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Use K8s Only

INFO

This guide is intended for users who are familiar with Kubernetes. It does not cover how to set up a Kubernetes cluster or provide tutorials on using kubectl. Additionally, this guide may include some advanced Kubernetes terminology, so a certain level of familiarity is required for reading.

This article focuses on deploying GZCTF in a Kubernetes cluster. For configuration instructions specific to GZCTF itself, please refer to the Quick Start guide.

Deployment Notes

GZCTF supports multi-instance deployment, but based on testing, currently the most stable deployment method is a single-instance deployment with the database on the same node. Therefore, this article will focus on single-instance deployment as an example.
For multi-instance deployment, all instances need to mount the shared storage as Persistent Volumes (PV) to ensure file consistency. Additionally, Redis needs to be deployed to ensure cache consistency among multiple instances.
For multi-instance deployment, the load balancer needs to be configured with sticky sessions to enable real-time data retrieval using websockets.
If you prefer a simpler deployment, go for a single-instance deployment!
Since you have chosen to deploy with Kubernetes, it implies that you need a larger number of Pods. Please pay attention to the following configuration:
- Specify --kube-controller-manager-arg=node-cidr-mask-size=16 during installation. The default CIDR is /24, supporting a maximum of 255 Pods. This cannot be changed after installation.
  INSTALL_K3S_EXEC="--kube-controller-manager-arg=node-cidr-mask-size=16"
- Adjust the value of maxPods accordingly, otherwise you may reach the Pod limit and be unable to schedule more Pods.
  apiVersion: kubelet.config.k8s.io/v1beta1 kind: KubeletConfiguration maxPods: 800

Deploying GZCTF

Create namespaces and configuration files

apiVersion: v1
kind: Namespace
metadata:
  name: gzctf-server
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: gzctf-config
  namespace: gzctf-server
data:
  appsettings.json: |
    { ... } # content of appsettings.json
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: gzctf-sa
  namespace: gzctf-server
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: gzctf-crb
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin # use to access the Kubernetes API
subjects:
  - kind: ServiceAccount
    name: gzctf-sa
    namespace: gzctf-server
---
apiVersion: v1
kind: Secret
metadata:
  name: gzctf-tls
  namespace: gzctf-server
type: kubernetes.io/tls
data:
  tls.crt: ... # base64 encoded TLS certificate
  tls.key: ... # base64 encoded TLS private key

Create local PV (if you need to share storage among multiple instances, please change the configuration yourself)

apiVersion: v1
kind: PersistentVolume
metadata:
  name: gzctf-files-pv
  namespace: gzctf-server
spec:
  capacity:
    storage: 2Gi
  accessModes:
    - ReadWriteOnce # Please change to ReadWriteMany when deploying multiple instances
  hostPath:
    path: /mnt/path/to/gzctf/files # local path
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: gzctf-db-pv
  namespace: gzctf-server
spec:
  capacity:
    storage: 1Gi
  accessModes:
    - ReadWriteOnce
  hostPath:
    path: /mnt/path/to/gzctf/db # local path
apiVersion: v1
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: gzctf-files
  namespace: gzctf-server
spec:
  accessModes:
    - ReadWriteOnce # Please change to ReadWriteMany when deploying multiple instances
  resources:
    requests:
      storage: 2Gi
  volumeName: gzctf-files-pv
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: gzctf-db
  namespace: gzctf-server
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi
  volumeName: gzctf-db-pv

