86 lines
4.8 KiB
PHP
86 lines
4.8 KiB
PHP
<?php
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// ═══════════════════════════════════════════════════════════════════════════════════════════════
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// PURPOSE
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// Watchdog data endpoint. Every watchdog's current state for every node in one document —
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// resource, docker, system, storage, network and stability — together with the thresholds
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// each one is judging against, for the watchdog tab's poll.
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//
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// OPERATIONAL MODEL
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// Served from a 5-minute cache unless ?live is present. Assembling this payload reads every
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// watchdog's state files and resolves every threshold out of master.conf, which is far more
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// work than the tab's poll needs — the watchdogs themselves only run every 15 minutes, so a
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// fresher answer would describe the same cycle.
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//
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// The cache is consulted before include/watchdog.php is even loaded, so a cache hit costs one
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// file read and nothing else. ?live skips the read, recomputes, and writes the result back, so
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// an explicit refresh also benefits the next visitor rather than being discarded.
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//
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// DESIGN PRINCIPLES
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// Thin transport. State-file parsing and threshold resolution live in
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// include/watchdog.php; this file only sets the content type and encodes.
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//
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// Thresholds ship with the state, not separately.
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// vv_wd_all() resolves every threshold from master.conf into the same payload as the
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// counters they apply to. A strike count means nothing without the limit it is counted
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// against, so the page never has to fetch the two independently and risk mismatching
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// them across a conf edit.
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//
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// The only parameter is a freshness override. ?live decides how old an answer may be, never
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// what is in it — which watchdogs exist is fixed by the codebase, and no request can select,
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// filter or widen the set.
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//
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// OPERATIONAL SAFEGUARDS
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// Read-only. Nothing here clears a strike, lifts a skip-list entry, restarts a container,
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// or cancels a pending reboot. The watchdogs own their own state; this endpoint reports it.
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//
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// Absent counters are reported quiet, not alarming.
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// A watchdog that has not yet written state reads as zero rather than unknown, so a
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// fresh boot does not light the page up with false strikes.
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//
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// Thresholds fall back to the shipped defaults.
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// Every vv_wd_scalar() lookup has a ?: default, so a master.conf that is mid-edit or
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// missing a key still yields a coherent payload instead of comparing counters against
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// zero and declaring everything critical.
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//
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// Remote collection degrades per node — one unreachable partner drops that node's card and
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// leaves the local host and every other partner intact.
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//
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// Served from cache, collected only on a miss.
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// vv_wd_all() SSHes to every configured partner, so its cost is set by the slowest node
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// rather than by how much data there is. Measured at 8.3s on this host with the partner unreachable —
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// paid by every visitor, every 30 seconds, because the tab polls. The cache check happens
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// before the heavy include, so a hit costs one file read and no SSH at all.
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//
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// The window is deliberately wider than the poll. Watchdog state only changes when the
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// orchestrator runs, which is every 15 minutes; polling it every 30 seconds was never
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// reading anything new, it was just re-paying for the same answer.
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//
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// REQUEST
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// GET served from the 300s cache when one is present
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// GET ?live bypass the cache and collect everything fresh
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//
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// RESPONSE
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// vv_wd_all() verbatim — per-node watchdog state plus the resolved threshold set
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//
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// DEPENDS ON
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// include/config.php vv_cache_read()
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// include/watchdog.php vv_wd_all() — required only on a miss
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// Tools/api_cache_writer.php writes the cache this endpoint normally serves
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// ═══════════════════════════════════════════════════════════════════════════════════════════════
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header('Content-Type: application/json');
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require_once dirname(__DIR__) . '/include/config.php';
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if (!isset($_GET['live'])) {
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$_vv_cached = vv_cache_read('watchdog', 300);
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if ($_vv_cached !== null) { echo json_encode($_vv_cached); exit; }
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unset($_vv_cached);
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}
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require_once dirname(__DIR__) . '/include/watchdog.php';
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$_vv_wd = vv_wd_all();
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// Written on the miss as well as by the background writer. Without this the first visitor after
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// a restart pays the full collection and so does the next one, until the writer's next minute
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// happens to land.
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vv_cache_write('watchdog', $_vv_wd);
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echo json_encode($_vv_wd);
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