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FabledSteward/steward/core/alerts.py
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bvandeusenandClaude Opus 5.5 3c24c633df
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fix(ansible): overlapping runs: one per host, one per schedule, one action run per alert rule (#5158)
- One run per host: start_run claims every host it touches (addresses read
  from the inventory Steward wrote; a source's own inventory file is claimed
  as that file) before it takes a run slot. The claim is all-or-nothing. A run
  waiting on a host shows queued and names the run it waits for, honours a
  cancel, and fails after HOST_WAIT_SECONDS (1 h) with which host and run.
- A due schedule whose previous run is still queued or running skips the
  firing: last_run_at moves on, last_run_id still names the run going, and
  last_error says "Skipped: the previous run was still going". The Schedules
  page shows that beside the run (muted), and a launch error in red.
- An alert rule that fires while the action run from an earlier firing is
  still going starts no new run; the event says so and names the run. An
  in-process set closes the gap between the check and the run being linked.
- docs/core/ansible.md: queued/cancelled statuses and the overlap rules.

Tests: tests/core/test_ansible_overlap.py (claim keys, waiting, all-or-nothing,
cancel, deadline) and tests/integration/test_ansible_overlap.py (two real
runs on one host take turns; schedule skip then fire; alert action skip then
start).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-06 21:24:51 -04:00

667 lines
26 KiB
Python

from __future__ import annotations
import asyncio
import logging
import uuid
from dataclasses import dataclass
from datetime import datetime, timedelta, timezone
from typing import TYPE_CHECKING
from sqlalchemy import event as sa_event, select
from sqlalchemy.ext.asyncio import AsyncSession
from steward.models.alerts import (
AlertEvent,
AlertOperator,
AlertRule,
AlertState,
AlertStateEnum,
MaintenanceWindow,
)
from steward.core.formatting import human_duration
from steward.models.metrics import PluginMetric
if TYPE_CHECKING:
from quart import Quart
logger = logging.getLogger(__name__)
_app: "Quart | None" = None
def init_alerts(app: "Quart") -> None:
"""Store app reference for use in notification dispatch tasks."""
global _app
_app = app
def alert_extra_vars(rule: AlertRule, value: float) -> dict:
"""Ansible extra-vars describing the alert that fired.
Injected into every alert-triggered playbook run so the playbook can target
the exact resource/metric that fired without templating. They reach
ansible-playbook in its JSON extra-vars file, not as `-e key=value`, which
Ansible splits on whitespace: a rule named "High CPU on web" stays one
value (#5157). Pure function.
"""
return {
"steward_alert_rule": rule.name,
"steward_alert_source": rule.source_module,
"steward_alert_resource": rule.resource_name,
"steward_alert_metric": rule.metric_name,
"steward_alert_value": value,
"steward_alert_threshold": rule.threshold,
"steward_alert_operator": rule.operator.value,
}
def action_vars(lines) -> dict:
"""An alert action's stored `key=value` lines as a map, split at the first
`=` so a value keeps its spaces, quotes and further `=`."""
out: dict = {}
for line in lines or ():
key, sep, val = str(line).partition("=")
if sep and key.strip():
out[key.strip()] = val
return out
async def record_metric(
session: AsyncSession,
source_module: str,
resource_name: str,
metric_name: str,
value: float,
) -> None:
"""One metric sample: record_metrics with a single row."""
await record_metrics(session, [PluginMetric(
source_module=source_module, resource_name=resource_name,
metric_name=metric_name, value=value)])
class MetricBatch:
"""Gathers one transaction's samples so they are recorded, and their alert
rules evaluated, in a single record_metrics call:
batch = MetricBatch()
batch.add(source_module="unifi", resource_name="wan", metric_name="is_up", value=1.0)
await batch.record(session)
"""
def __init__(self) -> None:
self.rows: list[PluginMetric] = []
def add(self, source_module: str, resource_name: str, metric_name: str, value: float,
recorded_at: datetime | None = None) -> None:
self.rows.append(PluginMetric(source_module=source_module, resource_name=resource_name,
metric_name=metric_name, value=float(value),
recorded_at=recorded_at))
async def record(self, session: AsyncSession) -> None:
rows, self.rows = self.rows, []
await record_metrics(session, rows)
def _in_window(w: MaintenanceWindow, source_module: str, resource_name: str) -> bool:
if w.scope_source is None:
return True
return w.scope_source == source_module and w.scope_resource in (None, resource_name)
MUTED = "notification muted: maintenance window"
RELEASED = "notified when the window ended"
def _muted_by(windows, rule: AlertRule) -> str | None:
"""The note an event carries when a maintenance window holds back its
notification, or None when no window covers the rule."""
