feat: ship host metrics as a first-party in-process plugin

plugins/host-metrics/backend/managers/simple-reads.ts

@@ -0,0 +1,138 @@
+import type { Express } from "express";
+import { execCommand } from "../../../../src/backend/hosts/metrics-shared/common-utils.js";
+import { managerHandler } from "./route-helpers.js";
+import type { ManagerRoutesDeps } from "./types.js";
+
+// ─── Top by memory ──────────────────────────────────────────────────────────
+
+export interface MemProcessRow {
+  pid: number;
+  user: string;
+  mem: number;
+  rss: number;
+  command: string;
+}
+
+const TOP_MEM_CMD =
+  "ps -eo pid,user:20,pmem,rss,comm --sort=-pmem --no-headers 2>/dev/null | head -n 20";
+
+export function parseTopMemory(output: string): MemProcessRow[] {
+  const rows: MemProcessRow[] = [];
+  for (const raw of output.split("\n")) {
+    const line = raw.trim();
+    if (!line) continue;
+    const m = line.match(/^(\d+)\s+(\S+)\s+([\d.]+)\s+(\d+)\s+(.*)$/);
+    if (!m) continue;
+    rows.push({
+      pid: Number(m[1]),
+      user: m[2],
+      mem: Number(m[3]),
+      rss: Number(m[4]),
+      command: m[5],
+    });
+  }
+  return rows;
+}
+
+// ─── Systemd timers ─────────────────────────────────────────────────────────
+
+export interface TimerRow {
+  next: string;
+  left: string;
+  last: string;
+  unit: string;
+  activates: string;
+}
+
+const TIMERS_CMD =
+  "systemctl list-timers --all --no-legend --no-pager 2>/dev/null";
+
+export function parseTimers(output: string): TimerRow[] {
+  const rows: TimerRow[] = [];
+  for (const raw of output.split("\n")) {
+    const line = raw.trim();
+    if (!line || line.startsWith("NEXT")) continue;
+    // NEXT(3) LEFT(2) LAST(3) PASSED(2) UNIT ACTIVATES  -> columns vary; grab
+    // the trailing UNIT + ACTIVATES which always end the line.
+    const parts = line.split(/\s+/);
+    if (parts.length < 2) continue;
+    const activates = parts[parts.length - 1];
+    const unit = parts[parts.length - 2];
+    if (!unit.endsWith(".timer")) continue;
+    rows.push({
+      next: parts.slice(0, 3).join(" "),
+      left: "",
+      last: "",
+      unit,
+      activates,
+    });
+  }
+  return rows;
+}
+
+// ─── Disk breakdown (per-mount) ─────────────────────────────────────────────
+
+export interface MountUsage {
+  filesystem: string;
+  sizeKb: number;
+  usedKb: number;
+  availKb: number;
+  usePct: number;
+  mount: string;
+}
+
+const DF_CMD = "df -Pk 2>/dev/null | tail -n +2";
+
+export function parseDfMounts(output: string): MountUsage[] {
+  const mounts: MountUsage[] = [];
+  for (const raw of output.split("\n")) {
+    const line = raw.trim();
+    if (!line) continue;
+    const m = line.match(/^(\S+)\s+(\d+)\s+(\d+)\s+(\d+)\s+(\d+)%\s+(.+)$/);
+    if (!m) continue;
+    const fs = m[1];
+    // Skip pseudo/virtual filesystems that clutter the view.
+    if (/^(tmpfs|devtmpfs|overlay|udev|none|shm)$/.test(fs)) continue;
+    mounts.push({
+      filesystem: fs,
+      sizeKb: Number(m[2]),
+      usedKb: Number(m[3]),
+      availKb: Number(m[4]),
+      usePct: Number(m[5]),
+      mount: m[6],
+    });
+  }
+  return mounts;
+}
+
+export function registerSimpleReadRoutes(
+  app: Express,
+  { validateHostId, runOnHost }: ManagerRoutesDeps,
+): void {
+  app.get(
+    "/host-metrics/managers/top-memory/:id",
+    validateHostId,
+    managerHandler(runOnHost, "connect", "top_memory", async (client) => {
+      const { stdout } = await execCommand(client, TOP_MEM_CMD, 15000);
+      return { processes: parseTopMemory(stdout) };
+    }),
+  );
+
+  app.get(
+    "/host-metrics/managers/timers/:id",
+    validateHostId,
+    managerHandler(runOnHost, "connect", "systemd_timers", async (client) => {
+      const { stdout } = await execCommand(client, TIMERS_CMD, 15000);
+      return { timers: parseTimers(stdout) };
+    }),
+  );
+
+  app.get(
+    "/host-metrics/managers/disk-breakdown/:id",
+    validateHostId,
+    managerHandler(runOnHost, "connect", "disk_breakdown", async (client) => {
+      const { stdout } = await execCommand(client, DF_CMD, 15000);
+      return { mounts: parseDfMounts(stdout) };
+    }),
+  );
+}