feat(system-service): add PM2 picker and platform selection (#7114)

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Frank Elsinga <frank@elsinga.de>

test/backend-test/test-pm2.js

@@ -0,0 +1,123 @@
+const { describe, test, beforeEach, afterEach } = require("node:test");
+const assert = require("node:assert");
+const childProcess = require("child_process");
+const { DOWN, UP } = require("../../src/util");
+
+/**
+ * Load the PM2 monitor after swapping child_process.execFile.
+ * @param {typeof childProcess.execFile} execFileStub Stub implementation.
+ * @returns {import("../../server/monitor-types/pm2").PM2MonitorType} A PM2 monitor instance wired to the stub.
+ */
+function createMonitorType(execFileStub) {
+    childProcess.execFile = execFileStub;
+    delete require.cache[require.resolve("../../server/util/pm2")];
+    delete require.cache[require.resolve("../../server/monitor-types/pm2")];
+    const { PM2MonitorType } = require("../../server/monitor-types/pm2");
+    return new PM2MonitorType();
+}
+
+describe("PM2MonitorType", () => {
+    let monitorType;
+    let heartbeat;
+    let originalExecFile;
+
+    beforeEach(() => {
+        monitorType = null;
+        heartbeat = {
+            status: DOWN,
+            msg: "",
+        };
+        originalExecFile = childProcess.execFile;
+    });
+
+    afterEach(() => {
+        childProcess.execFile = originalExecFile;
+    });
+
+    test("check() returns UP for an online PM2 process", async () => {
+        monitorType = createMonitorType((command, args, options, callback) => {
+            callback(
+                null,
+                JSON.stringify([
+                    {
+                        pm_id: 0,
+                        name: "api",
+                        pm2_env: {
+                            status: "online",
+                        },
+                    },
+                ]),
+                ""
+            );
+        });
+
+        await monitorType.check(
+            {
+                system_service_name: "api",
+            },
+            heartbeat
+        );
+
+        assert.strictEqual(heartbeat.status, UP);
+        assert.ok(heartbeat.msg.includes("online"));
+    });
+
+    test("check() matches PM2 process by name when pm_id changes", async () => {
+        monitorType = createMonitorType((command, args, options, callback) => {
+            callback(
+                null,
+                JSON.stringify([
+                    {
+                        // PM2 may assign a different id when a process is deleted and recreated.
+                        pm_id: 7,
+                        name: "api",
+                        pm2_env: {
+                            status: "online",
+                        },
+                    },
+                ]),
+                ""
+            );
+        });
+
+        await monitorType.check(
+            {
+                system_service_name: "api",
+            },
+            heartbeat
+        );
+
+        assert.strictEqual(heartbeat.status, UP);
+        assert.ok(heartbeat.msg.includes("online"));
+    });
+
+    test("check() returns DOWN for a stopped PM2 process", async () => {
+        monitorType = createMonitorType((command, args, options, callback) => {
+            callback(
+                null,
+                JSON.stringify([
+                    {
+                        pm_id: 0,
+                        name: "api",
+                        pm2_env: {
+                            status: "stopped",
+                        },
+                    },
+                ]),
+                ""
+            );
+        });
+
+        await assert.rejects(
+            monitorType.check(
+                {
+                    system_service_name: "api",
+                },
+                heartbeat
+            ),
+            /stopped/
+        );
+
+        assert.strictEqual(heartbeat.status, DOWN);
+    });
+});