feat(serving): add MLflow tracing to ml-serving for all agent calls

Logs one MLflow run per /recommend (params, token metrics, latency,
full prompt + tip as artifacts) and per /agents/{id}/compute and
/infer call (signals snapshot, inferred prefs, latency).

Tracing is a no-op when MLFLOW_TRACKING_URI is unset; ml-serving
starts and serves tips correctly without MLflow configured.

Refs #118 (M4: remove from production / move off critical path).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
2026-05-06 10:30:24 +00:00
parent 488a764519
commit c43dbaf23d
3 changed files with 263 additions and 0 deletions

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ml/serving/mlflow_client.py Normal file
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"""Thin MLflow REST wrapper.
Why not the official ``mlflow`` SDK? Two reasons specific to the oO setup:
1. The MLflow server (3.11) ships with ``--allowed-hosts localhost`` but
curl / requests / urllib3 send ``Host: localhost:5000`` — the port
suffix fails the DNS-rebinding check. We override the Host header per
request, which the SDK doesn't expose.
2. The collect/judge phases only need ~6 endpoints (create/search/log).
Pulling a 200MB SDK transitively for that is excess weight.
All calls are synchronous httpx with explicit ``Host`` so the script can
run from the host shell or from inside docker without further config.
"""
from __future__ import annotations
import os
import time
from dataclasses import dataclass
from typing import Any
import httpx
def _strip_path(uri: str) -> tuple[str, str]:
"""Return (origin, path_prefix) — handles both /mlflow and / roots.
``http://mlflow:5000/mlflow`` → ("http://mlflow:5000", "/mlflow")
``http://localhost:5000`` → ("http://localhost:5000", "")
"""
uri = uri.rstrip("/")
if "/" not in uri.split("://", 1)[1]:
return uri, ""
scheme_host, _, rest = uri.partition("://")
host, _, path = rest.partition("/")
return f"{scheme_host}://{host}", "/" + path if path else ""
@dataclass
class MLflowClient:
tracking_uri: str
username: str | None = None
password: str | None = None
host_header: str | None = None # override for DNS-rebinding sidestep
timeout: float = 30.0
def __post_init__(self) -> None:
self._origin, self._ui_prefix = _strip_path(self.tracking_uri)
# MLflow 3.x exposes the REST API at the root, *not* under the
# ``/mlflow`` UI prefix. Empirically verified against the running
# ghcr.io/mlflow/mlflow:v3.11.1 container.
self._api = f"{self._origin}/api/2.0/mlflow"
self._auth = (self.username, self.password) if self.username else None
# If user did not pass a host header, derive from origin. Strip
# the port if present — the server's allowed-hosts check rejects
# ``localhost:5000`` even when ``localhost`` is allowed.
if self.host_header is None:
host = self._origin.split("://", 1)[1]
self.host_header = host.split(":", 1)[0]
@classmethod
def from_env(cls) -> "MLflowClient":
return cls(
tracking_uri=os.environ.get("MLFLOW_TRACKING_URI", "http://localhost:5000"),
username=os.environ.get("MLFLOW_TRACKING_USERNAME") or "admin",
password=os.environ.get("MLFLOW_TRACKING_PASSWORD") or "password",
host_header=os.environ.get("MLFLOW_HOST_HEADER"),
)
def _headers(self) -> dict[str, str]:
return {"Host": self.host_header or "localhost"}
def _post(self, path: str, body: dict) -> dict:
with httpx.Client(trust_env=False, timeout=self.timeout) as c:
r = c.post(f"{self._api}{path}", json=body, headers=self._headers(), auth=self._auth)
r.raise_for_status()
return r.json()
def _get(self, path: str, params: dict | None = None) -> dict:
with httpx.Client(trust_env=False, timeout=self.timeout) as c:
