8.0 KiB
OpenKruiseGame的伸缩特性
缩容顺序
OKG提供游戏服状态设置的能力，您可以手动/自动(服务质量功能)地设置游戏服的运维状态或删除优先级。当缩容时，GameServerSet负载会根据游戏服的状态进行缩容选择，缩容规则如下：
1）根据游戏服的opsState缩容。按顺序依次缩容opsState为WaitToBeDeleted、None、Allocated、Maintaining的游戏服
2）当opsState相同时，按照DeletionPriority(删除优先级)缩容，优先删除DeletionPriority大的游戏服
3）当opsState与DeletionPriority都相同时，优先删除名称尾部序号较大的游戏服
示例
部署一个副本为5的游戏服：
cat <<EOF | kubectl apply -f -
apiVersion: game.kruise.io/v1alpha1
kind: GameServerSet
metadata:
name: minecraft
namespace: default
spec:
replicas: 5
updateStrategy:
rollingUpdate:
podUpdatePolicy: InPlaceIfPossible
gameServerTemplate:
spec:
containers:
- image: registry.cn-hangzhou.aliyuncs.com/acs/minecraft-demo:1.12.2
name: minecraft
EOF
生成5个GameServer：
kubectl get gs
NAME STATE OPSSTATE DP UP
minecraft-0 Ready None 0 0
minecraft-1 Ready None 0 0
minecraft-2 Ready None 0 0
minecraft-3 Ready None 0 0
minecraft-4 Ready None 0 0
对minecraft-2设置删除优先级为10：
kubectl edit gs minecraft-2
...
spec:
deletionPriority: 10 #初始为0，调大到10
opsState: None
updatePriority: 0
...
手动缩容到4个副本：
kubectl scale gss minecraft --replicas=4
gameserverset.game.kruise.io/minecraft scale
游戏服的数目最终变为4，可以看到2号游戏服因为删除优先级最大所以被删除：
kubectl get gs
NAME STATE OPSSTATE DP UP
minecraft-0 Ready None 0 0
minecraft-1 Ready None 0 0
minecraft-2 Deleting None 10 0
minecraft-3 Ready None 0 0
minecraft-4 Ready None 0 0
# After a while
...
kubectl get gs
NAME STATE OPSSTATE DP UP
minecraft-0 Ready None 0 0
minecraft-1 Ready None 0 0
minecraft-3 Ready None 0 0
minecraft-4 Ready None 0 0
设置minecraft-3的opsState为WaitToBeDeleted：
kubectl edit gs minecraft-3
...
spec:
deletionPriority: 0
opsState: WaitToBeDeleted #初始为None, 将其改为WaitToBeDeleted
updatePriority: 0
...
手动缩容到3个副本：
kubectl scale gss minecraft --replicas=3
gameserverset.game.kruise.io/minecraft scaled
游戏服的数目最终变为3，可以看到3号游戏服因为处于WaitToBeDeleted状态所以被删除：
kubectl get gs
NAME STATE OPSSTATE DP UP
minecraft-0 Ready None 0 0
minecraft-1 Ready None 0 0
minecraft-3 Deleting WaitToBeDeleted 0 0
minecraft-4 Ready None 0 0
# After a while
...
kubectl get gs
NAME STATE OPSSTATE DP UP
minecraft-0 Ready None 0 0
minecraft-1 Ready None 0 0
minecraft-4 Ready None 0 0
手动扩容回5个副本：
kubectl scale gss minecraft --replicas=5
gameserverset.game.kruise.io/minecraft scaled
游戏服的数目最终变为5，此时扩容出的游戏服序号为2与3：
kubectl get gs
NAME STATE OPSSTATE DP UP
minecraft-0 Ready None 0 0
minecraft-1 Ready None 0 0
minecraft-2 Ready None 0 0
minecraft-3 Ready None 0 0
minecraft-4 Ready None 0 0
游戏服 ID Reserve
GameServerSet提供了Spec.ReserveGameServerIds字段。通过该字段，用户指定ID，将对应的游戏服删除；或者在创建新游戏服时避免该序号对应的游戏服生成。
例如，gss下存在5个游戏服，ID分别为0、1、2、3、4。此时设置ReserveGameServerIds，填写3和4，在不更改副本数目的情况下，gss将会删除3和4，同时生成5和6的游戏服，如下所示：
kubectl edit gss minecraft
...
spec:
reserveGameServerIds:
- 3
- 4
...
