Show live progress while pruning volumes, and ask first (0.62.0)

The volume prune gets the same treatment as the image prune in 0.61.0:
the candidates are listed and removed one by one in the background, and
the Volumes page shows a progress bar (x / y, the volume being removed,
failures) followed by a toast with the space freed.

The button also used to delete without asking, and a bare docker volume
prune only removes anonymous volumes on Engine 23+ with no way to include
named ones. It now opens a confirmation dialog with an explicit -a option
that warns it also takes the data of every stack that is down.

- Candidates: volumes no container (running or stopped) mounts, local
  scope only, and anonymous (com.docker.volume.anonymous) unless -a.
  Volumes from pre-23 daemons carry no such label, so they only go with
  -a, which errs on the side of keeping data.
- Removed without force, so a volume mounted since the listing is
  refused; one refusal does not stop the rest.
- No closing daemon prune: nothing is left over, and on a pre-23 daemon an
  unfiltered one would delete named volumes too.
- Freed space is the sum of the deleted volumes' sizes (volumes share no
  data), from the size cache, which is invalidated afterwards.
- POST /api/volumes/prune takes all= and background=; without background
  it still waits and returns {VolumesDeleted, SpaceReclaimed}.
  GET /api/volumes/prune-status is admin-only.
- volume_sizes() ("Compute sizes") now uses the long-timeout client; it
  walks every volume and could hit the same 60s limit.

The progress machinery moved into services/prune_job.py (PruneJob,
PrunePlan) and, on the frontend, the usePruneJob hook and PruneProgress
component, shared by both pages. The status now carries a phase
(preparing / removing / finishing) so the parts without a count say what
they are doing.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

