Add cluster overview landing page

Add an Overview page at / (top of the sidebar, filling the previously
blank root route) summarising the cluster: hosts connected, instances
running, users online, aggregate CPU/memory/disk usage, controller
uptime, a recent-errors panel (LogConsole), and a link to Grafana when
configured. Each card is gated by the relevant permission.

Adds a controller.grafana_url config field, read on the page via
ControllerConfigGetRequest, for the Grafana link.

Closes #928.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/lib/src/config/definitions.ts

@@ -18,6 +18,7 @@ export interface ControllerConfigFields {
 	"controller.bind_address": string | null;
 	"controller.trusted_proxies": string | null;
 	"controller.public_url": string | null;
+	"controller.grafana_url": string | null;
 	"controller.tls_certificate": string | null;
 	"controller.tls_private_key": string | null;
 	"controller.auth_secret": string | null;
@@ -137,6 +138,12 @@ export class ControllerConfig extends classes.Config<ControllerConfigFields> {
 			optional: true,
 			// TODO extendedValidation, valid url including the protocol
 		},
+		"controller.grafana_url": {
+			title: "Grafana URL",
+			description: "URL of a Grafana dashboard to link from the overview page, including the protocol.",
+			type: "string",
+			optional: true,
+		},
 		"controller.tls_certificate": {
 			title: "TLS Certificate",
 			description: "Path to the certificate to use for HTTPS.",

