feat: add image route usage telemetry

apps/api/telemetry.py

@@ -0,0 +1,90 @@
+from __future__ import annotations
+
+import json
+import logging
+from time import perf_counter
+from typing import Any, Mapping
+
+
+logger = logging.getLogger("cmhub.api.generation_usage")
+
+EVENT_NAME = "generation_route_usage"
+MAX_CLIENT_VERSION_LENGTH = 64
+MAX_ALIAS_LENGTH = 64
+
+
+def telemetry_start_time() -> float:
+    return perf_counter()
+
+
+def telemetry_elapsed_ms(started: float) -> int:
+    return max(0, int((perf_counter() - started) * 1000))
+
+
+def request_alias(data: Mapping[str, Any]) -> str:
+    try:
+        return normalize_text(data.get("model", ""), MAX_ALIAS_LENGTH)
+    except AttributeError:
+        return ""
+
+
+def log_generation_route_usage(
+    *,
+    route_type: str,
+    request,
+    alias: str,
+    status: str,
+    latency_ms: int,
+    error_code: str = "",
+    http_status: int | None = None,
+) -> dict[str, Any]:
+    event = build_generation_route_usage_event(
+        route_type=route_type,
+        request=request,
+        alias=alias,
+        status=status,
+        latency_ms=latency_ms,
+        error_code=error_code,
+        http_status=http_status,
+    )
+    logger.info(
+        "%s %s",
+        EVENT_NAME,
+        json.dumps(event, ensure_ascii=False, sort_keys=True),
+        extra={"generation_route_usage": event},
+    )
+    return event
+
+
+def build_generation_route_usage_event(
+    *,
+    route_type: str,
+    request,
+    alias: str,
+    status: str,
+    latency_ms: int,
+    error_code: str = "",
+    http_status: int | None = None,
+) -> dict[str, Any]:
+    api_key = getattr(request, "auth", None)
+    user = getattr(request, "user", None)
+    return {
+        "event": EVENT_NAME,
+        "route_type": normalize_text(route_type, 16),
+        "api_key_id": getattr(api_key, "id", None),
+        "api_key_prefix": normalize_text(getattr(api_key, "key_prefix", ""), 32),
+        "user_id": getattr(user, "id", None),
+        "client_version": normalize_text(
+            request.headers.get("X-Client-Version", ""),
+            MAX_CLIENT_VERSION_LENGTH,
+        ),
+        "alias": normalize_text(alias, MAX_ALIAS_LENGTH),
+        "status": normalize_text(status, 32),
+        "latency_ms": max(0, int(latency_ms)),
+        "error_code": normalize_text(error_code, 64),
+        "http_status": http_status,
+    }
+
+
+def normalize_text(value: Any, max_length: int) -> str:
+    return str(value or "").strip()[:max_length]