Add retry429 helper function

The idea is that this provides a generalized way to retry a 429
error, with exponential backoff.

Author: Zloka

src/gcp/retry429.ts

@@ -0,0 +1,23 @@
+import * as clc from "colorette";
+import * as utils from "../utils";
+import { withHttpBackoff } from "./retryWithBackoff";
+
+/**
+ * Convenience wrapper for Cloud Functions deploy operations.
+ * Retries **only** on HTTP 429 and logs a clear message.
+ */
+export function with429Backoff<T>(
+  op: "create" | "update" | "delete" | "generateUploadUrl",
+  resourceName: string,
+  thunk: () => Promise<T>,
+) {
+  return withHttpBackoff(thunk, {
+    statuses: [429],
+    onRetry: ({ attempt, maxAttempts }) => {
+      utils.logLabeledWarning(
+        "functions",
+        `${clc.bold(clc.yellow("429 (Quota Exceeded)"))} on ${op} ${resourceName}; retrying (attempt ${attempt}${maxAttempts ? `/${maxAttempts}` : ""})…`,
+      );
+    },
+  });
+}