w = next((w for w in windows if _in_window(w, rule.source_module, rule.resource_name)), None)
return f"{MUTED} {w.name}" if w else None
# Notification and action tasks in flight. Held here so the event loop's weak
# references are not the only ones (a dropped task is silently never run).
_background: set[asyncio.Task] = set()
_AFTER_COMMIT = "steward_alert_after_commit"
def _spawn(coro) -> None:
task = asyncio.create_task(coro)
_background.add(task)
task.add_done_callback(_background.discard)
def _after_commit(session: AsyncSession, fn, *args) -> None:
"""Run fn(app, *args) once the session's transaction commits, and never if
it rolls back: a notification or a playbook run must describe what was
actually stored."""
if _app is None:
return
info = session.info
if _AFTER_COMMIT not in info:
info[_AFTER_COMMIT] = []
app = _app
def _committed(_sync_session) -> None:
jobs, info[_AFTER_COMMIT] = info[_AFTER_COMMIT], []
for job_fn, job_args in jobs:
_spawn(job_fn(app, *job_args))
def _rolled_back(_sync_session) -> None:
info[_AFTER_COMMIT] = []
sa_event.listen(session.sync_session, "after_commit", _committed)
sa_event.listen(session.sync_session, "after_rollback", _rolled_back)
info[_AFTER_COMMIT].append((fn, args))
async def record_metrics(session: AsyncSession, rows: list[PluginMetric], phases=None) -> None:
"""Write metric rows and evaluate the alert rules that watch them.
Every ingest path comes through here, so a rule on any metric Steward
records can fire. Must be called inside an active transaction:
async with session.begin():
await record_metrics(session, rows)
Maintenance windows, rules and their states are read once per batch, not
once per row. Each rule sees its key's samples oldest first, so a backlog
(an agent catching up after an outage) counts consecutive checks as they
happened. A maintenance window holds back notifications and actions, not
evaluation: the state still moves, and the event says it was muted.
Notifications and actions start only once the transaction commits.
`phases`, when given, is marked after each step (flush, rules, evaluate)
so a slow caller can say which one its time went to.
"""
mark = phases.mark if phases is not None else (lambda _name: None)
if not rows:
return
now = datetime.now(timezone.utc)
for row in rows:
if row.recorded_at is None:
row.recorded_at = now
session.add_all(rows)
await session.flush()
mark("flush")
by_key: dict[tuple[str, str, str], list[PluginMetric]] = {}
for row in rows:
by_key.setdefault((row.source_module, row.resource_name, row.metric_name), []).append(row)
sources = {k[0] for k in by_key}
metric_names = {k[2] for k in by_key}
rules = (await session.execute(
select(AlertRule).where(
AlertRule.source_module.in_(sources),
AlertRule.metric_name.in_(metric_names),
AlertRule.enabled.is_(True),
)
)).scalars().all()
rules = [r for r in rules if (r.source_module, r.resource_name, r.metric_name) in by_key]
if not rules:
mark("rules")
return
windows = (await session.execute(
select(MaintenanceWindow).where(
MaintenanceWindow.start_at <= now, MaintenanceWindow.end_at >= now)
)).scalars().all()
states = {st.rule_id: st for st in (await session.execute(
select(AlertState).where(AlertState.rule_id.in_([r.id for r in rules]))
)).scalars()}
mark("rules")
for rule in rules:
alert_state = states.get(rule.id)
if alert_state is None:
logger.warning("No alert_state row for rule %s, skipping", rule.id)
continue
samples = sorted(by_key[(rule.source_module, rule.resource_name, rule.metric_name)],
key=lambda r: r.recorded_at)
muted = _muted_by(windows, rule)
resumed = _track_samples(session, rule, alert_state, samples, now, muted)
if resumed and rule.notify_no_data and not muted:
event_id, value, note = resumed
_after_commit(session, _dispatch_notification, "data_resumed", rule, value,
event_id, note)
for sample in samples:
notifications = await _evaluate_rule(session, rule, alert_state, sample.value,
sample.recorded_at, note=muted)
if muted:
continue
for notif_type, event_id in notifications:
_after_commit(session, _dispatch_notification, notif_type, rule, sample.value,
event_id)
