High Availability Agones
Warning
The split controller and extensions feature is currently Alpha, not enabled by default, and may change in the future.
Use the FeatureGate SplitControllerAndExtensions
to enable and test this feature.
See the Feature Gate documentation for details on how to enable features.
High Availability for Agones Controller
When SplitControllerAndExtensions
is enabled, the agones-controller
responsibility is split up into agones-controller
, which enacts the Agones control loop, and agones-extensions
, which acts as a service endpoint for webhooks and the allocation extension API. Splitting these responsibilities allows the agones-extensions
pod to be horizontally scaled, making the Agones control plane highly available and more resiliant to disruption.
GKE Autopilot Clusters
SplitControllerAndExtensions
must be enabled for GKE Autopilot.
Extension Pod Configrations
The agones-extensions
binary has a similar helm
configuration to agones-controller
, see here. If you previously overrode agones.controller.*
settings, you may need to override the same agones.extensions.*
setting.
To change controller.numWorkers
to 200 from 100 values and through the use of helm --set
, add the follow to the helm
command:
extensions
values!
...
--set agones.controller.numWorkers=200
...
An important configuration to note is the PodDisruptionBudget fields, agones.extensions.pdb.minAvailable
and agones.extensions.pdb.maxUnavailable
. Currently, the agones.extensions.pdb.minAvailable
field is set to 1.
Deployment Considerations
When SplitControllerAndExtensions
is enabled, what was previously a single agones-controller
pod is deployed as agones-controller
and 2 agones-extensions
pods. For example:
NAME READY STATUS RESTARTS AGE
agones-allocator-78c6b8c79-h9nqc 1/1 Running 0 23h
agones-allocator-78c6b8c79-l2bzp 1/1 Running 0 23h
agones-allocator-78c6b8c79-rw75j 1/1 Running 0 23h
agones-controller-fbf944f4-vs9xx 1/1 Running 0 23h
agones-extensions-5648fc7dcf-hm6lk 1/1 Running 0 23h
agones-extensions-5648fc7dcf-qbc6h 1/1 Running 0 23h
agones-ping-5b9647874-2rrl6 1/1 Running 0 27h
agones-ping-5b9647874-rksgg 1/1 Running 0 27h
The number of replicas for agones-extensions
can be set using helm variable agones.extensions.replicas
, but the default is 2
.
We expect the aggregate memory consumption of the pods will be slightly higher than the previous singleton pod, but as the responsibilities are now split across the pods, the aggregate CPU consumption should also be similar.
Feature Design
SplitControllerAndExtensions
represents phase 1 of HA Agones. The remaining phases are not yet implemented.
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Last modified March 29, 2023: Helm test content update in Agones doc (#3052) (60f72f0)