WIP autoscaler agent

agent/nix_builder_autoscaler/logging.py

@@ -0,0 +1,46 @@
+"""Structured JSON logging setup."""
+
+from __future__ import annotations
+
+import json
+import logging
+import sys
+from datetime import UTC, datetime
+from typing import Any
+
+
+class JSONFormatter(logging.Formatter):
+    """Format log records as single-line JSON."""
+
+    EXTRA_FIELDS = ("slot_id", "reservation_id", "instance_id", "request_id")
+
+    def format(self, record: logging.LogRecord) -> str:
+        """Format a log record as JSON."""
+        entry: dict[str, Any] = {
+            "ts": datetime.now(UTC).isoformat(),
+            "level": record.levelname,
+            "logger": record.name,
+            "message": record.getMessage(),
+        }
+        for field in self.EXTRA_FIELDS:
+            val = getattr(record, field, None)
+            if val is not None:
+                entry[field] = val
+        if record.exc_info and record.exc_info[1] is not None:
+            entry["exception"] = self.formatException(record.exc_info)
+        return json.dumps(entry, default=str)
+
+
+def setup_logging(level: str = "INFO") -> None:
+    """Configure the root logger with JSON output to stderr.
+
+    Args:
+        level: Log level name (DEBUG, INFO, WARNING, ERROR).
+    """
+    handler = logging.StreamHandler(sys.stderr)
+    handler.setFormatter(JSONFormatter())
+
+    root = logging.getLogger()
+    root.handlers.clear()
+    root.addHandler(handler)
+    root.setLevel(getattr(logging, level.upper(), logging.INFO))