# Admin-configured Ansible action runs only on transition-to-firing.
if notif_type == "firing" and rule.ansible_action:
_after_commit(session, _run_ansible_action, rule, sample.value, event_id)
mark("evaluate")
# A series is silent once it has gone this long without a sample, or three of
# its usual gaps if that is longer. Until its cadence is known (fewer than two
# samples seen), it gets an hour: a monitor may check only every ten minutes.
NO_DATA_FLOOR_S = 300.0
NO_DATA_GAPS = 3
NO_DATA_UNKNOWN_S = 3600.0
def next_interval(interval: float | None, gap: float) -> float:
"""A series' usual gap between samples, updated with one more gap.
A smoothed average, so one late sample barely moves it. A gap longer than
the silence threshold counts only as that threshold: an outage is not the
series' cadence. A real change of cadence still gets learned, a step at a
time (each step at most 1.5x).
"""
gap = max(0.0, gap)
if interval is None or interval <= 0:
return gap
return 0.75 * interval + 0.25 * min(gap, NO_DATA_GAPS * interval)
def no_data_after(interval: float | None) -> float:
"""Seconds without a sample before a series counts as silent."""
if not interval:
return NO_DATA_UNKNOWN_S
return max(NO_DATA_FLOOR_S, NO_DATA_GAPS * interval)
def silent_since(last_sample_at: datetime | None, interval: float | None,
watching_since: datetime, now: datetime) -> datetime | None:
"""When a series went silent, or None while it is still reporting.
A series that has never had a sample counts from when the rule started
watching it (created, changed or re-enabled).
"""
last = last_sample_at or watching_since
limit = timedelta(seconds=no_data_after(interval))
return last + limit if now - last > limit else None
def _track_samples(session: AsyncSession, rule: AlertRule, state: AlertState,
samples: list[PluginMetric], now: datetime, muted: str | None = None
) -> tuple[str, float, str] | None:
"""Note a rule's new samples (oldest first) for silence tracking. When the
series had been marked no_data, clear it and record a resume event,
returned as (event_id, value, note) for the caller to notify. `muted` is
added to the event's note when a maintenance window holds it back."""
for sample in samples:
if state.last_sample_at is not None:
if sample.recorded_at <= state.last_sample_at:
continue # late or duplicate: not a gap
gap = (sample.recorded_at - state.last_sample_at).total_seconds()
state.sample_interval_s = next_interval(state.sample_interval_s, gap)
state.last_sample_at = sample.recorded_at
if state.no_data_since is None or not samples:
return None
note = f"data resumed after {human_duration((now - state.no_data_since).total_seconds())} silent"
value = samples[-1].value
event_id = _add_event(session, rule.id, "no_data", state.state.value, value, now,
note=f"{note}; {muted}" if muted else note)
state.no_data_since = None
return event_id, value, note
def _is_breached(value: float, operator: AlertOperator, threshold: float) -> bool:
op = operator.value
if op == ">":
return value > threshold
if op == "<":
return value < threshold
if op == ">=":
return value >= threshold
if op == "<=":
return value <= threshold
if op == "==":
return value == threshold
if op == "!=":
return value != threshold
return False
@dataclass(frozen=True)
class Step:
"""One sample's effect on an alert: the state after it, the two run
counters, and the event to record ("firing" / "resolved") if any."""
