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bot-bottle/tests/unit/test_macos_rootless_podman.py
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feat(macos): replace rootless Docker spike with rootless podman
Podman avoids the CAP_SYS_ADMIN requirement that makes rootless Docker
impossible here: with no subordinate UID range configured it falls back
to a single-UID self-mapping, which an unprivileged process may write
itself, so newuidmap is never invoked. The image build therefore strips
/etc/subuid and /etc/subgid entries rather than adding them.

The agent-facing surface is unchanged — docker and docker compose talk
to podman's Docker-compatible API socket.

Two device nodes need relaxing as root inside the bottle (0666 on
/dev/fuse and /dev/net/tun); both already exist and neither needs a
capability the bottle lacks, unlike CAP_SYS_ADMIN.

Verified live on macOS 26 / Apple Container 1.0.0: service starts with
zero added capabilities, compose pulls and serves from the workspace on
a published port, and a nested container cannot reach the network
outside the egress path.

Known limitation, not yet addressed: the agent base image is Debian
bookworm, whose podman 4.3.1 swallows container exit codes through the
compat API (docker run returns 0 regardless). podman 5.4.2 on trixie
fixes it; the base bump is a separate PR. The acceptance test asserts
on an in-band marker rather than an exit code so it cannot false-pass
in the meantime.

Nested containers give no isolation from the agent itself — root inside
one is the agent user outside it. They are a build/test convenience;
the bottle remains the security boundary.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GnMp8SUGH57hZX7192Rv2F
2026-07-21 12:59:10 -04:00

148 lines
5.8 KiB
Python

"""Unit coverage for the fail-closed macOS rootless-podman spike."""
from __future__ import annotations
import unittest
from dataclasses import dataclass
from pathlib import Path
from types import SimpleNamespace
from typing import cast
from unittest.mock import patch
from bot_bottle.backend.macos_container import rootless_podman
from bot_bottle.backend.macos_container import launch as launch_mod
from bot_bottle.backend.macos_container.bottle_plan import MacosContainerBottlePlan
class _Bottle:
def __init__(self, results: list[SimpleNamespace]) -> None:
self.results = results
self.commands: list[str] = []
def exec(self, command: str) -> SimpleNamespace:
self.commands.append(command)
return self.results.pop(0)
def _result(returncode: int, *, stdout: str = "", stderr: str = "") -> SimpleNamespace:
return SimpleNamespace(returncode=returncode, stdout=stdout, stderr=stderr)
@dataclass(frozen=True)
class _AgentProvision:
image: str
@dataclass(frozen=True)
class _Plan:
slug: str
image: str
dockerfile_path: str
docker_access: bool
agent_provision: _AgentProvision
class TestRootlessPodmanStart(unittest.TestCase):
def test_bootstraps_then_waits_for_guest_local_service(self) -> None:
bottle = _Bottle([_result(0), _result(1), _result(0)])
with patch.object(rootless_podman.time, "sleep"):
rootless_podman.start(bottle)
self.assertIn("rootless-podman-init", bottle.commands[0])
self.assertEqual(2, bottle.commands.count("docker info >/dev/null 2>&1"))
def test_bootstrap_failure_is_fatal_without_privilege_fallback(self) -> None:
bottle = _Bottle([_result(1, stderr="slirp4netns missing")])
with patch.object(rootless_podman, "die", side_effect=RuntimeError) as die:
with self.assertRaises(RuntimeError):
rootless_podman.start(bottle)
self.assertIn("slirp4netns missing", die.call_args.args[0])
self.assertEqual(1, len(bottle.commands))
def test_timeout_reports_guest_log(self) -> None:
bottle = _Bottle(
[_result(0)]
+ [_result(1) for _ in range(rootless_podman.READY_RETRIES)]
+ [_result(0, stdout="operation not permitted")]
)
with patch.object(rootless_podman.time, "sleep"), \
patch.object(rootless_podman, "die", side_effect=RuntimeError) as die:
with self.assertRaises(RuntimeError):
rootless_podman.start(bottle)
self.assertIn("operation not permitted", die.call_args.args[0])
class TestRootlessPodmanDevices(unittest.TestCase):
def test_relaxes_only_the_two_blocked_device_nodes_as_root(self) -> None:
calls: list[tuple[str, list[str]]] = []
rootless_podman.prepare_guest_devices(
"bottle-1", lambda name, argv: calls.append((name, argv)),
)
self.assertEqual(1, len(calls))
name, argv = calls[0]
self.assertEqual("bottle-1", name)
self.assertIn("chmod 0666 /dev/fuse /dev/net/tun", argv[-1])
class TestRootlessPodmanImage(unittest.TestCase):
def test_layers_tooling_without_changing_base_image(self) -> None:
calls: list[tuple[str, str, str]] = []
def build(image: str, context: str, *, dockerfile: str) -> None:
calls.append((image, context, dockerfile))
text = Path(dockerfile).read_text(encoding="utf-8")
self.assertIn("FROM agent:base", text)
self.assertIn("podman fuse-overlayfs slirp4netns uidmap", text)
self.assertIn("USER node", text)
self.assertTrue((Path(context) / "rootless-podman-init.sh").is_file())
image = rootless_podman.build_image("agent:base", build)
self.assertEqual("agent:base-rootless-podman", image)
self.assertEqual("agent:base-rootless-podman", calls[0][0])
def test_strips_subordinate_ranges_so_podman_avoids_newuidmap(self) -> None:
"""The single-UID fallback is the entire reason podman works here.
A subordinate range would send podman down the newuidmap path, which
cannot write a multi-range uid_map without CAP_SYS_ADMIN in an Apple
Container guest — the failure that killed the rootless-Docker spike.
"""
seen: list[str] = []
def build(image: str, context: str, *, dockerfile: str) -> None:
seen.append(Path(dockerfile).read_text(encoding="utf-8"))
rootless_podman.build_image("agent:base", build)
text = seen[0]
self.assertIn("sed -i '/^node:/d' /etc/subuid /etc/subgid", text)
self.assertNotIn("subuid", text.replace(
"sed -i '/^node:/d' /etc/subuid /etc/subgid", "",
))
def test_launch_builds_base_then_rootless_variant(self) -> None:
plan = cast(MacosContainerBottlePlan, cast(object, _Plan(
slug="dev-abc",
image="agent:base",
dockerfile_path="/repo/Dockerfile",
docker_access=True,
agent_provision=_AgentProvision(image="agent:base"),
)))
with patch.object(launch_mod, "read_committed_image", return_value=None), \
patch.object(launch_mod.container_mod, "build_image") as build, \
patch.object(
launch_mod.rootless_podman,
"build_image",
return_value="agent:base-rootless-podman",
) as build_rootless:
result = launch_mod._build_images(plan) # pylint: disable=protected-access
build.assert_called_once_with(
"agent:base", launch_mod._REPO_DIR, # pylint: disable=protected-access
dockerfile="/repo/Dockerfile",
)
build_rootless.assert_called_once_with("agent:base", build)
self.assertEqual("agent:base-rootless-podman", result.agent_provision.image)
if __name__ == "__main__":
unittest.main()