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

plugins/host-metrics/backend/managers/services.ts

@@ -0,0 +1,135 @@
+import type { Express } from "express";
+import { execCommand } from "../../../../src/backend/hosts/metrics-shared/common-utils.js";
+import { execElevated } from "../../../../src/backend/hosts/metrics-shared/exec-elevated.js";
+import { managerHandler, ManagerInputError } from "./route-helpers.js";
+import {
+  isValidSystemdUnit,
+  isValidServiceAction,
+  type ServiceAction,
+} from "../../../../src/backend/hosts/metrics-shared/validation.js";
+import type { ManagerRoutesDeps } from "./types.js";
+
+export interface SystemdService {
+  unit: string;
+  load: string;
+  active: string;
+  sub: string;
+  description: string;
+}
+
+const LIST_SERVICES_CMD =
+  "systemctl list-units --type=service --all --no-legend --no-pager --plain 2>/dev/null";
+
+/** Parse `systemctl list-units --plain` output into structured rows. */
+export function parseServiceList(output: string): SystemdService[] {
+  const services: SystemdService[] = [];
+  for (const raw of output.split("\n")) {
+    const line = raw.trim();
+    if (!line) continue;
+    // Columns: UNIT LOAD ACTIVE SUB DESCRIPTION (description may contain spaces)
+    const parts = line.split(/\s+/);
+    if (parts.length < 4) continue;
+    const [unit, load, active, sub, ...rest] = parts;
+    if (!unit.endsWith(".service")) continue;
+    services.push({
+      unit,
+      load,
+      active,
+      sub,
+      description: rest.join(" "),
+    });
+  }
+  return services;
+}
+
+export function buildServiceActionCommand(
+  unit: string,
+  action: ServiceAction,
+): string {
+  return `systemctl ${action} ${unit}`;
+}
+
+export function registerServiceRoutes(
+  app: Express,
+  { validateHostId, runOnHost }: ManagerRoutesDeps,
+): void {
+  /**
+   * @openapi
+   * /host-metrics/managers/services/{id}:
+   *   get:
+   *     summary: List systemd services
+   *     tags: [Host Metrics]
+   *     parameters:
+   *       - in: path
+   *         name: id
+   *         required: true
+   *         schema: { type: integer }
+   *     responses:
+   *       200: { description: List of services. }
+   */
+  app.get(
+    "/host-metrics/managers/services/:id",
+    validateHostId,
+    managerHandler(runOnHost, "connect", "services_list", async (client) => {
+      const { stdout } = await execCommand(client, LIST_SERVICES_CMD, 20000);
+      return { services: parseServiceList(stdout) };
+    }),
+  );
+
+  /**
+   * @openapi
+   * /host-metrics/managers/services/{id}/action:
+   *   post:
+   *     summary: Start/stop/restart/enable/disable a systemd service
+   *     tags: [Host Metrics]
+   *     parameters:
+   *       - in: path
+   *         name: id
+   *         required: true
+   *         schema: { type: integer }
+   *     requestBody:
+   *       required: true
+   *       content:
+   *         application/json:
+   *           schema:
+   *             type: object
+   *             properties:
+   *               unit: { type: string }
+   *               action: { type: string }
+   *     responses:
+   *       200: { description: Action result. }
+   *       400: { description: Invalid unit or action. }
+   *       403: { description: Elevation required or denied. }
+   */
+  app.post(
+    "/host-metrics/managers/services/:id/action",
+    validateHostId,
+    managerHandler(
+      runOnHost,
+      "connect",
+      "services_action",
+      async (client, host, req) => {
+        const { unit, action } = req.body as {
+          unit?: string;
+          action?: string;
+        };
+        if (!isValidSystemdUnit(unit)) {
+          throw new ManagerInputError("Invalid unit name");
+        }
+        if (!isValidServiceAction(action)) {
+          throw new ManagerInputError("Invalid action");
+        }
+        const result = await execElevated(
+          client,
+          buildServiceActionCommand(unit, action),
+          host.sudoPassword,
+          { forceSudo: true, timeoutMs: 30000 },
+        );
+        return {
+          success: result.code === 0,
+          output: result.stdout || result.stderr,
+        };
+      },
+    ),
+  );
+}