state: AlertStateEnum
fail_count: int
ok_count: int
event: str | None = None
def next_step(state: AlertStateEnum, fail_count: int, ok_count: int, breached: bool,
fail_required: int, ok_required: int) -> Step:
"""The alert state machine, as a pure function of one sample.
inactive → pending → firing when `fail_required` breaching checks run in a
row; a non-breaching check while pending goes back to inactive.
firing and acknowledged resolve (to inactive, with a resolved event) only
after `ok_required` non-breaching checks in a row; a breaching check
resets that run. An acknowledgement holds while the alert is still
breached: only a resolve clears it.
"""
fail_required, ok_required = max(1, fail_required), max(1, ok_required)
S = AlertStateEnum
if state in (S.firing, S.acknowledged):
if breached:
return Step(state, fail_count + 1, 0)
if ok_count + 1 >= ok_required:
return Step(S.inactive, 0, 0, "resolved")
return Step(state, fail_count, ok_count + 1)
# inactive, pending (and the transient resolved, read as inactive)
if not breached:
return Step(S.inactive, 0, 0)
fails = fail_count + 1 if state == S.pending else 1
if fails >= fail_required:
return Step(S.firing, fails, 0, "firing")
return Step(S.pending, fails, 0)
async def _evaluate_rule(
session: AsyncSession,
rule: AlertRule,
state: AlertState,
value: float,
now: datetime,
note: str | None = None,
) -> list[tuple[str, str]]:
"""Apply one sample to a rule's state. Returns [(notif_type, event_id)];
an event it records carries `note`."""
from_state = state.state
step = next_step(from_state, state.consecutive_failure_count, state.consecutive_ok_count,
_is_breached(value, rule.operator, rule.threshold),
rule.consecutive_failures_required, rule.consecutive_ok_required)
state.consecutive_failure_count = step.fail_count
state.consecutive_ok_count = step.ok_count
notifications: list[tuple[str, str]] = []
if step.state != from_state:
state.state = step.state
state.last_transition_at = now
if step.state == AlertStateEnum.inactive:
state.acknowledged_by = None
state.acknowledged_at = None
if step.event:
event_id = _add_event(session, rule.id, from_state.value, step.event, value, now,
note=note)
notifications.append((step.event, event_id))
await session.flush()
return notifications
async def reset_rule_state(session: AsyncSession, rule: AlertRule, note: str) -> None:
"""Put a rule's alert back to inactive because the rule itself changed
(what it watches, its threshold, or it was disabled or re-enabled), and
start its silence watch over. An alert that was
firing or acknowledged gets a resolved event carrying `note`; nobody is
notified, since nothing about the watched resource changed."""
state = (await session.execute(
select(AlertState).where(AlertState.rule_id == rule.id))).scalar_one_or_none()
if state is None:
return
now = datetime.now(timezone.utc)
if state.state in (AlertStateEnum.firing, AlertStateEnum.acknowledged):
_add_event(session, rule.id, state.state.value, "resolved", None, now, note=note)
# The watch starts over now: silence is measured from here, against the
# cadence of whatever the rule watches from now on.
state.last_transition_at = now
state.last_sample_at = None
state.sample_interval_s = None
state.no_data_since = None
state.state = AlertStateEnum.inactive
state.consecutive_failure_count = 0
state.consecutive_ok_count = 0
state.acknowledged_by = None
state.acknowledged_at = None
def _add_event(
session: AsyncSession,
rule_id: str,
from_state: str,
to_state: str,
value: float | None,
now: datetime,
note: str | None = None,
) -> str:
"""Add an AlertEvent row and return its ID."""
event_id = str(uuid.uuid4())
event = AlertEvent(
id=event_id,
rule_id=rule_id,
from_state=from_state,
to_state=to_state,
metric_value=value,
transitioned_at=now,
note=note,
)
session.add(event)
return event_id
async def _dispatch_notification(
app: "Quart",
notif_type: str,
rule: AlertRule,
value: float | None,
event_id: str,
note: str | None = None,
) -> None:
"""Run after the transaction commits. Sends notifications and updates the event row."""
