mc-router/docs/k8s-autoscale.yaml

# This YAML is an example and is not intended to be directly applied.
# It consists of 3 parts
# 1. the mc-router with service account an service 
# 2. the shutdown cronjob with service account
# 3. the actual server with service and storage

# part 3 is the only part you need to replicate for the number of servers you want

# mc-router
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: mc-router
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: services-watcher
rules:
- apiGroups: [""]
  resources: ["services"]
  verbs: ["watch","list"]
- apiGroups: ["apps"]
  resources: ["statefulsets", "statefulsets/scale"]
  verbs: ["watch","list","get","update"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: mc-router-services-watcher
subjects:
- kind: ServiceAccount
  name: mc-router
  namespace: default
roleRef:
  kind: ClusterRole
  name: services-watcher
  apiGroup: rbac.authorization.k8s.io
# Use whatever tcp ingress method you want I just used a node port here for simplicity
---
apiVersion: v1
kind: Service
metadata:
  name: mc-router
spec:
  type: NodePort
  externalIPs:
    - 192.168.1.100
  ports:
  - targetPort: web
    name: web
    port: 8080
    nodePort: 30001
  - targetPort: proxy
    name: proxy
    port: 25565
    nodePort: 30000
  selector:
    run: mc-router
---
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    run: mc-router
  name: mc-router
spec:
  selector:
    matchLabels:
      run: mc-router
  strategy:
    type: Recreate
  template:
    metadata:
      labels:
        run: mc-router
    spec:
      serviceAccountName: mc-router
      containers:
      - image: aapjeisbaas/mc-router:latest
        imagePullPolicy: Always
        name: mc-router
        args: ["--api-binding", ":8080", "--in-kube-cluster","--auto-scale-up", "--debug"]
        env:
          - name: AUTO_SCALE_UP
            value: "true"
        ports:
        - name: proxy
          containerPort: 25565
        - name: web
          containerPort: 8080
        resources:
          requests:
            memory: 50Mi
            cpu: "100m"
          limits:
            memory: 100Mi
            cpu: "250m"


# Cron job for stopping empty servers
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: mc-shutdown
rules:
- apiGroups: ["apps"]
  resources: ["statefulsets", "statefulsets/scale"]
  verbs: ["list","get","update", "patch"]
- apiGroups: [""]
  resources: ["pods", "pods/log"]
  verbs: ["get", "list"]
- apiGroups: [""]
  resources: ["pods/exec"]
  verbs: ["create"]
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: mc-shutdown
subjects:
- kind: ServiceAccount
  name: mc-shutdown
  namespace: default
roleRef:
  kind: ClusterRole
  name: mc-shutdown
  apiGroup: "rbac.authorization.k8s.io"
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: mc-shutdown
---
apiVersion: batch/v1
kind: CronJob
metadata:
  name: mc-shutdown
spec:
  schedule: "*/5 * * * *"
  concurrencyPolicy: Forbid
  jobTemplate:
    spec:
      template:
        spec:
          serviceAccountName: mc-shutdown
          restartPolicy: OnFailure
          containers:
          - name: shutdown
            image: bitnami/kubectl:latest
            imagePullPolicy: IfNotPresent
            command:
            - /bin/bash
            - -c
            - source shutdown-script.sh
            volumeMounts:
                - name: shutdown-script
                  mountPath: /shutdown-script.sh
                  subPath: shutdown-script.sh
                  readOnly: true
          volumes:
          - name: shutdown-script
            configMap:
              name: shutdown-script
              items:
                - key: shutdown-script.sh
                  path: shutdown-script.sh
# uses container label containertype=minecraft-server to find running servers
# TODO: get ownerReferences link to StatefulSet/name from pod metadate instead of sed string manipulation
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: shutdown-script
data:
  shutdown-script.sh: |
    #!/bin/bash
    MC_PODS=$(kubectl get pods -l containertype=minecraft-server -o=jsonpath="{range .items[*]}{.metadata.name},"| sed 's/,/\n/g') 
    for p in $MC_PODS; do
      echo "found minecraft pod $p, sleeping 120 seconds to prevent shutdown before login"
      sleep 120
      deployment=$(echo $p |sed 's/-0//g')
      # check online player count in the mc server
      if [[ $(kubectl exec -i $p -- /usr/local/bin/mc-monitor status) == *"online=0"* ]] ;then
        kubectl scale statefulset $deployment --replicas=0
      fi
    done    


# The actual minecraft servers, services and storage, repeat this block for as many servers as you want
# make sure you have the label containertype=minecraft-server this is used to find running servers
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: minecraft-servername-deployment
  labels:
    app: minecraft-servername-container
spec:
  serviceName: minecraft-servername-deployment
  selector:
    matchLabels:
      app: minecraft-servername-container 
  replicas: 0
  template:
    metadata:
      labels:
        app: minecraft-servername-container
        containertype: minecraft-server
    spec:
      containers:
      - name: minecraft-servername-deployment
        image: itzg/minecraft-server:latest
        imagePullPolicy: IfNotPresent
        resources:
          limits:
            memory: "2048Mi"
        env:
          # Use secret in real usage
        - name: EULA
          value: "true"
        # let the JVM figure out mem management
        - name: "MEMORY"
          value: ""
        - name: JVM_XX_OPTS
          value: "-XX:MaxRAMPercentage=75"
        ports:
        - containerPort: 25565
          name: main
        readinessProbe:
          exec:
            command: [ "/usr/local/bin/mc-monitor", "status", "--host", "localhost" ]
          # Give it i + p * f seconds to be ready, so 120 seconds
          initialDelaySeconds: 20
          periodSeconds: 5
          failureThreshold: 20
        # Monitor ongoing liveness
        livenessProbe:
          exec:
            command: ["/usr/local/bin/mc-monitor", "status", "--host", "localhost"]
          initialDelaySeconds: 120
          periodSeconds: 60
        volumeMounts:
        - name: mc-data
          mountPath: /data
      volumes:
      - name: mc-data
        persistentVolumeClaim:
          claimName: minecraft-servername-pvc
          readOnly: false
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: minecraft-servername-pvc
  namespace: default
spec:
  accessModes:
  - ReadWriteMany
  resources:
    requests:
      storage: 20Gi
---
apiVersion: v1
kind: Service
metadata:
  name: minecraft-servername-deployment
  namespace: default
  annotations:
    "mc-router.itzg.me/externalServerName": "your-awesome-server.public-domain.com"
spec:
  ports:
  - port: 25565
  selector:
    app: minecraft-servername-container