OVSvApp monitoring changes to support fault tolerance

[Romil Gupta]

With the introduction of OVSvApp solution, which consists of
a service VM hosted on ESX hosts within a data center.

To address the Fault Tolerance and High Availablity of OVSvApp.

OVSvApp solution caters to the following failure scenarios:

OVSvApp agent crash:
  - upstart mechanism tries to bring up the agent back.

Open vSwitch process crash:
  - Child process of OVSvApp agent will monitor the OpenvSwitch
    and tries to restart it when crashed.
  - This will help us to re-populate the flows at the earliest
     to resume the tenant VM data network connectivity.

OVSvApp VM crash:
  - Agent monitoring mechanism will put ESX host in maintenance mode
    or powers off as per "esx_maintenance_mode" param configuration.
    By default, 'esx_maintenance_mode' is True, so we put the host to
    maintenance mode.
  - vCenter DRS will migrate tenant VMs to other ESX hosts within the
    cluster and safeguards traffic from being blackholed.
  - Agent monitoring can be turned on/off using the configuration
    "enable_agent_monitor" flag configuration in neutron configuration.
    By default, it is enabled.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/213124
Committed: https://git.openstack.org/cgit/openstack/networking-vsphere/commit/?id=f3072cdaf71b2ca52a3825d9f58aca1f2df9aa4a
Submitter: Jenkins
Branch: master

commit f3072cdaf71b2ca52a3825d9f58aca1f2df9aa4a
Author: Romil Gupta <email address hidden>
Date: Fri Aug 14 05:33:58 2015 -0700

    Fix ovsvapp_monitor.py

    Updated the ovsvapp_monitor.py to read a correct
    configuration from an agent.

    Partial-bug: #1485433

    Change-Id: I2d5a1f619cf89d6dc660ff52768e4aaa3108c1c2

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/211930
Committed: https://git.openstack.org/cgit/openstack/networking-vsphere/commit/?id=99b612f915f3b18b3c80b4c31e331e7c5ef3bcc8
Submitter: Jenkins
Branch: master

commit 99b612f915f3b18b3c80b4c31e331e7c5ef3bcc8
Author: Romil Gupta <email address hidden>
Date: Wed Aug 12 02:38:07 2015 -0700

    Follow up changes for OVSvApp Agent monitoring

    Closes-Bug: #1485433

    Co-Authored-By: Sudhakar Babu Gariganti <email address hidden>

    Change-Id: I95389b5c5d2f54b16b81cb50aee1040e8299e95e