packages/web_ui/src/components/OverviewPage.tsx

@@ -0,0 +1,133 @@
+import React, { useContext, useEffect, useState } from "react";
+import { Row, Col, Card, Statistic, Progress, Button, Typography } from "antd";
+import { LineChartOutlined } from "@ant-design/icons";
+
+import * as lib from "@clusterio/lib";
+
+import { useAccount } from "../model/account";
+import { useHosts } from "../model/host";
+import { useInstances } from "../model/instance";
+import { useUsers, isUserOnline } from "../model/user";
+import { useSystems } from "../model/system";
+import ControlContext from "./ControlContext";
+import PageHeader from "./PageHeader";
+import PageLayout from "./PageLayout";
+import PluginExtra from "./PluginExtra";
+import LogConsole from "./LogConsole";
+import { MetricRelativeDate } from "./system_metrics";
+
+const { Title } = Typography;
+
+const sum = (values: number[]) => values.reduce((a, b) => a + b, 0);
+
+/** A resource card showing used / total with a usage bar. */
+function ResourceCard(
+	props: { title: string, used: number, total: number, format: (n: number) => string, unit?: string }
+) {
+	const percent = props.total > 0 ? Math.round((props.used / props.total) * 100) : 0;
+	const suffix = `/ ${props.format(props.total)}${props.unit ? ` ${props.unit}` : ""}`;
+	return <Card>
+		<Statistic title={props.title} value={props.format(props.used)} suffix={suffix} />
+		<Progress percent={percent} size="small" />
+	</Card>;
+}
+
+/** Format a core count: a fraction for partial use, a whole number for the total. */
+const formatCores = (n: number) => n.toLocaleString(undefined, { maximumFractionDigits: 1 });
+
+export default function OverviewPage() {
+	const account = useAccount();
+	const control = useContext(ControlContext);
+	const [hosts] = useHosts();
+	const [instances] = useInstances();
+	const [users] = useUsers();
+	const [systems] = useSystems();
+	const [grafanaUrl, setGrafanaUrl] = useState<string | null>(null);
+
+	const canHosts = account.hasPermission("core.host.list");
+	const canInstances = account.hasPermission("core.instance.list");
+	const canUsers = account.hasPermission("core.user.list");
+	const canLogs = account.hasPermission("core.log.follow");
+	const canConfig = account.hasPermission("core.controller.get_config");
+
+	useEffect(() => {
+		if (!canConfig) {
+			return undefined;
+		}
+		let canceled = false;
+		control.send(new lib.ControllerConfigGetRequest()).then(serialized => {
+			if (canceled) {
+				return;
+			}
+			const config = lib.ControllerConfig.fromJSON(serialized, "control");
+			const url = config.get("controller.grafana_url");
+			setGrafanaUrl(typeof url === "string" ? url : null);
+		}).catch(() => { /* link stays hidden if the config can't be read */ });
+		return () => { canceled = true; };
+	}, [control, canConfig]);
+
+	const hostList = [...hosts.values()];
+	const instanceList = [...instances.values()];
+	const userList = [...users.values()];
+	// Resource totals across the connected host machines (the controller is shown only for uptime).
+	const hostSystems = [...systems.values()].filter(system => system.id !== "controller");
+	const controllerSystem = systems.get("controller");
+
+	const colProps = { xs: 24, sm: 12, lg: 8 };
+
+	return <PageLayout nav={[{ name: "Overview" }]}>
+		<PageHeader
+			title="Overview"
+			extra={grafanaUrl
+				? <Button icon={<LineChartOutlined />} href={grafanaUrl} target="_blank" rel="noreferrer">
+					Grafana
+				</Button>
+				: undefined}
+		/>
+		<Row gutter={[16, 16]}>
+			{canHosts && <Col {...colProps}>
+				<Card>
+					<Statistic title="Hosts connected" value={hostList.filter(h => h.connected).length}
+						suffix={`/ ${hostList.length}`} />
+				</Card>
+			</Col>}
+			{canInstances && <Col {...colProps}>
+				<Card>
+					<Statistic title="Instances running" value={instanceList.filter(i => i.status === "running").length}
+						suffix={`/ ${instanceList.length}`} />
+				</Card>
+			</Col>}
+			{canUsers && <Col {...colProps}>
+				<Card>
+					<Statistic title="Users online" value={userList.filter(u => isUserOnline(u)).length}
+						suffix={`/ ${userList.length}`} />
+				</Card>
+			</Col>}
+			{canHosts && <>
+				<Col {...colProps}>
+					<ResourceCard title="CPU" used={sum(hostSystems.map(s => s.cpuUsed))}
+						total={sum(hostSystems.map(s => s.cpuCapacity))} format={formatCores} unit="cores" />
+				</Col>
+				<Col {...colProps}>
+					<ResourceCard title="Memory" used={sum(hostSystems.map(s => s.memoryUsed))}
+						total={sum(hostSystems.map(s => s.memoryCapacity))} format={lib.formatBytes} />
+				</Col>
+				<Col {...colProps}>
+					<ResourceCard title="Disk" used={sum(hostSystems.map(s => s.diskUsed))}
+						total={sum(hostSystems.map(s => s.diskCapacity))} format={lib.formatBytes} />
+				</Col>
+				<Col {...colProps}>
+					<Card>
+						<Statistic title="Controller running since"
+							formatter={() => <MetricRelativeDate timeMs={controllerSystem?.processStartedAtMs} />} />
+					</Card>
+				</Col>
+			</>}
+		</Row>
+		{canLogs && <>
+			<Title level={5} style={{ marginTop: 16 }}>Recent errors</Title>
+			<LogConsole all maxLevel="warn" />
+		</>}
+		<PluginExtra component="OverviewPage" />
+	</PageLayout>;
+}

packages/web_ui/src/pages.tsx

@@ -2,6 +2,7 @@ import React, { ReactElement } from "react";
 
 import { PluginPage, UserAccount } from "./BaseWebPlugin";
 
+import OverviewPage from "./components/OverviewPage";
 import ControllerPage from "./components/ControllerPage";
 import HostsPage from "./components/HostsPage";
 import HostViewPage from "./components/HostViewPage";
@@ -21,6 +22,11 @@ import IconReferencePage from "./components/IconReferencePage";
 // When adding or editing page paths here the corresponding webRoutes entry
 // in packages/controller/src/routes.ts also needs to be updated.
 export const pages: PluginPage[] = [
+	{
+		path: "/",
+		sidebarName: "Overview",
+		content: <OverviewPage />,
+	},
 	{
 		path: "/controller",
 		sidebarName: "Controller",