apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: agent-image-puller
  namespace: swarm-system
  labels:
    app: agent-image-puller
    component: optimization
spec:
  selector:
    matchLabels:
      app: agent-image-puller
  template:
    metadata:
      labels:
        app: agent-image-puller
    spec:
      # Run on all nodes including control plane
      tolerations:
      - key: node-role.kubernetes.io/control-plane
        operator: Exists
        effect: NoSchedule
      - key: node-role.kubernetes.io/master
        operator: Exists
        effect: NoSchedule

      # Use host network to avoid CNI overhead
      hostNetwork: true

      initContainers:
      # Pre-pull the agent image
      - name: pull-agent-image
        image: ghcr.io/heicode/swarm-agent:latest
        command: ['sh', '-c', 'echo "Agent image pulled successfully"']
        resources:
          limits:
            memory: "128Mi"
            cpu: "100m"

      # Pre-pull common base images
      - name: pull-python-base
        image: python:3.11-slim
        command: ['sh', '-c', 'echo "Python base image pulled"']
        resources:
          limits:
            memory: "128Mi"
            cpu: "100m"

      containers:
      # Keep-alive container (does nothing but keeps DaemonSet running)
      - name: pause
        image: gcr.io/google_containers/pause:3.9
        resources:
          limits:
            memory: "32Mi"
            cpu: "10m"
          requests:
            memory: "16Mi"
            cpu: "5m"

      # Optional: Periodic re-pull to get latest images
      - name: periodic-puller
        image: docker:24-cli
        command:
        - /bin/sh
        - -c
        - |
          while true; do
            echo "Checking for image updates..."
            # This would require docker socket mount in production
            # For now, just sleep
            sleep 3600  # Re-check every hour
          done
        resources:
          limits:
            memory: "64Mi"
            cpu: "50m"
        volumeMounts:
        - name: docker-socket
          mountPath: /var/run/docker.sock
          readOnly: true

      volumes:
      - name: docker-socket
        hostPath:
          path: /var/run/docker.sock
          type: Socket

      # Ensure DaemonSet runs before agent pods
      priorityClassName: system-node-critical