Files
DECNET/decnet/web/services/systemd_control.py
anti f2b3393669 chore: relicense to AGPL-3.0-or-later and add SPDX headers
Replaces LICENSE (GPLv3 -> AGPLv3) and prepends
`SPDX-License-Identifier: AGPL-3.0-or-later` to every source file
across decnet/, decnet_web/, tests/, scripts/, and tools/.

Rationale: closes the GPLv3 ASP loophole so any party operating a
modified DECNET as a network service must offer their modified
source. Personal copyright (Samuel Paschuan) + inbound=outbound
contributions make a future unilateral relicense infeasible.

- LICENSE: full AGPL-3.0 text (gnu.org/licenses/agpl-3.0.txt)
- COPYRIGHT: project copyright notice
- tools/add_spdx_headers.py: idempotent header injector
  (shebang- and PEP 263-aware)

Touches 1565 source files (.py, .ts, .tsx, .js, .jsx, .css, .sh).
No behavior change; comments only.
2026-05-22 21:04:16 -04:00

138 lines
4.6 KiB
Python

# SPDX-License-Identifier: AGPL-3.0-or-later
"""Thin async wrapper over ``systemctl`` for DECNET worker units.
The API process runs as the unprivileged ``decnet`` user and delegates
the actual start/stop to systemd via a scoped polkit rule (see
``deploy/polkit/50-decnet-workers.rules``). This module keeps the shell
surface area minimal:
* Unit names are always ``decnet-<name>.service`` — callers pass the
bare worker name and the ``.service`` suffix is bolted on here.
* ``asyncio.create_subprocess_exec`` — never ``shell=True``. Worker
names are also validated at the router boundary against
:data:`decnet.web.worker_registry.KNOWN_WORKERS`; the extra regex
check here is defence in depth.
* ``list_installed()`` results are cached for 30 seconds to keep the
status endpoint cheap under repeated REFRESH clicks.
"""
from __future__ import annotations
import asyncio
import re
import time
from typing import Set
from decnet.logging import get_logger
log = get_logger("web.systemd_control")
_UNIT_NAME_RE = re.compile(r"^[a-z][a-z0-9_-]*$")
_LIST_CACHE_TTL = 30.0
_cache: Set[str] | None = None
_cache_ts: float = 0.0
class SystemctlError(RuntimeError):
"""Non-zero exit from ``systemctl``. Carries returncode + stderr."""
def __init__(self, unit: str, returncode: int, stderr: str) -> None:
self.unit = unit
self.returncode = returncode
self.stderr = stderr
super().__init__(
f"systemctl failed on {unit}: rc={returncode} stderr={stderr!r}"
)
def _unit(name: str) -> str:
if not _UNIT_NAME_RE.match(name):
raise ValueError(f"invalid worker name: {name!r}")
return f"decnet-{name}.service"
async def _run(*argv: str) -> tuple[int, str, str]:
proc = await asyncio.create_subprocess_exec(
*argv,
stdout=asyncio.subprocess.PIPE,
stderr=asyncio.subprocess.PIPE,
)
stdout_b, stderr_b = await proc.communicate()
return (
proc.returncode if proc.returncode is not None else -1,
stdout_b.decode("utf-8", "replace"),
stderr_b.decode("utf-8", "replace"),
)
async def _systemctl(verb: str, name: str) -> None:
unit = _unit(name)
rc, _, stderr = await _run("systemctl", verb, unit)
if rc != 0:
log.warning("systemctl %s %s failed: rc=%s stderr=%s", verb, unit, rc, stderr.strip())
raise SystemctlError(unit=unit, returncode=rc, stderr=stderr.strip())
async def start(name: str) -> None:
"""Start ``decnet-<name>.service``. Raises :class:`SystemctlError`."""
await _systemctl("start", name)
async def stop(name: str) -> None:
"""Stop ``decnet-<name>.service``. Raises :class:`SystemctlError`.
Unused in v1 (bus-based STOP is authoritative) but kept for parity
so the supervisor contract is symmetric.
"""
await _systemctl("stop", name)
async def is_active(name: str) -> bool:
"""Return True iff ``systemctl is-active`` reports ``active``.
``is-active`` exits non-zero for inactive / failed / unknown units;
that is **not** an error here — it's a signal.
"""
unit = _unit(name)
_, stdout, _ = await _run("systemctl", "is-active", unit)
return stdout.strip() == "active"
async def list_installed(*, force: bool = False) -> Set[str]:
"""Return the set of worker names with unit files installed.
Parses ``systemctl list-unit-files 'decnet-*.service' --no-legend``
and strips the ``decnet-`` prefix + ``.service`` suffix off each
line. Cached for :data:`_LIST_CACHE_TTL` seconds; pass
``force=True`` to bypass.
"""
global _cache, _cache_ts
now = time.time()
if not force and _cache is not None and (now - _cache_ts) < _LIST_CACHE_TTL:
return set(_cache)
rc, stdout, stderr = await _run(
"systemctl", "list-unit-files", "decnet-*.service", "--no-legend",
)
if rc != 0:
# systemd missing / non-systemd host — treat as "nothing installed"
# and keep the UI rendering. Cache the empty result so we don't
# hammer the failing binary on every refresh.
log.info("list-unit-files failed (treating as empty): rc=%s stderr=%s", rc, stderr.strip())
_cache = set()
_cache_ts = now
return set()
names: Set[str] = set()
for line in stdout.splitlines():
token = line.split(None, 1)[0] if line.strip() else ""
if token.startswith("decnet-") and token.endswith(".service"):
names.add(token[len("decnet-"):-len(".service")])
_cache = names
_cache_ts = now
return set(names)
def reset_cache_for_tests() -> None:
global _cache, _cache_ts
_cache = None
_cache_ts = 0.0