from steward.core.notifications import dispatch_notifications
alert_data = {
"rule_name": rule.name,
"state": notif_type.upper(),
"metric": rule.metric_name,
"value": value,
"threshold": rule.threshold,
"resource": rule.resource_name,
"source_module": rule.source_module,
"note": note,
"timestamp": datetime.now(timezone.utc).isoformat(),
}
smtp_cfg = app.config.get("SMTP", {})
webhook_cfg = app.config.get("WEBHOOK", {})
results = await dispatch_notifications(smtp_cfg, webhook_cfg, alert_data)
# Update event row with delivery results in a new transaction
async with app.db_sessionmaker() as db:
async with db.begin():
event_result = await db.execute(
select(AlertEvent).where(AlertEvent.id == event_id)
)
event = event_result.scalar_one_or_none()
if event:
email_r = results.get("email")
if email_r:
event.email_sent = email_r["sent"]
event.email_error = email_r.get("error")
webhook_r = results.get("webhook")
if webhook_r:
event.webhook_sent = webhook_r["sent"]
event.webhook_error = webhook_r.get("error")
async def _run_ansible_action(
app: "Quart",
rule: AlertRule,
value: float,
event_id: str,
) -> None:
"""Run the rule's configured Ansible playbook (system-triggered).
Starts after the evaluation transaction commits. Goes through
runner.trigger_run like every other run path, so the playbook and the
inventory must be ones the source lists (ansible/guards.py). The firing
event links to the run, or says why the action did not start.
"""
from steward.ansible.runner import IN_FLIGHT, trigger_run
from steward.models.ansible import AnsibleRun
if rule.id in _actions_starting:
await _note_event(app, event_id, "Ansible action skipped: an earlier "
"firing's action was still starting")
return
async with app.db_sessionmaker() as db:
busy = (await db.execute(
select(AnsibleRun.id)
.join(AlertEvent, AlertEvent.ansible_run_id == AnsibleRun.id)
.where(AlertEvent.rule_id == rule.id, AnsibleRun.status.in_(IN_FLIGHT))
.limit(1))).scalar_one_or_none()
if busy:
# One action run at a time per rule (#5158): a re-firing while the
# last one is still going would run the same fix over it.
await _note_event(app, event_id, f"Ansible action skipped: run {busy} "
"from an earlier firing was still going")
return
_actions_starting.add(rule.id)
try:
await _start_ansible_action(app, rule, value, event_id, trigger_run)
finally:
_actions_starting.discard(rule.id)
# Rules whose action is between the in-flight check and its run being linked
# to the event, so two firings that close together can't both start one.
_actions_starting: set[str] = set()
async def _note_event(app: "Quart", event_id: str, why: str) -> None:
async with app.db_sessionmaker() as db:
async with db.begin():
ev = (await db.execute(
select(AlertEvent).where(AlertEvent.id == event_id))).scalar_one_or_none()
if ev is not None:
ev.note = f"{ev.note}; {why}" if ev.note else why
async def _start_ansible_action(app, rule, value, event_id, trigger_run) -> None:
action = rule.ansible_action or {}
playbook = action.get("playbook") or ""
inventory = action.get("inventory") or ""
source_name = action.get("source") or ""
# One JSON extra-vars file; the firing's own vars win over the action's.
params: dict = {
"extra_vars_map": {**action_vars(action.get("extra_vars")),
**alert_extra_vars(rule, value)},
}
if action.get("limit"):
params["limit"] = action["limit"]
if action.get("tags"):
params["tags"] = action["tags"]
if action.get("check"):
params["check"] = True
scope = inventory if inventory.startswith("steward:") else f"repo:{source_name}:{inventory}"
if not playbook or not inventory:
run, err = None, "the action has no playbook or inventory"
else:
try:
run, _source, err = await trigger_run(
app, source_name=source_name, playbook_path=playbook,
inventory_scope=scope, params=params, triggered_by=None)
except Exception as exc:
logger.exception("Ansible action for rule %r failed to start", rule.name)
run, err = None, str(exc)
if err:
logger.error("Ansible action for rule %r not started: %s", rule.name, err)
if run is None:
await _note_event(app, event_id, f"Ansible action not started: {err}")
return
async with app.db_sessionmaker() as db:
async with db.begin():
ev = (await db.execute(
select(AlertEvent).where(AlertEvent.id == event_id))).scalar_one_or_none()
if ev is not None:
ev.ansible_run_id = run.id
async def check_silence(app: "Quart") -> None:
"""Mark the enabled rules whose series has gone silent (no_data).