Create the Deployment manifest of GZCTF

apiVersion: apps/v1
kind: Deployment
metadata:
  name: gzctf
  namespace: gzctf-server
  labels:
    app: gzctf
spec:
  replicas: 1
  strategy:
    type: RollingUpdate
  selector:
    matchLabels:
      app: gzctf
  template:
    metadata:
      labels:
        app: gzctf
    spec:
      serviceAccountName: gzctf-sa
      nodeSelector:
        kubernetes.io/hostname: xxx # Specify the deployment node, forcing it to be on the same node as the database
      containers:
        - name: gzctf
          image: gztime/gzctf:latest
          imagePullPolicy: Always
          env:
            - name: GZCTF_ADMIN_PASSWORD
              value: xxx # Admin password
            # choose your backend language `en_US` / `zh_CN` / `ja_JP`
            - name: LC_ALL
              value: en_US.UTF-8
          ports:
            - containerPort: 8080
              name: http
          volumeMounts:
            - name: gzctf-files
              mountPath: /app/files
            - name: gzctf-config
              mountPath: /app/appsettings.json
              subPath: appsettings.json
          resources:
            requests:
              cpu: 1000m
              memory: 384Mi
      volumes:
        - name: gzctf-files
          persistentVolumeClaim:
            claimName: gzctf-files
        - name: gzctf-config
          configMap:
            name: gzctf-config
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: gzctf-redis
  namespace: gzctf-server
  labels:
    app: gzctf-redis
spec:
  replicas: 1
  selector:
    matchLabels:
      app: gzctf-redis
  template:
    metadata:
      labels:
        app: gzctf-redis
    spec:
      containers:
        - name: gzctf-redis
          image: redis:alpine
          imagePullPolicy: Always
          ports:
            - containerPort: 6379
              name: redis
          resources:
            requests:
              cpu: 10m
              memory: 64Mi
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: gzctf-db
  namespace: gzctf-server
  labels:
    app: gzctf-db
spec:
  replicas: 1
  selector:
    matchLabels:
      app: gzctf-db
  template:
    metadata:
      labels:
        app: gzctf-db
    spec:
      nodeSelector:
        kubernetes.io/hostname: xxx # Specify the deployment node, need to be on the same node as GZCTF
      containers:
        - name: gzctf-db
          image: postgres:alpine
          imagePullPolicy: Always
          ports:
            - containerPort: 5432
              name: postgres
          env:
            - name: POSTGRES_PASSWORD
              value: xxx # Database password, needs to be consistent with the database password in appsettings.json
          volumeMounts:
            - name: gzctf-db
              mountPath: /var/lib/postgresql/data
          resources:
            requests:
              cpu: 500m
              memory: 512Mi
      volumes:
        - name: gzctf-db
          persistentVolumeClaim:
            claimName: gzctf-db

Create Service and Ingress

apiVersion: v1
kind: Service
metadata:
  name: gzctf
  namespace: gzctf-server
  annotations: # Enable Traefik Sticky Session
    traefik.ingress.kubernetes.io/service.sticky.cookie: "true"
    traefik.ingress.kubernetes.io/service.sticky.cookie.name: "LB_Session"
    traefik.ingress.kubernetes.io/service.sticky.cookie.httponly: "true"
spec:
  selector:
    app: gzctf
  ports:
    - protocol: TCP
      port: 8080
      targetPort: 8080
---
apiVersion: v1
kind: Service
metadata:
  name: gzctf-db
  namespace: gzctf-server
spec:
  selector:
    app: gzctf-db
  ports:
    - protocol: TCP
      port: 5432
      targetPort: 5432
---
apiVersion: v1
kind: Service
metadata:
  name: gzctf-redis
  namespace: gzctf-server
spec:
  selector:
    app: gzctf-redis
  ports:
    - protocol: TCP
      port: 6379
      targetPort: 6379
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: gzctf
  namespace: gzctf-server
  annotations: # Some TLS settings for Traefik, you can modify them to satisfy your needs
    kubernetes.io/ingress.class: "traefik"
    traefik.ingress.kubernetes.io/router.tls: "true"
    ingress.kubernetes.io/force-ssl-redirect: "true"
spec:
  tls:
    - hosts:
        - ctf.example.com # Domain name
      secretName: gzctf-tls # Certificate name, you need to create the corresponding Secret yourself
  rules:
    - host: ctf.example.com # Domain name
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: gzctf
                port:
                  number: 8080

Additional Configuration for Traefik

In order to make GZCTF able to obtain the real IP address of users through XFF, Traefik needs to be able to add the XFF header correctly. Please note that the following content may not always be up-to-date and applicable to all versions of Traefik. This is an example of helm values, please search for the latest configuration method yourself.

service:
  spec:
externalTrafficPolicy: Local # To make XFF work properly, set externalTrafficPolicy to Local
deployment:
  kind: DaemonSet
ports:
  web:
  redirectTo: websecure # Redirect HTTP to HTTPS
additionalArguments:
  - "--entryPoints.web.proxyProtocol.insecure"
  - "--entryPoints.web.forwardedHeaders.insecure"
  - "--entryPoints.websecure.proxyProtocol.insecure"
  - "--entryPoints.websecure.forwardedHeaders.insecure"

Deployment Tips

If you want GZCTF to automatically create an admin account during initialization, make sure to pass the GZCTF_ADMIN_PASSWORD environment variable. Otherwise, you will need to manually create the admin account.
Please debug and verify if GZCTF can correctly retrieve the real IP address of users on the system log page. If not, check if the Traefik configuration is correct.
If you want to monitor the resource usage, please deploy Prometheus and Grafana on your own, enable Prometheus support in Traefik, and monitor the resource usage of the challenge containers using node exporter.
If you need to automatically update the deployment of GZCTF based on the configuration file, please refer to Reloader.
Inside the cluster, you can use https://kubernetes.default.svc.cluster.local:443 as the server field in the cluster configuration file.

Table of Contents

#Use K8s Only

#Deployment Notes

#Deploying GZCTF

#Deployment Tips

Use K8s Only

Deployment Notes

Deploying GZCTF

Deployment Tips