backend/tests/test_volume_prune.py

@@ -0,0 +1,189 @@
+"""Volume prune with visible progress, and an explicit -a.
+
+Same mechanism as the image prune (services/prune_job.py): the candidates are
+listed, removed one by one and the progress is published through
+/api/volumes/prune-status. On top of that the button used to call a bare
+``docker volume prune``, which on Engine 23+ only removes anonymous volumes and
+offered no way to include named ones.
+
+Pinned here: nothing a container mounts is touched, named volumes only go with
+-a, a refusal does not stop the rest, and the freed space is the sum of what
+was actually deleted.
+"""
+from __future__ import annotations
+
+import threading
+
+import pytest
+from docker.errors import APIError
+
+MB = 1024 * 1024
+ANON = {"com.docker.volume.anonymous": ""}
+ANON_ID = "3f1c" + "0" * 60
+
+
+class FakeApi:
+    def __init__(self):
+        self._volumes = [
+            {"Name": ANON_ID, "Labels": ANON, "Scope": "local"},
+            {"Name": "media_cache", "Labels": {"com.docker.compose.project": "media"}, "Scope": "local"},
+            {"Name": "old_data", "Labels": None, "Scope": "local"},
+            {"Name": "pg_data", "Labels": {}, "Scope": "local"},
+            {"Name": "cluster_vol", "Labels": {}, "Scope": "global"},
+        ]
+        # pg_data is mounted by a (possibly stopped) container.
+        self._containers = [
+            {"Mounts": [{"Type": "volume", "Name": "pg_data"}, {"Type": "bind", "Source": "/srv"}]}
+        ]
+        self.removed: list[str] = []
+        self.refuse: set[str] = set()
+        self.gate: threading.Event | None = None
+
+    def containers(self, all=False):
+        return self._containers
+
+    def volumes(self, filters=None):
+        return {"Volumes": list(self._volumes), "Warnings": None}
+
+    def remove_volume(self, name, force=False):
+        assert force is False
+        if self.gate:
+            self.gate.wait(5)
+        if name in self.refuse:
+            raise APIError(f"remove {name}: volume is in use")
+        self.removed.append(name)
+        self._volumes = [v for v in self._volumes if v["Name"] != name]
+
+
+class FakeClient:
+    def __init__(self, api):
+        self.api = api
+
+
+@pytest.fixture
+def svc(monkeypatch):
+    from services import volume_service
+
+    api = FakeApi()
+    client = FakeClient(api)
+
+    def short():
+        raise AssertionError("prune must not use the 60s client")
+
+    monkeypatch.setattr(volume_service, "get_client", short)
+    monkeypatch.setattr(volume_service, "get_long_client", lambda: client)
+    monkeypatch.setattr(
+        volume_service,
+        "volume_sizes",
+        lambda force=False: {ANON_ID: 5 * MB, "media_cache": 300 * MB, "old_data": None, "pg_data": 900 * MB},
+    )
+    yield volume_service, api
+    if volume_service._prune._lock.locked():
+        volume_service._prune._lock.release()
+
+
+def test_default_only_removes_unused_anonymous_volumes(svc):
+    volume_service, api = svc
+
+    result = volume_service.prune_volumes()
+
+    assert api.removed == [ANON_ID]
+    assert result == {"VolumesDeleted": [ANON_ID], "SpaceReclaimed": 5 * MB}
+
+
+def test_all_also_removes_named_but_never_mounted_or_cluster_volumes(svc):
+    volume_service, api = svc
+
+    result = volume_service.prune_volumes(all_unused=True)
+
+    assert set(api.removed) == {ANON_ID, "media_cache", "old_data"}
+    # A volume of unknown size counts as nothing rather than failing the sum.
+    assert result["SpaceReclaimed"] == 305 * MB
+    status = volume_service.prune_status()
+    assert (status["total"], status["done"], status["deleted"]) == (3, 3, 3)
+    assert status["reclaimed"] == 305 * MB and status["active"] is False
+
+
+def test_refused_volume_does_not_stop_the_rest(svc):
+    volume_service, api = svc
+    api.refuse.add("media_cache")
+
+    result = volume_service.prune_volumes(all_unused=True)
+
+    assert set(result["VolumesDeleted"]) == {ANON_ID, "old_data"}
+    status = volume_service.prune_status()
+    assert status["failed"] == 1 and status["errors"][0].startswith("media_cache: ")
+    assert result["SpaceReclaimed"] == 5 * MB
+
+
+def test_unknown_sizes_leave_reclaimed_unknown(svc, monkeypatch):
+    volume_service, _ = svc
+
+    def broken(force=False):
+        raise RuntimeError("df failed")
+
+    monkeypatch.setattr(volume_service, "volume_sizes", broken)
+    result = volume_service.prune_volumes(all_unused=True)
+
+    assert len(result["VolumesDeleted"]) == 3
+    assert volume_service.prune_status()["reclaimed"] is None
+
+
+def test_anonymous_volumes_are_labelled_by_short_id(svc):
+    volume_service, api = svc
+    api.gate = threading.Event()
+
+    finished = threading.Event()
+
+    volume_service.start_prune(all_unused=False, on_done=lambda r: finished.set())
+    for _ in range(100):
+        status = volume_service.prune_status()
+        if status["current"]:
+            break
+        threading.Event().wait(0.02)
+    api.gate.set()
+    assert finished.wait(5)
+    assert status["current"] == ANON_ID[:12]
+
+
+def test_endpoint_background_then_poll(svc, as_admin):
+    r = as_admin.post("/api/volumes/prune", params={"all": True, "background": True})
+    assert r.status_code == 202 and r.json()["total"] == 3
+
+    for _ in range(100):
+        s = as_admin.get("/api/volumes/prune-status").json()
+        if not s["active"]:
+            break
+        threading.Event().wait(0.02)
+    assert s["deleted"] == 3 and s["reclaimed"] == 305 * MB
+
+
+def test_endpoint_waits_by_default_and_is_audited(svc, as_admin):
+    from sqlmodel import Session, select
+
+    from database import engine
+    from models.audit import AuditLog
+
+    r = as_admin.post("/api/volumes/prune")
+    assert r.status_code == 200
+    assert r.json()["VolumesDeleted"] == [ANON_ID]
+
+    with Session(engine) as session:
+        row = session.exec(
+            select(AuditLog).where(AuditLog.action == "volume.prune").order_by(AuditLog.id.desc())
+        ).first()
+    assert row.detail == f"all=False deleted=['{ANON_ID}']"
+
+
+def test_endpoint_rejects_a_second_prune(svc, as_admin):
+    volume_service, _ = svc
+    volume_service._prune._lock.acquire()
+    try:
+        assert as_admin.post("/api/volumes/prune").status_code == 409
+    finally:
+        volume_service._prune._lock.release()
+
+
+def test_prune_is_admin_only(svc, as_user):
+    assert as_user.post("/api/volumes/prune").status_code == 403
+    assert as_user.get("/api/volumes/prune-status").status_code == 403