feat: add system metrics dashboard

server/api/system.get.ts

@@ -0,0 +1,165 @@
+import fs from "node:fs"
+import os from "node:os"
+
+type CpuTimesSnapshot = {
+  idle: number
+  total: number
+}
+
+type NetworkSnapshot = {
+  rxBytes: number
+  txBytes: number
+  timestamp: number
+}
+
+let previousNetworkSnapshot: NetworkSnapshot | null = null
+
+function getCpuSnapshot(): CpuTimesSnapshot {
+  const cpus = os.cpus()
+
+  return cpus.reduce(
+    (snapshot, cpu) => {
+      const total = Object.values(cpu.times).reduce((sum, value) => sum + value, 0)
+
+      snapshot.idle += cpu.times.idle
+      snapshot.total += total
+
+      return snapshot
+    },
+    {idle: 0, total: 0}
+  )
+}
+
+function wait(durationMs: number) {
+  return new Promise((resolve) => {
+    setTimeout(resolve, durationMs)
+  })
+}
+
+async function getCpuUsagePercent(sampleMs: number) {
+  const start = getCpuSnapshot()
+  await wait(sampleMs)
+  const end = getCpuSnapshot()
+
+  const idleDelta = end.idle - start.idle
+  const totalDelta = end.total - start.total
+
+  if (totalDelta <= 0) {
+    return 0
+  }
+
+  return Math.max(0, Math.min(100, Math.round((1 - idleDelta / totalDelta) * 100)))
+}
+
+function getNetworkTotals() {
+  try {
+    const content = fs.readFileSync("/proc/net/dev", "utf8")
+    const totals = content
+      .split("\n")
+      .slice(2)
+      .map((line) => line.trim())
+      .filter(Boolean)
+      .reduce(
+        (accumulator, line) => {
+          const [namePart, valuesPart] = line.split(":")
+          const interfaceName = namePart?.trim()
+
+          if (!interfaceName || interfaceName === "lo" || !valuesPart) {
+            return accumulator
+          }
+
+          const values = valuesPart.trim().split(/\s+/)
+          const rxBytes = Number.parseInt(values[0] || "0", 10)
+          const txBytes = Number.parseInt(values[8] || "0", 10)
+
+          if (Number.isFinite(rxBytes)) {
+            accumulator.rxBytes += rxBytes
+          }
+
+          if (Number.isFinite(txBytes)) {
+            accumulator.txBytes += txBytes
+          }
+
+          return accumulator
+        },
+        {rxBytes: 0, txBytes: 0}
+      )
+
+    return totals
+  } catch {
+    return null
+  }
+}
+
+function getNetworkRatesMbps() {
+  const totals = getNetworkTotals()
+  const now = Date.now()
+
+  if (!totals) {
+    previousNetworkSnapshot = null
+    return {
+      incomingMbps: 0,
+      outgoingMbps: 0
+    }
+  }
+
+  const currentSnapshot: NetworkSnapshot = {
+    ...totals,
+    timestamp: now
+  }
+
+  if (!previousNetworkSnapshot) {
+    previousNetworkSnapshot = currentSnapshot
+
+    return {
+      incomingMbps: 0,
+      outgoingMbps: 0
+    }
+  }
+
+  const elapsedSeconds = (currentSnapshot.timestamp - previousNetworkSnapshot.timestamp) / 1000
+
+  if (elapsedSeconds <= 0) {
+    previousNetworkSnapshot = currentSnapshot
+
+    return {
+      incomingMbps: 0,
+      outgoingMbps: 0
+    }
+  }
+
+  const incomingMbps = Math.max(
+    0,
+    Number((((currentSnapshot.rxBytes - previousNetworkSnapshot.rxBytes) * 8) / elapsedSeconds / 1000000).toFixed(2))
+  )
+  const outgoingMbps = Math.max(
+    0,
+    Number((((currentSnapshot.txBytes - previousNetworkSnapshot.txBytes) * 8) / elapsedSeconds / 1000000).toFixed(2))
+  )
+
+  previousNetworkSnapshot = currentSnapshot
+
+  return {
+    incomingMbps,
+    outgoingMbps
+  }
+}
+
+export default defineEventHandler(async () => {
+  const totalMemory = os.totalmem()
+  const freeMemory = os.freemem()
+  const usedMemory = totalMemory - freeMemory
+  const memoryPercent = totalMemory > 0 ? Math.round((usedMemory / totalMemory) * 100) : 0
+  const cpuPercent = await getCpuUsagePercent(200)
+  const {incomingMbps, outgoingMbps} = getNetworkRatesMbps()
+
+  return {
+    cpuPercent,
+    memoryPercent,
+    totalMemory,
+    usedMemory,
+    incomingMbps,
+    outgoingMbps,
+    sampledAt: new Date().toISOString()
+  }
+})