Gambia Release Doc

Add HA analysis doc for Gambia Release

JIRA: HA-32

Change-Id: I67a9e8b62b509b9d0b70bbe5613a90e3e7a18b9e
Signed-off-by: fuqiao@chinamobile.com

1 files changed, 0 insertions, 289 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
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-Overview
-=====================================================================
-
-: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::
-
-.. contents:: Table of Contents
-
-
-
-Introduction
-=====================================================================
-
-   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.
-
-   The initial set of new capabilities specifically include:
-
-        - VM Heartbeating and Health Checking
-        - VM Peer State Notification and Messaging
-
-   All of these capabilities leverage Host-to-Guest Messaging
-   Interfaces / APIs which are built on a messaging service between the
-   OpenStack Host and the Guest VM that uses a simple low-bandwidth
-   datagram messaging capability in the hypervisor and therefore has no
-   requirements on OpenStack Networking, and is available very early
-   after spawning the VM.
-
-   For each capability, the document outlines the interaction with
-   the Guest VM, any key technologies involved, the integration into
-   the larger OpenStack and OPNFV Architectures (e.g. interactions
-   with VNFM), specific OPNFV HA Team deliverables, and the use cases
-   for how availability of the hosted VM is improved.
-
-
-
-
-Messaging Layer
-========================================================================
-
-   The Host-to-Guest messaging APIs used by the services discussed
-   in this document use a JSON-formatted application messaging layer
-   on top of a ‘virtio serial device�between QEMU on the OpenStack Host
-   and the Guest VM.  JSON formatting provides a simple, humanly readable
-   messaging format which can be easily parsed and formatted using any
-   high level programming language being used in the Guest VM (e.g. C/C++,
-   Python, Java, etc.).  Use of the ‘virtio serial device�provides a
-   simple, direct communication channel between host and guest which is
-   independent of the Guest’s L2/L3 networking.
-
-   The upper layer JSON messaging format is actually structured as a
-   hierarchical JSON format containing a Base JSON Message Layer and an
-   Application JSON Message Layer:
-
-        - the Base Layer provides the ability to multiplex different groups
-          of message types on top of a single ‘virtio serial device�
-          e.g.
-
-           + heartbeating and healthchecks,
-           + server group messaging,
-
-          and
-
-        - the Application Layer provides the specific message types and
-          fields of a particular group of message types.
-
-
-
-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, 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
-   this extraspec to setup the required 'virtio serial device' for Host-to-Guest
-   messaging, on the QEMU/KVM instance created for the VM.
-
-   A daemon within the Guest VM will register with the OpenStack Guest
-   Heartbeat Service on the compute node to initiate the heartbeating on itself
-   (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 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
-   heartbeat interval in msecs.  I.e. the registering Guest VM specifies the
-   heartbeating interval.
-
-   Guest heartbeat works on a challenge response model.  The OpenStack
-   Guest Heartbeat Service on the compute node will challenge the registered
-   Guest VM daemon with a message each interval.  The registered Guest VM daemon
-   must respond prior to the next interval with a message indicating good health.
-   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 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
-   a failed or hung QEMU/KVM instance, or a failure of the OS within the VM to
-   schedule the registered Guest VM's daemon or failure to route basic IO within
-   the Guest VM.
-
-   However the registered Guest VM daemon's response to the challenge can be more
-   complex, running anything from a quick simple sanity check of the health of
-   applications running in the Guest VM, to a more thorough audit of the
-   application state and data.  In either case returning the status of the
-   health check enables the OpenStack host to detect and report the event in order
-   to initiate recovery from application level errors or failures within the Guest VM.
-
-   In summary, the deliverables of this activity would be:
-
-   - Host Deliverables:    (OpenStack and OPNFV blueprints and implementation)
-
-   + an OpenStack Nova or libvirt extension to interpret the new flavor extraspec and
-     if present setup the required 'virtio serial device' for Host-to-Guest
-     heartbeat / health-check messaging, on the QEMU/KVM instance created
-     for the VM,
-   + an OPNFV Base Host-to-Guest Msging Layer Agent for multiplexing of Application
-     Layer messaging over the 'virtio serial device' to the VM,
-   + an OPNFV Heartbeat / Health-Check Compute Agent for local heartbeating of VM
-     and reporting of failures to the OpenStack Controller,
