Kuvel, A service discovery plugin for Velocity. It will automatically discover Minecraft servers and register/unregister them in Velocity.
- Monitor Minecraft pods in a Kubernetes cluster and automatically register/unregister them with Velocity
- Create a LoadBalancer server and distribute players trying to join to the linked servers.
- Synchronize server names across multiple Velocity servers using Redis
The Plugin can be downloaded from Releases. Download Kuvel.jar
and install it into Velocity.
In order for Kuvel to monitor the server, you must request permission from Kubernetes to allow Velocity pods discovery Minecraft servers. For Velocity pods, please allow get/list/watch to Pods and ReplicaSets.
apiVersion: v1
kind: ServiceAccount
metadata:
name: velocity-account
namespace: default
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: velocity-clusterrolebiding
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: view
subjects:
- kind: ServiceAccount
name: velocity-account
namespace: default
# Apply ServiceAccount to the Velocity pod
apiVersion: apps/v1
kind: ...
# ...
spec:
serviceAccountName: velocity-account
# ...
To tell Kuvel that the pod is a Minecraft server, use Label feature of Kubernetes.
Label Name | Value |
---|---|
minecraftServiceDiscovery | true / false |
minecraftServerName | Name of the server you wish to register with Velocity |
apiVersion: v1
kind: Pod
metadata:
name: test-server
labels:
minecraftServiceDiscovery: "true" # Required for Kuvel to detect Minecraft servers.
minecraftServerName: "test-server" # Required for Kuvel to name the server
spec:
containers:
- name: test-server
image: itzg/minecraft-server:java8
ports:
- containerPort: 25565
apiVersion: apps/v1
kind: Deployment
metadata:
name: test-server-deployment
spec:
replicas: 2
selector:
matchLabels:
app: test-server-deployment
template:
metadata:
labels:
app: test-server-deployment
minecraftServiceDiscovery: "true" # Required for Kuvel to detect Minecraft servers.
minecraftServerName: "test-server" # Required for Kuvel to name the server
spec:
containers:
- name: test-server
image: itzg/minecraft-server:java8
ports:
- containerPort: 25565
In both cases, the server is registered under the name test-server
.
However, if there are two or more servers with the same name, a number will be assigned after the server name. Specifically, if there are two pods with the server name test-server
, one will be test-server
and the other will be test-server-1
.
On parallelizable servers such as Lobby, it is sometimes desirable to distribute the number of players as much as possible. This is where Kuvel's LoadBalancer feature comes in handy.
apiVersion: apps/v1
kind: Deployment
metadata:
name: lobby-deployment
labels:
minecraftServiceDiscovery: "true"
minecraftServerName: "lobby"
spec:
replicas: 3
selector:
matchLabels:
app: lobby-deployment
template:
metadata:
labels:
app: lobby-deployment
minecraftServiceDiscovery: "true"
minecraftServerName: "lobby"
spec:
containers:
- name: lobby
image: itzg/minecraft-server:java8
ports:
- containerPort: 25565
By applying a Label to a Deployment, Kuvel's LoadBalancer feature can be activated.
- Distribute players who try to join the Load Balancer server to the pods under ReplicaSet.
- Synchronize with Kubernetes ReplicaSet and automatically register/unregister forwarding destinations
Using this, you can implement a mechanism to randomly connect to lobby-1
, lobby-2
, or lobby-3
when /server lobby
is invoked.
In a Kubernetes cluster, pods can be created at almost the same time, and this can cause a fatal problem in a parallel Velocity environment because it is possible that different Velocity servers have different registration names. Kuvel provides name synchronization using Redis to avoid this problem.
To enable this feature, simply set redis.enable
to true
in config.yml. Kuvel uses keys whose key name begins with kuvel:
.
redis:
enable: true # Setting it to true enables server name synchronization using Redis
group-name: "production" # Name synchronization is performed only between servers with the same Redis server and the same group-name
connection:
hostname: "localhost"
port: 6379
username: "root"
password: "password"