Running/shutdown utilities

Summary: Create utilities to check for existing running instances and shutdown.

Reviewed By: ivanmisuno

Differential Revision: D49593321

fbshipit-source-id: 10acdb4f340f2f24f9ebd3203153906b34623178

desktop/flipper-server-core/src/server/utilities.tsx

@@ -11,6 +11,9 @@ import os from 'os';
 import xdgBasedir from 'xdg-basedir';
 import net from 'net';
 import fs from 'fs-extra';
+import fetch from 'node-fetch';
+import {EnvironmentInfo} from 'flipper-common';
+import semver from 'semver';
 
 /**
  * Checks if a port is in use.
@@ -39,3 +42,66 @@ export async function checkPortInUse(port: number): Promise<boolean> {
       .listen(port);
   });
 }
+
+/**
+ * Checks if a running Flipper server is available on the given port.
+ * @param port The port to check.
+ * @returns If successful, it will return the version of the running
+ * Flipper server. Otherwise, undefined.
+ */
+export async function checkServerRunning(
+  port: number,
+): Promise<string | undefined> {
+  try {
+    const response = await fetch(`http://localhost:${port}/info`);
+    if (response.status >= 200 && response.status < 300) {
+      const environmentInfo: EnvironmentInfo = await response.json();
+      return environmentInfo.appVersion;
+    } else {
+      console.info(
+        '[flipper-server] Running instance found, failed with HTTP status code: ',
+        response.status,
+      );
+    }
+  } catch (e) {
+    console.info(
+      `[flipper-server] No running instance found, error found: ${e}`,
+    );
+  }
+}
+
+/**
+ * Attempts to shutdown an existing Flipper server instance.
+ * @param port The port of the running Flipper server
+ * @returns Returns true if the shutdown was successful. Otherwise, false.
+ */
+export async function shutdownRunningInstance(port: number): Promise<boolean> {
+  try {
+    const response = await fetch(`http://localhost:${port}/shutdown`);
+    if (response.status >= 200 && response.status < 300) {
+      const json = await response.json();
+      console.info(
+        `[flipper-server] Shutdown request acknowledge: ${json?.success}`,
+      );
+      return json?.success;
+    } else {
+      console.warn(
+        '[flipper-server] Shutdown request not handled, HTTP status code: ',
+        response.status,
+      );
+    }
+  } catch (e) {
+    console.warn('[flipper-server] Shutdown request failed with error: ', e);
+  }
+
+  return false;
+}
+
+/**
+ * Compares two versions excluding build identifiers
+ * (the bit after + in the semantic version string).
+ * @return 0 if v1 == v2, 1 if v1 is greater, -1 if v2 is greater.
+ */
+export function compareServerVersion(v1: string, v2: string): number {
+  return semver.compare(v1, v2);
+}