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lablink_client_service.monitoring.pusher

Push the session-metrics summary to the allocator.

The pusher swallows network exceptions — the integrity story is the allocator noticing we stop pushing, not any single POST. A 409 means the row was sealed (e.g. destroy already ran); the caller may choose to stop the agent.

A 200 response echoes the allocator's authoritative session-start timestamp (the DB's SessionStartedAt, null when the seat is free); the pusher writes it to the on-disk session anchor. That heals a lost anchor — e.g. the container was recreated mid-session and /tmp went with it — within one push interval: the monitoring loop re-anchors from the file on its next tick. Rewriting an unchanged value is a no-op for the loop, so this never causes reset oscillation.

POST one summary. Returns the HTTP status code or None on network error.

Source code in packages/client/src/lablink_client_service/monitoring/pusher.py 
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def push_summary(
    allocator_url: str,
    hostname: str,
    client_secret: str,
    counters: SessionCounters,
) -> int | None:
    """POST one summary. Returns the HTTP status code or None on network error."""
    body = _serialise_counters(counters)
    payload = {
        "session_started_at": body.pop("session_started_at"),
        "counters": body,
    }
    headers = {
        "Content-Type": "application/json",
        "Authorization": f"Bearer {client_secret}",
    }
    url = f"{allocator_url.rstrip('/')}/api/session-metrics/{hostname}"
    try:
        resp = requests.post(
            url=url,
            json=payload,
            headers=headers,
            timeout=POST_TIMEOUT_SECONDS,
        )
    except requests.exceptions.RequestException as e:
        logger.debug("session-metrics push failed: %s", e)
        return None
    if resp.status_code >= 400:
        logger.warning(
            "session-metrics POST returned %s: %s",
            resp.status_code,
            resp.text[:200],
        )
    elif resp.status_code == 200:
        _adopt_echoed_anchor(resp)
    return resp.status_code