feat(docker): Docker disk is recorded over time per host, the Disk page shows each host's growth and folds images under their repository, and the overview has one disk line per host (#5304–#5306)

- #5304 "Docker disk totals recorded over time per host, with a growth chart and alertable metrics"
- #5305 "Disk page: images grouped by repository, versions folded under it"
- #5306 "Docker overview: one disk line per host linking to the Disk page"

Each `docker system df` report is now also recorded as metrics, with the host
as the resource: disk_total_bytes, its parts, and disk_reclaimable_bytes. An
alert rule can watch them. The Disk page starts with the hosts side by side,
showing how much each grew over the selected range with a line of it, then
gives each host its own section. An image's versions fold under its
repository, which is charged only for the layers its versions don't share.

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

tests/plugins/docker/test_docker_page.py

@@ -206,27 +206,55 @@ async def test_the_docker_page_has_a_filter_bar_the_rows_read(app):
     assert 'hx-include="#docker-filters"' in page and "change from:#docker-filters" in page
 
 
-async def test_the_disk_page_explains_its_terms_and_names_untagged_images(app):
-    """#5212: no unexplained jargon, no "<none>" rows, and a capped list says so."""
-    summary = {"images_total": 312, "images_active": 40, "images_size": "40 GiB",
-               "images_reclaimable": "12 GiB", "layers_size": "30 GiB", "containers_count": 9,
-               "containers_size": "1.2 GiB", "volumes_count": 4, "volumes_size": "3 GiB",
-               "build_cache_size": "2 GiB"}
-    images = [{"repo_tag": "nginx:1", "image_id": "aaaaaaaaaaaa", "size": "180 MiB", "shared": "70 MiB",
-               "containers": 2, "reclaimable": False},
-              {"repo_tag": None, "image_id": "bbbbbbbbbbbb", "size": "700 MiB", "shared": "0 B",
-               "containers": 0, "reclaimable": True}]
+async def test_the_disk_page_explains_its_terms_and_folds_images_by_repository(app):
+    """#5212, #5305: no unexplained jargon, no "<none>" rows, a capped list says
+    so; an image's versions sit under its repository."""
+    from quart import session
+    from plugins.docker.disk_view import group_images
+    gib = 1 << 30
+    summary = NS(images_total=312, images_active=40, images_size=40 * gib, images_reclaimable=12 * gib,
+                 containers_count=9, containers_size=gib, volumes_count=4, volumes_size=3 * gib,
+                 build_cache_size=2 * gib)
+    repos = group_images([
+        {"repo_tag": "nginx:1.27", "image_id": "sha256:" + "a" * 64, "size": 180 << 20, "shared_size": 70 << 20, "containers": 2},
+        {"repo_tag": "nginx:1.25", "image_id": "sha256:" + "c" * 64, "size": 170 << 20, "shared_size": 70 << 20, "containers": 0},
+        {"repo_tag": "<none>", "image_id": "sha256:" + "b" * 64, "size": 700 << 20, "shared_size": 0, "containers": 0}])
     group = {"host_id": "h1", "host_name": "nas", "as_of": NOW - timedelta(minutes=2), "summary": summary,
-             "stopped": 1, "images": images, "has_target": True, "images_capped": True}
+             "total": 46 * gib, "stopped": 1, "repos": repos, "images_listed": 3, "has_target": True,
+             "images_capped": True}
     async with app.test_request_context("/plugins/docker/disk"):
-        page = await render_plugin_template(app, "docker", "docker/disk.html",
-                                            host_groups=[group], ansible_available=True)
-    assert "untagged</span> bbbbbbbbbbbb" in page and "&lt;none&gt;" not in page
-    assert "The 2 largest of 312 images" in page and "as of <time" in page
-    assert "Writable layers" not in page and "Container files" in page
-    assert "held by images no container uses" in page and "safe to clear" in page
-    assert "Shared with other images" in page and "2 containers" in page and ">nothing<" in page
-    assert "dangling" not in page
+        session["user_role"] = "admin"
+        page = await render_plugin_template(app, "docker", "docker/disk.html", host_groups=[group],
+                                            ansible_available=True, current_range="7d")
+    page = re.sub(r">\s+<", "><", " ".join(page.split()))
+    assert 'hx-get="/plugins/docker/disk/hosts"' in page and 'id="time-range"' in page
+    assert 'id="host-h1"' in page and "as of <time" in page
+    assert '<span class="tone-muted">untagged</span>' in page and "&lt;none&gt;" not in page
+    assert "the 3 largest of 312 images" in page
+    assert '<span class="mono">nginx</span>' in page and ">1.27<" in page and ">1.25<" in page
+    assert "(1 unused)" in page and ">2 containers<" in page and ">nothing<" in page
+    assert "Container files" in page and "held by images no container uses" in page and "safe to clear" in page
+    assert page.count('action="/plugins/docker/disk/h1/prune"') == 3
+    assert "Writable layers" not in page and "dangling" not in page
+
+
+async def test_the_disk_hosts_say_how_much_each_grew(app):
+    gib = 1 << 30
+    rows = [{"host_id": "h1", "host_name": "docker02", "total": 42 * gib, "reclaimable": 5 * gib,
+             "parts": {"disk_images_bytes": 30 * gib, "disk_volumes_bytes": 10 * gib,
+                       "disk_containers_bytes": 2 * gib, "disk_build_cache_bytes": 0},
+             "growth": {"change": 6 * gib, "since": NOW - timedelta(days=7), "from": 36 * gib, "to": 42 * gib,
+                        "pct": 16.7}, "spark": "<svg></svg>"},
+            {"host_id": "h2", "host_name": "util01", "total": gib, "reclaimable": 0,
+             "parts": {"disk_images_bytes": gib, "disk_volumes_bytes": 0, "disk_containers_bytes": 0,
+                       "disk_build_cache_bytes": 0}, "growth": None, "spark": "<svg></svg>"}]
+    async with app.test_request_context("/plugins/docker/disk/hosts"):
+        page = await render_plugin_template(app, "docker", "docker/_disk_hosts.html", rows=rows, range_key="7d")
+    page = re.sub(r">\s+<", "><", " ".join(page.split()))
+    assert '<a href="#host-h1">docker02</a>' in page and "<strong>42.0 GiB</strong>" in page
+    assert 'class="tone-warn"' in page and ">+6.0 GiB<" in page and "Change (7d)" in page
+    assert "growth shows once there are two readings" in page
+    assert not hex_colours(page), hex_colours(page)
 
 
 def _widget_svc(name, state="healthy", running=1, desired=1, hosts=("VDNT-Docker02",), **kw):