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Routers in Controller HA

There are only a few differences in how routers work in an HA cluster.

Configuration​

Instead of specifying a single controller, you can specify multiple controllers in the router configuration.

ctrl:
  endpoints:
    - tls:192.168.3.100:6262
    - tls:192.168.3.101:6262
    - tls:192.168.3.102:6262

If the controller cluster changes, it will notify routers of the updated controller endpoints.

By default these will be stored in a file named endpoints in the same directory as the router config file.

However, the file can be customized using a config file settings.

ctrl:
  endpoints:
    - tls:192.168.3.100:6262
  endpointsFile: /var/run/ziti/endpoints.yaml

In general, a router should only need one or two controllers to bootstrap itself, and thereafter should be able to keep the endpoints list up to date with help from the controller.

Router Data Model​

In order to enable HA functionality, the router now receives a stripped down version of the controller data model. While required for controller HA, this also enables other optimizations, so use of the router data model is also enabled by default when running in standalone mode.

The router data model can be disabled on the controller using a config setting, but since it is required for HA, that flag will be ignored if the controllers are running in a cluster.

The data model on the router is periodically snapshotted, so it doesn't need to be fully restored from a controller on every restart.

The location and frequency of snapshotting can be configured.

Controller Selection​

When creating circuits, routers will chose the most responsive controller, based on latency. When doing model updates, such as managing terminators, they will try to talk directly to the current cluster leader, since updates have to go through the leader in any case.