feat: live docker/database widgets over WebSocket (M2)

Adds a custom server.ts (http server + Next request handler + a
noServer:true WebSocket server on /ws) so the app can push live data
without polling. A CollectorScheduler runs one interval-based job per
docker/database widget instance, backed by dockerode against
/var/run/docker.sock, and reconciles jobs when config.yml changes.

Config hot-reload is now fully wired: chokidar watches config.yml/.env,
re-validates on change, and broadcasts config:update (or a
non-destructive config:error, keeping the last-good config) to every
connected browser. The client subscribes to per-widget topics over a
single shared WebSocket with exponential-backoff reconnect and
last-result caching for instant resubscribe.

Verified end-to-end against real throwaway containers (nginx, redis):
live CPU/mem/uptime/health streamed over the socket, interval changes
picked up without a server restart, and a broken config.yml correctly
falls back to the last-valid config instead of crashing the app.
This commit is contained in:
2026-08-17 14:01:53 +02:00
parent 80c2362ac2
commit 9890f964c5
17 changed files with 693 additions and 7 deletions
+136
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"use client";
import { useEffect, useState } from "react";
import type { Config } from "@/lib/config/schema";
import type { WidgetResult } from "@/lib/types/widget-result";
interface Envelope {
topic: string;
type: string;
ts: number;
data: unknown;
}
type TopicListener = (envelope: Envelope) => void;
let sharedSocket: WebSocket | null = null;
let refCount = 0;
let reconnectAttempts = 0;
let reconnectTimer: ReturnType<typeof setTimeout> | null = null;
const topicListeners = new Map<string, Set<TopicListener>>();
const pendingWidgetSubscriptions = new Set<string>();
function getSocketUrl(): string {
const protocol = window.location.protocol === "https:" ? "wss:" : "ws:";
return `${protocol}//${window.location.host}/ws`;
}
function scheduleReconnect(): void {
if (reconnectTimer || refCount === 0) return;
const delay = Math.min(30_000, 1_000 * 2 ** reconnectAttempts);
reconnectAttempts += 1;
reconnectTimer = setTimeout(() => {
reconnectTimer = null;
if (refCount > 0) ensureSocket();
}, delay);
}
function ensureSocket(): WebSocket {
if (sharedSocket && sharedSocket.readyState <= WebSocket.OPEN) {
return sharedSocket;
}
const socket = new WebSocket(getSocketUrl());
sharedSocket = socket;
socket.addEventListener("open", () => {
reconnectAttempts = 0;
for (const widgetId of pendingWidgetSubscriptions) {
socket.send(JSON.stringify({ action: "subscribe", widgetId }));
}
});
socket.addEventListener("message", (event) => {
let envelope: Envelope;
try {
envelope = JSON.parse(event.data);
} catch {
return;
}
const listeners = topicListeners.get(envelope.topic);
if (!listeners) return;
for (const listener of listeners) listener(envelope);
});
socket.addEventListener("close", () => {
if (sharedSocket === socket) sharedSocket = null;
scheduleReconnect();
});
return socket;
}
function addTopicListener(topic: string, listener: TopicListener): () => void {
let listeners = topicListeners.get(topic);
if (!listeners) {
listeners = new Set();
topicListeners.set(topic, listeners);
}
listeners.add(listener);
return () => {
listeners?.delete(listener);
if (listeners && listeners.size === 0) topicListeners.delete(topic);
};
}
export function useWidgetSubscription(widgetId: string): WidgetResult | null {
const [result, setResult] = useState<WidgetResult | null>(null);
useEffect(() => {
refCount += 1;
pendingWidgetSubscriptions.add(widgetId);
const socket = ensureSocket();
const topic = `widget:${widgetId}`;
const removeListener = addTopicListener(topic, (envelope) => {
if (envelope.type === "result") setResult(envelope.data as WidgetResult);
});
if (socket.readyState === WebSocket.OPEN) {
