Container isolation

How HexaHost GameCloud isolates Minecraft server workloads on game nodes.

Model

Each customer server runs as a non-privileged Docker container on a dedicated game node. The node-agent creates and manages containers; customers never receive Docker socket access.

Control plane (trusted)  ──mTLS──►  Node agent (trusted)  ──►  Game container (untrusted)

Container hardening (target profile)

Control	Setting
User	Non-root UID inside container
Privileges	`--privileged=false`
Capabilities	Drop ALL, add only required (none for vanilla Java)
seccomp	Docker default or custom profile (Phase 2)
AppArmor	Docker default profile
Network	Bridge network per server; no `host` network mode
Read-only root	Where compatible with selected software family
Memory / CPU	cgroup limits from plan slug
PIDs limit	Prevents fork bombs

Network isolation

Game containers reach the internet for Minecraft auth and mod downloads only through controlled egress
No route to control plane PostgreSQL, Redis, or internal APIs
Node-agent management port (9100) bound to localhost or management VLAN only

See threat T05 and T12 in threat model.

Storage isolation

Per-server data directory on node disk: /var/lib/hgc-node/servers/{serverId}/
Path traversal prevented server-side; symlinks rejected on archive extract
Backups uploaded to object storage — not readable by other tenants

Image policy

Only catalog-approved runtime images (digest-pinned)
Customers cannot push custom images
Periodic image vulnerability scan in CI (Phase 9)

Multi-tenant on one node

The scheduler enforces RAM and server count limits per node. There is no shared filesystem between server containers except the read-only image layers.

Operator responsibilities

Task	Frequency
Docker security updates on nodes	Monthly
Review AppArmor/seccomp profiles after Minecraft/Java major bumps	Per release
Audit `docker ps` for unexpected privileged containers	Weekly

Bootstrap hardening via deploy/ansible/game-node.yml.

Verification

Attempt cross-container network scan from test server (should fail to reach agent port)
Confirm docker inspect shows Privileged: false
Penetration test before production go-live

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