Handle GitHub API rate limits in script

docs/scripts/update-contributors.js

@@ -1,4 +1,5 @@
 import fs from "node:fs/promises";
+import timers from "node:timers/promises";
 import { URL } from "node:url";
 
 const MAINTAINERS = {
@@ -220,16 +221,61 @@ class UserFetchError extends Error {
   }
 }
 
-async function fetchUserInfo(username) {
-  const res = await fetch(`https://api.github.com/users/${username}`, {
+const BACKOFF_INTERVALS_MINUTES = [1, 2, 3, 5];
+const MAX_RETRIES = BACKOFF_INTERVALS_MINUTES.length - 1;
+
+async function rateLimitDelay({ retryAfter, ratelimitReset, retryCount }) {
+  let timeoutInMilliseconds = BACKOFF_INTERVALS_MINUTES[retryCount] * 1000;
+  if (retryAfter) {
+    timeoutInMilliseconds = retryAfter * 1000;
+  } else if (ratelimitRemaining === "0" && ratelimitReset) {
+    timeoutInMilliseconds = ratelimitReset * 1000 - Date.now();
+  }
+
+  const timeoutInSeconds = (timeoutInMilliseconds / 1000).toLocaleString();
+  console.warn(`Waiting for ${timeoutInSeconds} seconds...`);
+
+  await timers.setTimeout(timeoutInMilliseconds);
+}
+
+async function fetchUserInfo(username, retryCount = 0) {
+  if (retryCount >= MAX_RETRIES) {
+    throw new Error(`Hit max retries (${MAX_RETRIES}) for fetching user ${username}`);
+  }
+
+  const request = new Request(`https://api.github.com/users/${username}`, {
     headers: {
       Accept: "application/vnd.github+json",
       "X-GitHub-Api-Version": "2022-11-28",
     },
   });
+  if (process.env.GITHUB_TOKEN) {
+    request.headers.set("Authorization", `Bearer ${process.env.GITHUB_TOKEN}`);
+  }
+
+  const res = await fetch(request);
+
   if (!res.ok) {
+    const retryAfter = res.headers.get("retry-after"); // seconds
+    const ratelimitRemaining = res.headers.get("x-ratelimit-remaining"); // quantity of requests remaining
+    const ratelimitReset = res.headers.get("x-ratelimit-reset"); // UTC epoch seconds
+
+    if (retryAfter || ratelimitRemaining === "0" || ratelimitReset) {
+      // See https://docs.github.com/en/rest/using-the-rest-api/best-practices-for-using-the-rest-api?apiVersion=2022-11-28#handle-rate-limit-errors-appropriately
+      console.warn("Rate limited by GitHub API");
+
+      await rateLimitDelay({
+        retryAfter,
+        ratelimitReset,
+        retryCount,
+      });
+
+      return await fetchUserInfo(username, retryCount + 1);
+    }
+
     throw new UserFetchError(`${res.url} responded with ${res.status}`, res);
   }
+
   return await res.json();
 }
 
@@ -282,4 +328,6 @@ async function main() {
   }
 }
 
-main();
+if (import.meta.main) {
+  main();
+}