socket.send(JSON.stringify({ action: "subscribe", widgetId }));
}
return () => {
refCount -= 1;
removeListener();
if (!topicListeners.has(topic)) {
pendingWidgetSubscriptions.delete(widgetId);
if (socket.readyState === WebSocket.OPEN) {
socket.send(JSON.stringify({ action: "unsubscribe", widgetId }));
}
}
};
}, [widgetId]);
return result;
}
export function useConfigSubscription(initial: Config): Config {
const [config, setConfig] = useState(initial);
useEffect(() => {
refCount += 1;
ensureSocket();
const removeListener = addTopicListener("config", (envelope) => {
if (envelope.type === "config:update") setConfig(envelope.data as Config);
});
return () => {
refCount -= 1;
removeListener();
};
}, []);
return config;
}
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import type { Server as HttpServer } from "node:http";
import { WebSocket, WebSocketServer } from "ws";
import { collectorScheduler } from "@/lib/collectors/scheduler";
import { configStore, type ConfigError } from "@/lib/config/loader";
import type { Config } from "@/lib/config/schema";
import type { WidgetResult } from "@/lib/types/widget-result";
type Envelope =
| { topic: string; type: "result"; ts: number; data: WidgetResult }
| { topic: "config"; type: "config:update"; ts: number; data: Config }
| { topic: "config"; type: "config:error"; ts: number; data: { message: string } };
function send(socket: WebSocket, envelope: Envelope): void {
if (socket.readyState === WebSocket.OPEN) {
socket.send(JSON.stringify(envelope));
}
}
export function attachWebSocketServer(httpServer: HttpServer): WebSocketServer {
const wss = new WebSocketServer({ noServer: true });
const subscriptions = new Map<string, Set<WebSocket>>();
const allSockets = new Set<WebSocket>();
function subscribe(socket: WebSocket, widgetId: string): void {
let set = subscriptions.get(widgetId);
if (!set) {
set = new Set();
subscriptions.set(widgetId, set);
}
set.add(socket);
const cached = collectorScheduler.getLastResult(widgetId);
if (cached) {
send(socket, { topic: `widget:${widgetId}`, type: "result", ts: Date.now(), data: cached });
}
}
function unsubscribe(socket: WebSocket, widgetId: string): void {
subscriptions.get(widgetId)?.delete(socket);
}
function cleanupSocket(socket: WebSocket): void {
allSockets.delete(socket);
for (const set of subscriptions.values()) set.delete(socket);
}
wss.on("connection", (socket) => {
allSockets.add(socket);
try {
const config = configStore.get();
send(socket, { topic: "config", type: "config:update", ts: Date.now(), data: config });
} catch {
// no valid config loaded yet; client keeps its SSR-seeded config until one arrives
}
socket.on("message", (raw) => {
let message: { action?: string; widgetId?: string };
try {
message = JSON.parse(raw.toString());
} catch {
return;
}
if (message.action === "subscribe" && typeof message.widgetId === "string") {
subscribe(socket, message.widgetId);
} else if (message.action === "unsubscribe" && typeof message.widgetId === "string") {
unsubscribe(socket, message.widgetId);
}
});
socket.on("close", () => cleanupSocket(socket));
socket.on("error", () => cleanupSocket(socket));
});
collectorScheduler.onResult((widgetId, result) => {
const set = subscriptions.get(widgetId);
if (!set || set.size === 0) return;
const envelope: Envelope = { topic: `widget:${widgetId}`, type: "result", ts: Date.now(), data: result };
for (const socket of set) send(socket, envelope);
});
configStore.onUpdate((config) => {
const envelope: Envelope = { topic: "config", type: "config:update", ts: Date.now(), data: config };
for (const socket of allSockets) send(socket, envelope);
});
configStore.onError((error: ConfigError) => {
const envelope: Envelope = {
topic: "config",
type: "config:error",
ts: Date.now(),
data: { message: error.message },
};
for (const socket of allSockets) send(socket, envelope);
});
httpServer.on("close", () => wss.close());
return wss;
}