examples.md

Examples

For a more comprehensive list of examples, look in the examples\ directory.

Basic Hello World

{
  "script": "python -c \"import sys; print('Hello from MXC!'); print(f'Python version: {sys.version}');\"",
  "processContainer": {
    "name": "CLI-HelloWorld"
  }
}

Filesystem Access Control

{
  "script": "python -c \"open('C:\\\\temp\\\\output.txt', 'w').write('test')\"",
  "processContainer": {
    "name": "CLI-Filesystem-Test"
  },
  "filesystem": {
    "readwritePaths": [
      "C:\\temp"
    ],
    "deniedPaths": [
      "C:\\Windows\\System32"
    ],
    "clearPolicyOnExit": true
  }
}

Network Restricted Execution

{
  "script": "import urllib.request\nurllib.request.urlopen('https://api.github.com')",
  "network": {
    "defaultPolicy": "block",
    "enforcementMode": "firewall",
    "allowedHosts": ["api.github.com"]
  }
}

Schema 0.8 Directional Network Policy

Schema 0.8 adds a directional format with explicit egress CIDR, protocol, and port rules plus separate ingress defaults:

{
  "version": "0.8.0-alpha",
  "containment": "process",
  "process": {
    "commandLine": "echo schema 0.8 directional network example"
  },
  "network": {
    "egress": {
      "default": "deny",
      "allow": [
        {
          "to": [{ "cidr": "192.0.2.0/24" }],
          "ports": [{ "protocol": "tcp", "port": 443 }]
        }
      ]
    },
    "ingress": {
      "default": "deny",
      "hostLoopback": "deny"
    }
  }
}

See tests/examples/30_network_0_8_directional.json for the complete config and sandbox-policy/0.8.0/networking/networking.md for network modes and backend support.

Network Proxy

Route sandboxed traffic through a localhost proxy via the legacy network.proxy field. Supported by ProcessContainer (Windows), Bubblewrap (Linux), and Seatbelt (macOS) — see each backend's doc for enforcement specifics. Two mutually exclusive modes are available:

External proxy — connect to an already-running localhost proxy:

{
  "script": "python -c \"import urllib.request; print(urllib.request.urlopen('https://api.github.com').status)\"",
  "timeout": 30000,
  "processContainer": {
    "name": "CLI-Proxy",
    "capabilities": ["internetClient"]
  },
  "network": {
    "proxy": { "localhost": 8080 }
  }
}

Builtin test server — the executor launches its own minimal HTTP CONNECT proxy on an OS-assigned port (for integration testing only, not production):

{
  "script": "python -c \"import urllib.request; print(urllib.request.urlopen('https://api.github.com').status)\"",
  "timeout": 30000,
  "processContainer": {
    "name": "CLI-BuiltinProxy",
    "capabilities": ["internetClient"]
  },
  "network": {
    "proxy": { "builtinTestServer": true }
  }
}

When builtinTestServer is true, it must be the only key in the proxy object. Because it activates a deliberately-permissive, testing-only proxy (no auth, no body limits), it is not enabled by default: pass the --allow-testing-features flag to wxc-exec/lxc-exec/mxc-exec-mac. This is a separate axis from --experimental (which selects experimental backends and features). The MXC SDK exposes the same gate as the allowTestingFeatures spawn option, which must be set to true for a policy that uses builtinTestServer.

Schema 0.8 shape: egress / ingress / runtimeConfig.networkProxy

Starting at "version": "0.8.0-alpha", the egress/ingress/runtimeConfig.networkProxy shape replaces the legacy defaultPolicy/allowedHosts/blockedHosts/network.proxy fields above — a config must use one shape or the other, never both. This is the official, cross-backend schema (see docs/sandbox-policy/0.8.0/networking/networking.md for the full design and per-backend enforcement matrix), not a backend-specific format: it's parsed the same way regardless of containment. Each backend independently declares which parts of it — if any — it actually enforces; a backend that hasn't declared support for a given field rejects a config that sets it. Seatbelt (macOS) is currently the only backend with that support implemented (EGRESS_DEFAULT, INGRESS_DEFAULT, HOST_LOOPBACK, RUNTIME_PROXY — see docs/seatbelt/seatbelt-backend.md); other backends are expected to add their own declarations as separate follow-up work. On Seatbelt, runtimeConfig.networkProxy covers only the loopback-proxy case (network.proxy.localhost / loopback network.proxy.url); there is no schema-0.8 equivalent for a remote proxy URL or builtinTestServer. See docs/sandbox-policy/0.8.0/networking/schema-updates.md for the full field mapping and tests/examples/30_mac_network_schema_v2.json for a complete example:

{
  "version": "0.8.0-alpha",
  "containment": "seatbelt",
  "network": {
    "egress": { "default": "deny" },
    "ingress": { "default": "deny", "hostLoopback": "deny" }
  },
  "runtimeConfig": {
    "networkProxy": "http://127.0.0.1:8080"
  }
}