secure-sandboxtemplate.yaml

# Restrict Pod-to-Pod Communication: The presence of the 'networkPolicy' block causes the controller 
# to create a unique NetworkPolicy for each sandbox. This individual policy is what guarantees 
# that sandbox-1 cannot talk to sandbox-2.

# Only Allow Pod Ingress from MST L7XLB: The 'ingress' list explicitly defines the L7XLB's labels 
# as the only allowed ingress source.

# Only Allow Egress if Required:
# We explicitly create a rule to allow TCP and UDP traffic on port 53.
# This ensures DNS resolution works regardless of the cluster's DNS provider (CoreDNS, NodeLocal DNS, Cloud DNS, etc.).
# By providing only this rule in 'egress', we are declaring that no other traffic is required.

# Don't Allow Access to API Server: This is a direct result of the "default-deny" egress policy. 
# Since there is no rule in 'egress' that allows traffic to the API server IPs, it is blocked.
apiVersion: extensions.agents.x-k8s.io/v1alpha1
kind: SandboxTemplate
metadata:
  name: secure-datascience-template
  namespace: default
spec:
  podTemplate:
    spec:
      # This pod uses a non-root user and gVisor for runtime sandboxing.
      runtimeClassName: gvisor
      securityContext:
        runAsUser: 1000
        runAsGroup: 3000
        fsGroup: 2000
        runAsNonRoot: true
      containers:
      - name: my-container
        image: busybox
        command: ["/bin/sh", "-c", "sleep 36000"]
        ports:
        - containerPort: 8888
          protocol: TCP

  # 2. Define the Network Policy to enforce the security requirements.
  networkPolicy:
    # WARNING: Sidecars (like Istio/Datadog) needing extra ingress ports must be
    # explicitly allowed via the 'ingress' list below.

    # REQUIREMENT #3: Only allow pod ingress from MST L7XLB.
    # This section defines the trusted ingress source using standard K8s syntax.
    # Traffic from any other source, including other sandbox pods, will be blocked.
    ingress:
      - from:
        - namespaceSelector:
            matchLabels:
              istio-injection: enabled
          podSelector:
            matchLabels:
              app: istio-ingressgateway
    
    # REQUIREMENT #2 & #4: Only allow egress if required & block API server access.
    # We must explicitly allow DNS (Port 53), otherwise the Pod cannot resolve names.
    # By listing ONLY DNS here, we implicitly block all other outgoing traffic,
    # including connections to the Kubernetes API server and other pods.
    egress:
      - ports:
        - protocol: UDP
          port: 53
        - protocol: TCP
          port: 53