Run every minute by the core scheduler. A rule is silent once its series
has had no sample for no_data_after(its usual gap); one that never had a
sample counts from when the rule started watching. The mark sits beside
the state, so a firing alert that goes silent stays firing. Each silence
is recorded once, as an event, and notified once (rule.notify_no_data,
outside maintenance windows), after the transaction commits.
"""
now = datetime.now(timezone.utc)
notify: list[tuple[AlertRule, str, str]] = []
async with app.db_sessionmaker() as session:
async with session.begin():
rows = (await session.execute(
select(AlertState, AlertRule)
.join(AlertRule, AlertState.rule_id == AlertRule.id)
.where(AlertRule.enabled.is_(True), AlertState.no_data_since.is_(None))
)).all()
if not rows:
return
windows = (await session.execute(
select(MaintenanceWindow).where(
MaintenanceWindow.start_at <= now, MaintenanceWindow.end_at >= now)
)).scalars().all()
for state, rule in rows:
watching_since = max(rule.created_at, state.last_transition_at)
since = silent_since(state.last_sample_at, state.sample_interval_s,
watching_since, now)
if since is None:
continue
state.no_data_since = since
if state.last_sample_at is None:
note = (f"no sample yet, {human_duration((now - watching_since).total_seconds())}"
" after the rule started watching")
else:
note = f"no sample for {human_duration((now - state.last_sample_at).total_seconds())}"
if state.sample_interval_s:
note += f" (usually every {human_duration(state.sample_interval_s)})"
muted = _muted_by(windows, rule)
event_id = _add_event(session, rule.id, state.state.value, "no_data", None,
now, note=f"{note}; {muted}" if muted else note)
if rule.notify_no_data and not muted:
notify.append((rule, event_id, note))
for rule, event_id, note in notify:
_spawn(_dispatch_notification(app, "no_data", rule, None, event_id, note))
async def notify_after_maintenance(app: "Quart") -> None:
"""Notify the alerts that started firing inside a maintenance window and
are still firing now that no window covers them, and run their actions:
a window delays what it mutes, it does not discard it. Run every minute
by the core scheduler; each muted firing is released once."""
now = datetime.now(timezone.utc)
release: list[tuple[AlertRule, str, float | None]] = []
async with app.db_sessionmaker() as session:
async with session.begin():
rows = (await session.execute(
select(AlertState, AlertRule)
.join(AlertRule, AlertState.rule_id == AlertRule.id)
.where(AlertRule.enabled.is_(True), AlertState.state == AlertStateEnum.firing)
)).all()
if not rows:
return
windows = (await session.execute(
select(MaintenanceWindow).where(
MaintenanceWindow.start_at <= now, MaintenanceWindow.end_at >= now)
)).scalars().all()
for state, rule in rows:
if _muted_by(windows, rule):
continue
fired = (await session.execute(
select(AlertEvent)
.where(AlertEvent.rule_id == rule.id, AlertEvent.to_state == "firing")
.order_by(AlertEvent.transitioned_at.desc()).limit(1)
)).scalar_one_or_none()
note = (fired.note or "") if fired else ""
if MUTED not in note or RELEASED in note:
continue
fired.note = f"{note}; {RELEASED}"
release.append((rule, fired.id, fired.metric_value))
for rule, event_id, value in release:
_spawn(_dispatch_notification(app, "firing", rule, value, event_id))
if rule.ansible_action:
_spawn(_run_ansible_action(app, rule, value, event_id))