-   + an OPNFV Heartbeat / Health-check Server on the OpenStack Controller for
-     receiving VM failure notifications and reporting these to Vitrage thru
-     Vitrage's Data Source API,
-
-   - Guest Deliverables:
-
-   + a Heartbeat / Health-Check Message Specification covering
-
-      - Heartbeat / Health-Check Application Layer JSON Protocol,
-      - Base Host-to-Guest JSON Protocol,
-      - Details on the use of the underlying 'virtio serial device',
-
-   + a Reference Implementation of the Guest-side support of
-     Heartbeat / Health-check containing the peer protocol layers
-     within the Guest.
-
-      - will provide code and compile instructions,
-      - Guest will compile based on its specific OS.
-
-   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.
-
-
-
-VM Peer State Notification and Messaging
-===================================================================================
-
-   Server Group State Notification and Messaging is a service to provide
-   simple low-bandwidth datagram messaging and notifications for servers that
-   are part of the same server group.  This messaging channel is available
-   regardless of whether IP networking is functional within the server, and
-   it requires no knowledge within the server about the other members of the group.
-
-   NOTE: A Server Group here is the OpenStack Nova Server Group concept where VMs
-   are grouped together for purposes of scheduling.  E.g. A specific Server Group
-   instance can specify whether the VMs within the group should be scheduled to
-   run on the same compute host or different compute hosts.  A 'peer' VM in the
-   context of this section refers to a VM within the same Nova Server Group.
-
-   This Server Group Messaging service provides three types of messaging:
-
-        - Broadcast: this allows a server to send a datagram (size of up to 3050 bytes)
-          to all other servers within the server group.
-        - Notification: this provides servers with information about changes to the
-          (Nova) state of other servers within the server group.
-        - Status: this allows a server to query the current (Nova) state of all servers within
-          the server group (including itself).
-
-   A Server Group Messaging entity on both the controller node and the compute nodes
-   manage the routing of of VM-to-VM messages through the platform, leveraging Nova
-   to determine Server Group membership and compute node locations of VMs.  The Server
-   Group Messaging entity on the controller also listens to Nova VM state change notifications
-   and querys VM state data from Nova, in order to provide the VM query and notification
-   functionality of this service.
-
-   .. image:: OPNFV_HA_Guest_APIs-Overview_HLD-Peer_Messaging-FIGURE-2.png
-
-   This service is not intended for high bandwidth or low-latency operations.  It
-   is best-effort, not reliable.  Applications should do end-to-end acks and
-   retries if they care about reliability.
-
-   This service provides building block type capabilities for the Guest VMs that
-   contribute to higher availability of the VMs in the Guest VM Server Group.  Notifications
-   of VM Status changes potentially provide a faster and more accurate notification
-   of failed peer VMs than traditional peer VM monitoring over Tenant Networks.  While
-   the Broadcast Messaging mechanism provides an out-of-band messaging mechanism to
-   monitor and control a peer VM under fault conditions; e.g. providing the ability to
-   avoid potential split brain scenarios between 1:1 VMs when faults in Tenant
-   Networking occur.
-
-   In summary, the deliverables for Server Group Messaging would be:
-
-   - Host Deliverables:
-
-   + a Nova or libvirt extension to interpret the new flavor extraspec and
-     if present setup the required 'virtio serial device' for Host-to-Guest
-     Server Group Messaging, on the QEMU/KVM instance created
-     for the VM,
-   + [ leveraging the Base Host-to-Guest Msging Layer Agent from previous section ],
-   + a Server Group Messaging Compute Agent for implementing the Application Layer
-     Server Group Messaging JSON Protocol with the VM, and forwarding the
-     messages to/from the Server Group Messaging Server on the Controller,
-   + a Server Group Messaging Server on the Controller for routing broadcast
-     messages to the proper Computes and VMs, as well as listening for Nova
-     VM State Change Notifications and forwarding these to applicable Computes
-     and VMs,
-
-   - Guest Deliverables:
-
-   + a Server Group Messaging Message Specification covering
-
-      - Server Group Messaging Application Layer JSON Protocol,
-      - [ leveraging Base Host-to-Guest JSON Protocol from previous section ],
-      - [ leveraging Details on the use of the underlying 'virtio serial device' from previous section ],
-
-   + a Reference Implementation of the Guest-side support of
-     Server Group Messaging containing the peer protocol layers
-     and Guest Application hooks within the Guest.
-
-   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 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 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.