MINECRAFTBIBLE
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Server-discovery Velocity plugin for Minecraft servers running in a Kubernetes cluster.
Kuvel, A service discovery plugin for Velocity. It will automatically discover Minecraft servers and
register/unregister them within Velocity.
The Plugin can be downloaded
from Releases. Download Kuvel.jar and
install it into Velocity plugins directory. The config file requires initial setup as seen below.
# The kubernetes namespace to use for the server discovery.
namespace: ""
# The prefix to use for the keys of the server labels or annotations.
label-key-prefix: "kuvel.azisaba.net"
# Server name synchronization by Redis is required in load-balanced environments using multiple Velocity instances.
redis:
group-name: "develop"
connection:
hostname: "redis"
port: 6379
# username is optional. if you have authentication enabled, you can use it here. Otherwise you can leave it blank or null.
username: "default"
# password is optional. if you have authentication enabled, you can use it here. Otherwise you can leave it blank or null.
password: "password"
# label-selectors are used to filter Pods and ReplicaSets to be registered.
label-selectors:
- "kuvel.azisaba.net/enable-server-discovery=true"
Alternatively you can use environment variables to configure Kuvel. The environment variable will override
the config.yml and are KUVEL_NAMESPACE, KUVEL_LABEL_KEY_PREFIX, KUVEL_REDIS_GROUPNAME,KUVEL_REDIS_CONNECTION_HOSTNAME, KUVEL_REDIS_CONNECTION_PORT, KUVEL_REDIS_CONNECTION_USERNAME, andKUVEL_REDIS_CONNECTION_PASSWORD.
In order for Kuvel to monitor the server, you must request permission from Kubernetes. 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 the Kubernetes label service.
The label keys and values are specified in the config file. By default, the label key
is kuvel.azisaba.net/enable-server-discovery and the value is true.
The following labels are also used for some other features.
| Label Name | Value |
|---|---|
| kuvel.azisaba.net/preferred-server-name | Name of the server you wish to register with Velocity |
| kuvel.azisaba.net/initial-server | true / false |
| kuvel.azisaba.net/disable-name-suffix | true / false |
If server names longer than 63 characters are desired, the kuvel.azisaba.net/preferred-server-name annotation can be used instead of the label.
If kuvel.azisaba.net/disable-name-suffix=true is set on a Pod, Kuvel will register the server name exactly as preferred-server-name (no -1 suffix). If multiple replicas are detected, Kuvel logs an error and skips the extra pods. This label is intended for single-replica Pods only.
apiVersion: v1
kind: Pod
metadata:
name: test-server
labels:
kuvel.azisaba.net/enable-server-discovery: "true" # Required for Kuvel to detect Minecraft servers. Depends on your config.
kuvel.azisaba.net/preferred-server-name: "test-server" # Required for Kuvel to name the server
# kuvel.azisaba.net/initial-server: "true" # Uncomment this line if you want to make this server the initial server.
# kuvel.azisaba.net/disable-name-suffix: "true" # Use the exact preferred name (no -1 suffix); single replica only.
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
kuvel.azisaba.net/enable-server-discovery: "true" # Required for Kuvel to detect Minecraft servers. Depends on your config.
kuvel.azisaba.net/preferred-server-name: "test-server" # Required for Kuvel to name the server
# kuvel.azisaba.net/initial-server: "true" # Uncomment this line if you want to make this server the initial 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. For example, 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 servers, it is sometimes desirable to distribute the number of players as evenly as possible. This is where Kuvel's LoadBalancer feature comes in handy.
apiVersion: apps/v1
kind: Deployment
metadata:
name: lobby-deployment
labels:
kuvel.azisaba.net/enable-server-discovery: "true"
kuvel.azisaba.net/preferred-server-name: "lobby"
# kuvel.azisaba.net/initial-server: "true" # Uncomment this line if you want to make this load balancer server the initial server.
spec:
replicas: 3
selector:
matchLabels:
app: lobby-deployment
template:
metadata:
labels:
app: lobby-deployment
kuvel.azisaba.net/enable-server-discovery: "true"
kuvel.azisaba.net/preferred-server-name: "lobby"
# kuvel.azisaba.net/initial-server: "true" # Uncomment this line if you want to make this server the initial server.
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. Kuvel's LoadBalancer has the following features.
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 different
Velocity servers to have different registration names. This can cause fatal issues in a parallel
Velocity environment. Kuvel provides name synchronization using Redis to avoid this
issue. Kuvel uses keys whose key name begins with kuvel:.
On 1.x, this feature was optional, but from 2.0.0, this setting is enabled by default.