heartbeating Messaging Specification is quite simple,
+   including the following PDUs: Init, Init-Ack, Challenge-Request,
+   Challenge-Response, Exit.  The Challenge-Response returning a healthy /
+   not-healthy boolean.
 
    The registered Guest VM daemon's response to the challenge can be as simple
    as just immediately responding with OK.  This alone allows for detection of
@@ -177,8 +183,19 @@ VM Heartbeating and Health Checking
       - will provide code and compile instructions,
       - Guest will compile based on its specific OS.
 
-   This proposal requires review with OPNFV's Doctor and Management & Orchestration
-   teams, and OpenStack's Nova Team.
+   NOTE that the described VM Heartbeating and Healthchecking functionality provides
+   enhanced monitoring over and above libvirt's emulated hardware watchdog.  VM
+   Heartbeating and Healthchecking can detect a wider range of issues than simply
+   lack of cpu time scheduling for a lower priority process feeding the hardware
+   watchdog.  VM Heartbeating and Healthchecking can ensure that specific key processes
+   within the application are not blocked, kernel resources for basic IO within
+   the Guest VM are available, and/or ensure the application-specific health of the VM
+   is good.
+
+   This proposal has been reviewed with both the OPNFV's Doctor and Management
+   and Orchestration teams, and general agreement was that the proposal integrated
+   / inter-worked correctly with the OPNFV DOCTOR's Vitrage, Congress and the overall
+   OPNFV fault reporting architecture.
 
 
 
@@ -257,19 +274,23 @@ VM Peer State Notification and Messaging
      Server Group Messaging containing the peer protocol layers
      and Guest Application hooks within the Guest.
 
-   This proposal requires review with OPNFV's Management & Orchestration team and
-   OpenStack's Nova Team.
+   This proposal has been reviewed with both the OPNFV's Doctor and Management
+   and Orchestration teams, and general agreement was that the proposal did not
+   conflict with the OPNFV Doctor Architecture, and provided, at the very least,
+   an alternative messaging and state-change-notification mechanism for hosted
+   VMs in various HA use cases.
+
 
 
 Conclusion
 ======================================================================================
 
-   The PROPOSAL of Reach-thru Guest Monitoring and Services described in this document
+   The Reach-thru Guest Monitoring and Services described in this document
    leverage Host-to-Guest messaging to provide a number of extended capabilities
    that improve the Availability of the hosted VMs.  These new capabilities
    enable detection of and recovery from internal VM faults and provides a simple
    out-of-band messaging service to prevent scenarios such as split brain.
 
-   The integration of these proposed new capabilities into the larger OpenStack and OPNFV
-   Architectures need to be reviewed with the other related teams in OPNFV (Doctor and
-   Management & Orchestration (MANO)) and OpenStack (Nova).
+   The next steps in progressing this proposal will be to submit blueprints to
+   the appropriate OpenStack working groups;  Vitrage for VM Heartbeating and
+   Healthchecking and Nova for VM Server Group Messaging.