feat(snmp): NAS presets for Synology and Asustor, reading every disk and volume (#5985, #5986)

A preset can now read a vendor's tables: one row per disk, volume, fan or
sensor. The scheduled poll discovers the rows by walking the device: on its
first poll, after a save, and then hourly, and only while it answers. Each row
becomes readings named by the device's own labels ("Disk 1 status"). Only the
columns a row answered are asked for.

A vendor status, whether a code (Synology) or a word (Asustor), is a state
reading. It is stored as a level (0 OK, 1 busy, 2 warning, 3 failed), so one
alert rule covers any vendor, and shown in the device's own word.

- Synology: system, power and fan status and temperature; per disk: status,
  health, temperature and bad sectors; per volume: RAID state (scrubbing,
  parity check, rebuild, degraded), free space and size.
- Asustor: per disk: status, SMART and temperature; per volume: status, free
  space and size; CPU and system temperature, free memory and fans.
  From ADM's ASUSTOR-DISK-MIB and ASUSTOR-SYSTEM-MIB.
- Linux server: plus each physical disk's 1-minute busy % (UCD-DISKIO-MIB).

Migration snmp_002_table_rows adds tables, tables_at and texts to
snmp_devices. Milestone 530.

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

tests/plugins/snmp/test_readings.py

@@ -1,8 +1,9 @@
 """What an SNMP device is asked for and how each answer reads (milestone 491)."""
 import pytest
 
-from plugins.snmp.readings import (device_readings, format_value, interface_readings, parse_custom,
-                                   parse_interfaces, stored_unit)
+from plugins.snmp.readings import (TABLES, Column, Reading, Table, device_readings, format_value,
+                                   interface_readings, parse_custom, parse_interfaces, reading_text, state_of,
+                                   stored_unit, table_readings, tables_for)
 
 
 def test_interface_numbers_read_as_a_list():
@@ -64,6 +65,72 @@ def test_presets_come_in_order_and_names_may_not_repeat():
     ("if_status", 99, "code 99"),
     ("number", 41.25, "41.25"),
     ("number", None, "—"),
+    ("state", 2, "Warning"),
+    ("rpm", 1450, "1,450 rpm"),
 ])
 def test_a_value_reads_in_its_unit(unit, value, text):
     assert format_value(unit, value) == text
+
+
+_DISKS = Table("d", "disk", "9.2", "Disk", (Column("9.5", "status", "status", "state", states="words"),
+                                            Column("9.6", "temp", "temperature", "celsius")))
+
+
+def test_a_table_row_is_keyed_by_its_index_and_named_by_its_label():
+    got = table_readings(_DISKS, [{"index": "0", "label": "Disk 1", "columns": ["status", "temp"]},
+                                  {"index": "1", "label": "2", "columns": ["temp"]}])
+    assert [(r.oid, r.key, r.name, r.unit) for r in got] == [
+        ("9.5.0", "disk0_status", "Disk 1 status", "state"),
+        ("9.6.0", "disk0_temp", "Disk 1 temperature", "celsius"),
+        ("9.6.1", "disk1_temp", "Disk 2 temperature", "celsius")]       # a bare bay number gets its noun
+    assert got[0].states == "words"
+
+
+def test_a_table_without_labels_is_named_by_its_columns():
+    fans = Table("f", "", "", "Fan", (Column("9.2", "fan", "Fan speed", "rpm"),))
+    [one] = table_readings(fans, [{"index": "1", "label": "", "columns": ["fan"]}])
+    assert (one.key, one.name) == ("fan", "Fan speed")
+    two = table_readings(fans, [{"index": "1", "label": "", "columns": ["fan"]},
+                                {"index": "2", "label": "", "columns": ["fan"]}])
+    assert [(r.key, r.name) for r in two] == [("fan1", "Fan speed (fan 1)"), ("fan2", "Fan speed (fan 2)")]
+
+
+def test_rows_come_after_the_presets_only_for_ticked_presets_and_a_custom_name_wins():
+    rows = {"synology_volumes": [{"index": "0", "label": "Volume 1", "columns": ["status", "free"]}],
+            "asustor_fans": [{"index": "1", "label": "", "columns": ["fan"]}]}
+    keys = [r.key for r in device_readings(["system", "synology"], [], "1.3.6.1.9.9 raid0_free bytes", "2c", rows)]
+    assert keys[0] == "uptime" and "system_status" in keys and "fan" not in keys
+    assert keys.index("raid0_status") > keys.index("cpu_fan") and keys.count("raid0_free") == 1
+    assert keys[-1] == "raid0_free"                                      # the custom line, not the row
+    assert [t.id for t in tables_for(["asustor", "linux"])] == [
+        "ucd_diskio", "asustor_disks", "asustor_volumes", "asustor_temperatures", "asustor_memory", "asustor_fans"]
+
+
+def test_only_physical_disks_are_read_for_disk_load():
+    [diskio] = TABLES["linux"]
+    assert diskio.keeps("sda") and diskio.keeps("nvme0n1") and diskio.keeps("sata2")
+    assert not diskio.keeps("sda1") and not diskio.keeps("loop0") and not diskio.keeps("md2")
+
+
+@pytest.mark.parametrize("states, raw, want", [
+    ("synology_raid", 13, ("Data scrubbing", 1)),
+    ("synology_raid", 11.0, ("Degraded", 2)),
+    ("synology_raid", 1, ("Normal", 0)),
+    ("synology_disk", 5, ("Crashed", 3)),
+    ("synology_raid", 99, ("code 99", None)),
+    ("words", " Normal ", ("Normal", 0)),
+    ("words", "Healthy", ("Healthy", 0)),
+    ("words", "Unhealthy", ("Unhealthy", 3)),
+    ("words", "Degraded", ("Degraded", 2)),
+    ("words", "Resyncing", ("Resyncing", 1)),
+    ("words", "Broken", ("Broken", 3)),
+    ("words", "Frobnicated", ("Frobnicated", None)),
+])
+def test_a_vendor_state_reads_as_its_word_and_a_level(states, raw, want):
+    assert state_of(Reading("1.1", "s", "S", "state", states=states), raw) == want
+
+
+def test_a_state_shows_the_device_word_and_falls_back_to_its_level():
+    r = Reading("1.1", "raid0_status", "Volume 1 status", "state", states="synology_raid")
+    assert reading_text(r, 1.0, {"raid0_status": "Data scrubbing"}) == "Data scrubbing"
+    assert reading_text(r, 1.0, {}) == "Busy" and reading_text(r, None, None) == "—"