Carrier is a Kubernetes controller for running and scaling game servers on Kubernetes.
This project is inspired by agones.
Generally speaking, the online multiplayer games such as competitive FPSs and MOBAs, require a Dedicated Game Server(DS) which simulating game worlds, and players connect to the server with separate client programs, then playing within it.
Dedicated game servers are stateful applications that retain the full game simulation in memory. But unlike other stateful applications, such as databases, they have a short lifetime. Rather than running for months or years, a dedicated game server process will exit when a game is over, which usually lasts a few minutes or hours.
The Kubernetes Statefulset workload does not manage such applications well. Carrier communicates with the game server through the SDK, and dedicated server can notify the Carrier when no player whthin it, then the Carrier can delete the Pod safely. Conversely, when scaling down the Kubernetes cluster, Carrier can also notify the game server through the SDK, which allows the Carrier to better running and scaling the game server.
Carrier provides many extensions to communicate with game server and services out of K8s clusters.
-
SDK
communicate with game server directly, which enables game server runtime fetching the
GameServerstatus running in K8s, e.g. LB Status, Labels and Annotations. -
Webhook(Readiness/Deletable)
this extension helps user to define when a
GameServeris ready or can be deleted. Carrier will fetch theGameServerstatus from webhook servers developed by users according to the protocol.
There are many players on different GameServer. Since carrier do not allow scaling down a GameServer when it is not deletable, carrier should scale down
the GameServers in order to avoid waiting long time. An annotation named carrier.ocgi.dev/gs-deletion-cost is used for helping sort the GameServers. This
annotation can be added by SDK or set carrier.ocgi.dev/gs-cost-metrics-name to enable fetching metrics to set carrier.ocgi.dev/gs-deletion-cost.
We support some policies to Update Squad.
- Recreate
- RollingUpdate
- CanaryUpdate
- InPlaceUpdate
Here’s an example of dedicated game server architecture based on Carrier.
-
MatchMaker Responsible for match making (developed by the application)
-
Dscenter Responsible for
Dedicated Servermanagement and allocation (developed by the application) -
Dedicated Server Corresponds to a
GameServer, manages multiple DS processes, and reports ds information toDscenter.Dedicated ServerandCarrier-SDKas a whole are deployed in the same K8s Pod -
Carrier Controller Manage a group of
GameServers(include create, update, delete) and maintain a certain number of replicas of the DS cluster -
Autoscaler Calculate and adjust the number of replicas of the DS cluster according to application metrics, events, time, etc.
Build and deploy the Carrier.
# make container# # change the image version if you would like to deploy a specified version(default: latest).
# kubectl apply -f manifeasts/crd.yaml
# kubectl apply -f manifeasts/deploy.yamlYou can view the full documentation from the website.
Carrier is licensed under the Apache License, Version 2.0. See LICENSE for the full license text.