Chapter 20. Configuring Layer 3 high availability (HA)

Procedure

1. Log in to the undercloud as the stack user, and source the stackrc file to enable the director command line tools.

   Example

   $ source ~/stackrc

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2. Create a custom YAML environment file.

   Example

   $ vi /home/stack/templates/my-neutron-environment.yaml

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   Tip

   The Orchestration service (heat) uses a set of plans called templates to install and configure your environment. You can customize aspects of the overcloud with a custom environment file, which is a special type of template that provides customization for your heat templates.

3. Set the NeutronL3HA parameter to true in the YAML environment file. This ensures HA is enabled even if director did not set it by default.

   parameter_defaults:
     NeutronL3HA: 'true'

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4. Set the maximum number of L3 agents on which an HA router is scheduled.

   Set the max_l3_agents_per_router parameter to a value between the minimum and total number of network nodes in your deployment. (A zero value indicates that the router is scheduled on every agent.)

   Example

   parameter_defaults:
     NeutronL3HA: 'true'
     ControllerExtraConfig:
       neutron::server::max_l3_agents_per_router: 2

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   In this example, if you deploy four Networking service nodes, only two L3 agents protect each HA virtual router: one active, and one standby.

   If you set the value of max_l3_agents_per_router to be greater than the number of available network nodes, you can scale out the number of standby routers by adding new L3 agents. For every new L3 agent node that you deploy, the Networking service schedules additional standby versions of the virtual routers until the max_l3_agents_per_router limit is reached.

5. Run the openstack overcloud deploy command and include the core heat templates, environment files, and this new custom environment file.

   Important

   The order of the environment files is important because the parameters and resources defined in subsequent environment files take precedence.

   Example

   $ openstack overcloud deploy --templates \
   -e [your-environment-files] \
   -e /usr/share/openstack-tripleo-heat-templates/environments/services/my-neutron-environment.yaml

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   Note

   When NeutronL3HA is set to true, all virtual routers that are created default to HA routers. When you create a router, you can override the HA option by including the --no-ha option in the openstack router create command:

   # openstack router create --no-ha

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