feat(host_agent): a group's updates and reboots on a weekly cadence, one host at a time (#5768)

#5768 "A maintenance cadence: a group's updates and reboots, one host at a
time, on a schedule". A plan names an inventory group, a weekday and time
in a time zone, a window and a reboot policy (only when required by
default). At its slot a run takes the group's hosts in order and gives each
a #5767 maintenance job. The next host starts only when the last is back in
service: its agent is posting and, for a swarm node, the node is active and
every replicated service is at its replicas. A failure stops the run, and
no host is started once the window has passed. A host's latest failure
shows as host_agent/<host>/maintenance_failed, for an ordinary alert rule.
The page is Hosts → Maintenance.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/integration/test_host_maintenance_cadence.py

@@ -0,0 +1,134 @@
+"""Integration (#5768): a plan updates its group's hosts one at a time; the
+second starts only once the first is back, and a failure stops the run and
+flags the host for an alert rule.
+
+The plugin's cadence and models are reached through the module the app loaded
+(see test_docker_disk_page): importing the plugin's models again raises
+"Table already defined"."""
+from __future__ import annotations
+
+import asyncio
+import hashlib
+import importlib
+import os
+import uuid
+from datetime import datetime, timezone
+
+import pytest
+
+pytestmark = pytest.mark.integration
+
+
+def _app():
+    if not os.environ.get("STEWARD_DATABASE_URL"):
+        pytest.skip("needs Postgres")
+    from steward.app import create_app
+    return create_app(testing=False)
+
+
+def _ha(sub):
+    from steward.core.plugin_manager import get_loaded_plugin_modules
+    loaded = get_loaded_plugin_modules().get("host_agent")
+    base = loaded.__name__ if loaded is not None else "plugins.host_agent"
+    return importlib.import_module(f"{base}.{sub}")
+
+
+async def _seed(app):
+    from sqlalchemy import text
+    from steward.models.ansible_inventory import AnsibleGroup, AnsibleTarget
+    from steward.models.hosts import Host
+    from steward.models.users import User
+    tag = uuid.uuid4().hex[:8]
+    out = {"tokens": {}, "hosts": {}}
+    async with app.db_sessionmaker() as s:
+        async with s.begin():
+            user = User(username=f"cad-{tag}", email=f"cad-{tag}@test", password_hash="x")
+            group = AnsibleGroup(name=f"cad-{tag}")
+            s.add_all([user, group])
+            await s.flush()
+            for n in ("a", "b"):
+                host = Host(name=f"cad-{n}-{tag}", address="10.9.9.6")
+                s.add(host)
+                await s.flush()
+                target = AnsibleTarget(name=f"cad-{n}-{tag}", address="10.9.9.6", host_id=host.id)
+                target.groups = [group]
+                s.add(target)
+                token = f"tok-{n}-{tag}-{uuid.uuid4().hex}"
+                await s.execute(text(
+                    "INSERT INTO host_agent_registrations "
+                    "(id, host_id, token_hash, token_created_at, last_seen_at, maint_helper, "
+                    " created_at, updated_at) VALUES (:id, :h, :hash, now(), now(), true, now(), now())"),
+                    {"id": str(uuid.uuid4()), "h": host.id,
+                     "hash": hashlib.sha256(token.encode()).hexdigest()})
+                out["tokens"][n], out["hosts"][n] = token, host
+            plan_id = str(uuid.uuid4())
+            await s.execute(text(
+                "INSERT INTO host_maintenance_plans (id, name, group_id, weekday, at_time, time_zone, "
+                " window_minutes, reboot_policy, enabled, created_by, created_at) "
+                "VALUES (:id, :name, :g, 6, '03:00', 'UTC', 240, 'if_required', true, :u, now())"),
+                {"id": plan_id, "name": f"plan-{tag}", "g": group.id, "u": user.id})
+    out["plan_id"] = plan_id
+    return out
+
+
+async def _post(app, token, events=()):
+    resp = await app.test_client().post(
+        "/plugins/host_agent/ingest",
+        json={"samples": [{"ts": datetime.now(timezone.utc).isoformat(), "cpu_pct": 1.0}],
+              "events": list(events)},
+        headers={"Authorization": f"Bearer {token}"})
+    assert resp.status_code == 200, await resp.get_data(as_text=True)
+    return (await resp.get_json()).get("maintenance", [])
+
+
+async def _tick(app):
+    cadence = _ha("cadence")
+    async with app.db_sessionmaker() as s:
+        async with s.begin():
+            await cadence.tick(s, datetime.now(timezone.utc))
+            return await cadence.failed_hosts(s, datetime.now(timezone.utc))
+
+
+async def _run(app, plan_id):
+    from sqlalchemy import text
+    async with app.db_sessionmaker() as s:
+        return (await s.execute(text(
+            "SELECT state, position, detail FROM host_maintenance_runs WHERE plan_id = :p"),
+            {"p": plan_id})).one()
+
+
+def test_hosts_go_one_at_a_time_and_a_failure_stops_the_run():
+    app = _app()
+
+    async def _go():
+        seed = await _seed(app)
+        cadence, models = _ha("cadence"), _ha("models")
+        async with app.db_sessionmaker() as s:
+            async with s.begin():
+                plan = await s.get(models.HostMaintenancePlan, seed["plan_id"])
+                await cadence.start_run(s, plan, datetime.now(timezone.utc), manual=True)
+        await _tick(app)
+
+        # Only the first host (by name) has a job; the second waits.
+        ta, tb = seed["tokens"]["a"], seed["tokens"]["b"]
+        assert await _post(app, tb) == []
+        (step,) = await _post(app, ta)
+        assert step["action"] == "update"
+        done = {"kind": "maintenance", "id": step["id"], "action": "update", "state": "done",
+                "ok": True, "packages": 2, "reboot_required": False}
+        await _post(app, ta, [done])
+
+        # Back in service (posting, not a swarm node): the next host starts.
+        await _tick(app)
+        assert (await _run(app, seed["plan_id"]))[:2] == ("running", 1)
+        (step_b,) = await _post(app, tb)
+        failed = {"kind": "maintenance", "id": step_b["id"], "action": "update",
+                  "state": "failed", "ok": False, "detail": "dpkg was interrupted"}
+        await _post(app, tb, [failed])
+
+        flags = await _tick(app)
+        state, _, detail = await _run(app, seed["plan_id"])
+        assert state == "failed" and seed["hosts"]["b"].name in detail and "dpkg" in detail
+        assert flags[seed["hosts"]["b"].name] == 1.0 and flags[seed["hosts"]["a"].name] == 0.0
+
+    asyncio.run(_go())