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bot-bottle/bot_bottle/backend/firecracker/backend.py
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feat(backend): remove smolmachines; firecracker is the Linux default
Delete the smolmachines backend (the whole bot_bottle/backend/smolmachines
package and its tests). It had fatal Linux issues (TSI networking under
sustained use, exec-channel contention, no SIGWINCH) and is superseded by
the Firecracker backend (issue #342).

Backend selection now:
- default is macos-container on macOS, firecracker on KVM-capable Linux
  hosts, and docker as the last resort (was smolmachines).
- firecracker is selected on a KVM host even when the `firecracker`
  binary isn't installed, so start routes through its preflight and
  prints an install pointer (same UX as require_container), instead of
  silently falling back. Split is_host_capable() (Linux + KVM) out of
  is_available() (adds the binary check) to drive this.

Retarget the cross-backend tests (parity, print-parity, prepare,
workspace, freezer, selection) from smolmachines to firecracker rather
than dropping the coverage. Remove docker.util.image_id/save, which only
smolmachines used. Update README/AGENTS/example bottles and stale
comments; historical docs/prds are left as a point-in-time record.

BREAKING: BOT_BOTTLE_BACKEND=smolmachines now errors as unknown.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WBMWTEtQdJ4W5UrWuLHCck
2026-07-11 13:24:47 -04:00

98 lines
3.1 KiB
Python

"""FirecrackerBottleBackend — Linux microVM implementation.
Replaces smolmachines on Linux (issue #342): mature KVM-based
isolation via Firecracker, SSH control over a point-to-point TAP, and a
fail-closed nftables egress boundary. Selected by
`BOT_BOTTLE_BACKEND=firecracker` or `--backend=firecracker`.
"""
from __future__ import annotations
from contextlib import contextmanager
from pathlib import Path
from typing import Generator, Sequence
from ...agent_provider import AgentProvisionPlan
from ...egress import EgressPlan
from ...env import ResolvedEnv
from ...git_gate import GitGatePlan
from ...manifest import Manifest
from ...supervise import SupervisePlan
from .. import ActiveAgent, BottleBackend, BottleSpec
from . import cleanup as _cleanup
from . import enumerate as _enumerate
from . import launch as _launch
from . import resolve_plan as _resolve_plan
from . import util as _util
from .bottle import FirecrackerBottle
from .bottle_cleanup_plan import FirecrackerBottleCleanupPlan
from .bottle_plan import FirecrackerBottlePlan
class FirecrackerBottleBackend(
BottleBackend["FirecrackerBottlePlan", "FirecrackerBottleCleanupPlan"]
):
name = "firecracker"
@classmethod
def is_available(cls) -> bool:
return _util.is_available()
@classmethod
def is_host_capable(cls) -> bool:
"""Linux + KVM, regardless of whether the `firecracker` binary
is installed. Drives default-backend selection so a capable host
without the binary still lands on firecracker and gets an
install pointer at launch."""
return _util.is_host_capable()
def _preflight(self) -> None:
_resolve_plan.preflight()
def _build_guest_env(self, resolved_env: ResolvedEnv) -> dict[str, str]:
return _resolve_plan.build_guest_env(resolved_env)
def _resolve_plan(
self,
spec: BottleSpec,
*,
manifest: Manifest,
slug: str,
resolved_env: ResolvedEnv,
agent_provision_plan: AgentProvisionPlan,
egress_plan: EgressPlan,
git_gate_plan: GitGatePlan,
supervise_plan: SupervisePlan | None,
stage_dir: Path,
) -> FirecrackerBottlePlan:
return _resolve_plan.resolve_plan(
spec,
manifest=manifest,
slug=slug,
resolved_env=resolved_env,
agent_provision_plan=agent_provision_plan,
egress_plan=egress_plan,
supervise_plan=supervise_plan,
git_gate_plan=git_gate_plan,
stage_dir=stage_dir,
)
@contextmanager
def launch(
self, plan: FirecrackerBottlePlan
) -> Generator[FirecrackerBottle, None, None]:
with _launch.launch(plan, provision=self.provision) as bottle:
yield bottle
def prepare_cleanup(self) -> FirecrackerBottleCleanupPlan:
return _cleanup.prepare_cleanup()
def cleanup(self, plan: FirecrackerBottleCleanupPlan) -> None:
_cleanup.cleanup(plan)
def enumerate_active(self) -> Sequence[ActiveAgent]:
return _enumerate.enumerate_active()
def supervise_mcp_url(self, plan: FirecrackerBottlePlan) -> str:
return plan.agent_supervise_url