add back fileExists method

Author: amymin00

src/index.ts

@@ -13,7 +13,8 @@ import {
   setLogger,
   setLogLevel,
 } from "./utils";
-import { extensionEnabled } from "./utils/extension-enabled";
+import { getExtensionPath } from "./utils/extension-path";
+import { existsSync } from "fs";
 
 export { TraceHeaders } from "./trace";
 
@@ -301,6 +302,8 @@ function isExtensionEnabled(): boolean {
   if (isExtension !== undefined) {
     return isExtension;
   }
-  isExtension = extensionEnabled();
+
+  const extensionPath = getExtensionPath();
+  isExtension = existsSync(extensionPath);
   return isExtension;
 }

src/metrics/extension.ts

@@ -1,14 +1,16 @@
 import { URL } from "url";
 import { get, post, logDebug, logError } from "../utils";
-import { extensionEnabled } from "../utils/extension-enabled";
+import { getExtensionPath } from "../utils/extension-path";
+import fs from "fs";
 
 export const AGENT_URL = "http://127.0.0.1:8124";
 const HELLO_PATH = "/lambda/hello";
 const FLUSH_PATH = "/lambda/flush";
 const AGENT_TIMEOUT_MS = 100;
 
 export async function isAgentRunning() {
-  const extensionExists = extensionEnabled();
+  const extensionPath = getExtensionPath();
+  const extensionExists = await fileExists(extensionPath);
   if (!extensionExists) {
     logDebug(`Agent isn't present in sandbox`);
     return false;
@@ -32,3 +34,10 @@ export async function flushExtension(): Promise<boolean> {
   }
   return true;
 }
+
+function fileExists(filename: string): Promise<boolean> {
+  return fs.promises
+    .access(filename, fs.constants.F_OK)
+    .then(() => true)
+    .catch(() => false);
+}

src/utils/extension-enabled.ts

@@ -0,0 +1,5 @@
+const EXTENSION_PATH = "/opt/extensions/datadog-agent";
+
+export function getExtensionPath() {
+  return EXTENSION_PATH;
+}