Initial Template.

src/meta/monitor.py

@@ -0,0 +1,139 @@
+import logging
+import asyncio
+from enum import IntEnum
+from collections import deque, ChainMap
+import datetime as dt
+
+logger = logging.getLogger(__name__)
+
+
+class StatusLevel(IntEnum):
+    ERRORED = -2
+    UNSURE = -1
+    WAITING = 0
+    STARTING = 1
+    OKAY = 2
+
+    @property
+    def symbol(self):
+        return symbols[self]
+
+
+symbols = {
+    StatusLevel.ERRORED: '🟥',
+    StatusLevel.UNSURE: '🟧',
+    StatusLevel.WAITING: '⬜',
+    StatusLevel.STARTING: '🟫',
+    StatusLevel.OKAY: '🟩',
+}
+
+
+class ComponentStatus:
+    def __init__(self, level: StatusLevel, short_formatstr: str, long_formatstr: str, data: dict = {}):
+        self.level = level
+        self.short_formatstr = short_formatstr
+        self.long_formatstr = long_formatstr
+        self.data = data
+        self.created_at = dt.datetime.now(tz=dt.timezone.utc)
+
+    def format_args(self):
+        extra = {
+            'created_at': self.created_at,
+            'level': self.level,
+            'symbol': self.level.symbol,
+        }
+        return ChainMap(extra, self.data)
+
+    @property
+    def short(self):
+        return self.short_formatstr.format(**self.format_args())
+
+    @property
+    def long(self):
+        return self.long_formatstr.format(**self.format_args())
+
+
+class ComponentMonitor:
+    _name = None
+
+    def __init__(self, name=None, callback=None):
+        self._callback = callback
+        self.name = name or self._name
+        if not self.name:
+            raise ValueError("ComponentMonitor must have a name")
+
+    async def _make_status(self, *args, **kwargs):
+        if self._callback is not None:
+            return await self._callback(*args, **kwargs)
+        else:
+            raise NotImplementedError
+
+    async def status(self) -> ComponentStatus:
+        try:
+            status = await self._make_status()
+        except Exception as e:
+            logger.exception(
+                f"Status callback for component '{self.name}' failed. This should not happen."
+            )
+            status = ComponentStatus(
+                level=StatusLevel.UNSURE,
+                short_formatstr="Status callback for '{name}' failed with error '{error}'",
+                long_formatstr="Status callback for '{name}' failed with error '{error}'",
+                data={
+                    'name': self.name,
+                    'error': repr(e)
+                }
+            )
+        return status
+
+
+class SystemMonitor:
+    def __init__(self):
+        self.components = {}
+        self.recent = deque(maxlen=10)
+
+    def add_component(self, component: ComponentMonitor):
+        self.components[component.name] = component
+        return component
+
+    async def request(self):
+        """
+        Request status from each component.
+        """
+        tasks = {
+            name: asyncio.create_task(comp.status())
+            for name, comp in self.components.items()
+        }
+        await asyncio.gather(*tasks.values())
+        status = {
+            name: await fut for name, fut in tasks.items()
+        }
+        self.recent.append(status)
+        return status
+
+    async def _format_summary(self, status_dict: dict[str, ComponentStatus]):
+        """
+        Format a one line summary from a status dict.
+        """
+        freq = {level: 0 for level in StatusLevel}
+        for status in status_dict.values():
+            freq[status.level] += 1
+
+        summary = '\t'.join(f"{level.symbol} {count}" for level, count in freq.items() if count)
+        return summary
+
+    async def _format_overview(self, status_dict: dict[str, ComponentStatus]):
+        """
+        Format an overview (one line per component) from a status dict.
+        """
+        lines = []
+        for name, status in status_dict.items():
+            lines.append(f"{status.level.symbol} {name}: {status.short}")
+        summary = await self._format_summary(status_dict)
+        return '\n'.join((summary, *lines))
+
+    async def get_summary(self):
+        return await self._format_summary(await self.request())
+
+    async def get_overview(self):
+        return await self._format_overview(await self.request())