# After a while
kubectl get gs
NAME STATE OPSSTATE DP UP AGE
minecraft-0 Ready None 0 0 79s
minecraft-1 Ready None 0 0 79s
minecraft-2 Ready None 0 0 79s
minecraft-3 Deleting None 0 0 78s
minecraft-4 Deleting None 0 0 78s
minecraft-5 Ready None 0 0 23s
minecraft-6 Ready None 0 0 23s
如若填写在ReserveGameServerIds字段增加5和6，同时减少副本数目到3，则gss会删除5和6的游戏服，如下所示：
kubectl edit gss minecraft
...
spec:
replicas: 3
reserveGameServerIds:
- 3
- 4
- 5
- 6
...
# After a while
kubectl get gs
NAME STATE OPSSTATE DP UP AGE
minecraft-0 Ready None 0 0 10m
minecraft-1 Ready None 0 0 10m
minecraft-2 Ready None 0 0 10m
minecraft-5 Deleting None 0 0 9m55s
minecraft-6 Deleting None 0 0 9m55s
在缩容时，OKG将优先考虑被Reserve的游戏服，再按照上文提到的缩容顺序进行缩容
缩容策略
OKG 提供两种缩容策略：1）General；2）ReserveIds。您可在GameServerSet.Spec.ScaleStrategy.ScaleDownStrategyType设置对应策略
General
当用户不配置ScaleDownStrategyType字段，General为默认配置。缩容行为如上文中所述。
ReserveIds
用户设置ScaleDownStrategyType为ReserveIds，当游戏服集合发生缩容时，被删掉的游戏服尾部序号会被记录在reserveGameServerIds中，后续发生扩容时，这些尾部序号不会再使用；如果想再使用这些尾部序号，只需要将它们从reserveGameServerIds中拿出来同时调整副本数即可。
示例
例如，gss下存在5个游戏服，ID分别为0、1、2、3、4。此时设置GameServerSet.Spec.ScaleStrategy.ScaleDownStrategyType为ReserveIds，同时减少副本数目到3
kubectl edit gss minecraft
...
spec:
replicas: 3
scaleStrategy:
scaleDownStrategyType: ReserveIds
...
# After a while
kubectl get gs
NAME STATE OPSSTATE DP UP AGE
minecraft-0 Ready None 0 0 10m
minecraft-1 Ready None 0 0 10m
minecraft-2 Ready None 0 0 10m
minecraft-3 Deleting None 0 0 9m55s
minecraft-4 Deleting None 0 0 9m55s
...
kubectl get gss minecraft -o yaml
spec:
replicas: 3
reserveGameServerIds:
- 3
- 4
scaleStrategy:
scaleDownStrategyType: ReserveIds
可以看到，序号为3和4的游戏服被回填到了reserveGameServerIds字段，此时若希望指定4号游戏服扩容，则将4从reserveGameServerIds去除，并增加副本数到4：
kubectl edit gss minecraft
...
spec:
replicas: 4
reserveGameServerIds:
- 3
scaleStrategy:
scaleDownStrategyType: ReserveIds
...
# After a while
kubectl get gs
NAME STATE OPSSTATE DP UP AGE
minecraft-0 Ready None 0 0 17m
minecraft-1 Ready None 0 0 17m
minecraft-2 Ready None 0 0 17m
minecraft-4 Ready None 0 0 6s
通过该功能可以实现指定序号游戏服扩容。
配置游戏服的自动伸缩
GameServerSet支持HPA，您可以通过默认/自定义指标配置
HPA示例
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
name: minecraft-hpa
spec:
scaleTargetRef:
apiVersion: game.kruise.io/v1alpha1
kind: GameServerSet
name: minecraft # GameServerSet对应名称
minReplicas: 1
maxReplicas: 10
metrics:
- type: Resource
resource:
name: cpu
target:
type: Utilization
averageUtilization: 50 # 示例以cpu利用率50%为计算标准