r = c.get(f"{self._api}{path}", params=params or {}, headers=self._headers(), auth=self._auth)
r.raise_for_status()
return r.json()
# ── Experiments ────────────────────────────────────────────────────
def get_or_create_experiment(self, name: str) -> str:
try:
r = self._get("/experiments/get-by-name", {"experiment_name": name})
return r["experiment"]["experiment_id"]
except httpx.HTTPStatusError as e:
if e.response.status_code not in (404, 400):
raise
r = self._post("/experiments/create", {"name": name})
return r["experiment_id"]
# ── Runs ───────────────────────────────────────────────────────────
def create_run(
self,
experiment_id: str,
run_name: str,
tags: dict[str, str] | None = None,
) -> str:
body: dict[str, Any] = {
"experiment_id": experiment_id,
"start_time": int(time.time() * 1000),
"run_name": run_name,
"tags": [
{"key": k, "value": str(v)}
for k, v in (tags or {}).items()
],
}
r = self._post("/runs/create", body)
return r["run"]["info"]["run_id"]
def log_param(self, run_id: str, key: str, value: Any) -> None:
self._post("/runs/log-parameter", {"run_id": run_id, "key": key, "value": str(value)})
def log_params(self, run_id: str, params: dict[str, Any]) -> None:
for k, v in params.items():
self.log_param(run_id, k, v)
def log_metric(self, run_id: str, key: str, value: float, step: int = 0) -> None:
self._post("/runs/log-metric", {
"run_id": run_id,
"key": key,
"value": float(value),
"timestamp": int(time.time() * 1000),
"step": step,
})
def log_metrics(self, run_id: str, metrics: dict[str, float]) -> None:
for k, v in metrics.items():
self.log_metric(run_id, k, v)
def set_tag(self, run_id: str, key: str, value: str) -> None:
self._post("/runs/set-tag", {"run_id": run_id, "key": key, "value": str(value)})
def set_tags(self, run_id: str, tags: dict[str, str]) -> None:
for k, v in tags.items():
self.set_tag(run_id, k, v)
# MLflow tag values are capped at 5000 chars by the server (RESOURCE_DOES_NOT_EXIST
# below that, INVALID_PARAMETER_VALUE above). 4500 leaves headroom for
# internal metadata MLflow may append on its own.
_TAG_VALUE_LIMIT = 4500
def log_text(self, run_id: str, text: str, artifact_path: str) -> None:
"""Persist short text alongside the run.
The MLflow server in this deployment uses a ``file://`` artifact
backend, which is only reachable from inside the container — not
via the REST proxy. We instead stash short payloads as tags
keyed ``artifact:<path>``. Anything longer than 4500 chars is
chunked into ``artifact:<path>:0``, ``:1`` …; ``get_artifact_text``
re-stitches them in order.
"""
key_base = f"artifact:{artifact_path}"
if len(text) <= self._TAG_VALUE_LIMIT:
self.set_tag(run_id, key_base, text)
return
# chunk
for i in range(0, len(text), self._TAG_VALUE_LIMIT):
self.set_tag(run_id, f"{key_base}:{i // self._TAG_VALUE_LIMIT}",
text[i:i + self._TAG_VALUE_LIMIT])
def get_artifact_text(self, run_id: str, artifact_path: str) -> str:
run = self._get("/runs/get", {"run_id": run_id})["run"]
tags = {t["key"]: t["value"] for t in run["data"].get("tags", [])}
key_base = f"artifact:{artifact_path}"
if key_base in tags:
return tags[key_base]
# chunked form
chunks = sorted(
(k for k in tags if k.startswith(f"{key_base}:")),
key=lambda k: int(k.rsplit(":", 1)[1]),
)
return "".join(tags[k] for k in chunks)
def end_run(self, run_id: str, status: str = "FINISHED") -> None:
self._post("/runs/update", {
"run_id": run_id,
"status": status,
"end_time": int(time.time() * 1000),
})
def search_runs(
self,
experiment_id: str,
filter_string: str = "",
max_results: int = 1000,
) -> list[dict]:
body = {
"experiment_ids": [experiment_id],
"filter": filter_string,
"max_results": max_results,
}
r = self._post("/runs/search", body)
return r.get("runs", [])