feat: ensure we have a running Chrome process

src/lighthousePersist.ts

@@ -80,13 +80,49 @@ interface LighthousePersistResultInterface {
   opportunities?: OpportunitiesInterface[];
 }
 
+const GET_CHROME_PID_TIMEOUT_MILLISECONDS = 1000;
+const GET_CHROME_PID_TIMEOUT_SECONDS =
+  GET_CHROME_PID_TIMEOUT_MILLISECONDS / 1000;
+const MAX_GET_CHROME_PID_RETRIES = 10;
 const PROTOCOL_TIMEOUT = 'PROTOCOL_TIMEOUT';
 
 const createTimeout = (time: number) =>
   new Promise((resolve) => {
     setTimeout(resolve, time, PROTOCOL_TIMEOUT);
   });
 
+export const delay = (timeout: number) =>
+  new Promise((resolve) => setTimeout(resolve, timeout));
+
+// returns the Chrome process pid with retry logic
+const getChromePid = async ({
+  chrome,
+  retries = 0,
+  verbose,
+}: {
+  chrome: chromeLauncher.LaunchedChrome;
+  retries?: number;
+  verbose?: boolean;
+}): Promise<number | undefined> => {
+  if (typeof chrome.pid === 'number') {
+    return chrome.pid;
+  }
+  if (verbose) {
+    console.log('failed to get pid on retry', retries);
+  }
+  if (retries < MAX_GET_CHROME_PID_RETRIES) {
+    await delay(GET_CHROME_PID_TIMEOUT_MILLISECONDS);
+    if (verbose) {
+      console.log('trying again...');
+    }
+    return getChromePid({
+      chrome,
+      retries: retries + 1,
+    });
+  }
+  return;
+};
+
 // https://github.com/GoogleChrome/lighthouse/blob/master/docs/readme.md#using-programmatically
 export default async ({
   awsAccessKeyId: accessKeyId,
@@ -188,8 +224,17 @@ export default async ({
         });
       }
 
-      if (verbose) {
-        console.log('chrome pid', chrome.pid);
+      // ensure we actually have a running Chrome process
+      const chromePid = await getChromePid({
+        chrome,
+        verbose,
+      });
+
+      if (!chromePid) {
+        throw new Error(
+          `failed to find a running Chrome process with ${MAX_GET_CHROME_PID_RETRIES} ` +
+            `retries each with a ${GET_CHROME_PID_TIMEOUT_SECONDS} second delay`,
+        );
       }
 
       options.output = 'html';