Make drandEndpoints configurable

config.example.json

@@ -8,5 +8,10 @@
   "denom": "unois",
   "gasPrice": "0.05unois",
   "prefix": "nois",
-  "moniker": ""
+  "moniker": "",
+  "drandEndpoints": [
+    "https://api2.drand.sh/",
+    "https://api3.drand.sh/",
+    "https://drand.cloudflare.com/"
+  ]
 }

config.ts

@@ -10,4 +10,5 @@ export interface Config {
   readonly gasPrice: string;
   readonly prefix: string;
   readonly moniker: string;
+  readonly drandEndpoints?: string[] | null;
 }

deps.ts

@@ -23,4 +23,9 @@ export type { TendermintClient } from "npm:@cosmjs/tendermint-rpc@^0.31.1";
 
 // drand
 export type { ChainClient, ChainOptions, RandomnessBeacon } from "npm:drand-client@^1.2.0";
-export { FastestNodeClient, watch } from "npm:drand-client@^1.2.0";
+export {
+  FastestNodeClient,
+  HttpCachingChain,
+  HttpChainClient,
+  watch,
+} from "npm:drand-client@^1.2.0";

drand.ts

@@ -4,19 +4,25 @@ export const chainHash = "dbd506d6ef76e5f386f41c651dcb808c5bcbd75471cc4eafa3f4df
 const publicKey =
   "a0b862a7527fee3a731bcb59280ab6abd62d5c0b6ea03dc4ddf6612fdfc9d01f01c31542541771903475eb1ec6615f8d0df0b8b6dce385811d6dcf8cbefb8759e5e616a3dfd054c928940766d9a5b9db91e3b697e5d70a975181e007f87fca5e";
 
+// See https://drand.love/developer/
+// Note that https://api.drand.secureweb3.com:6875 does not support quicknet.
+export const defaultEndpoints = [
+  // `https://api.drand.sh/`,
+  "https://api2.drand.sh/",
+  "https://api3.drand.sh/",
+  "https://drand.cloudflare.com/",
+];
+
 export const drandOptions: ChainOptions = {
   disableBeaconVerification: true,
   noCache: false,
   chainVerificationParams: { chainHash, publicKey },
 };
 
-export const drandUrls = [
-  // `https://api.drand.sh/${chainHash}`,
-  `https://api2.drand.sh/${chainHash}`,
-  `https://api3.drand.sh/${chainHash}`,
-  `https://drand.cloudflare.com/${chainHash}`,
-  // ...
-];
+/** Appends the chain hash to the endpoint */
+export function drandBaseUrl(endpoint: string): string {
+  return endpoint.replace(/\/$/, "") + "/" + chainHash;
+}
 
 // https://api3.drand.sh/dbd506d6ef76e5f386f41c651dcb808c5bcbd75471cc4eafa3f4df7ad4e4c493/info
 const DRAND_GENESIS = 1677685200;

main.ts

@@ -1,14 +1,23 @@
-import { drandOptions, drandUrls, publishedIn, publishedSince } from "./drand.ts";
+import {
+  defaultEndpoints,
+  drandBaseUrl,
+  drandOptions,
+  publishedIn,
+  publishedSince,
+} from "./drand.ts";
 import { group } from "./group.ts";
 import {
   assert,
   calculateFee,
+  ChainClient,
   Coin,
   CosmWasmClient,
   Decimal,
   DirectSecp256k1HdWallet,
   FastestNodeClient,
   GasPrice,
+  HttpCachingChain,
+  HttpChainClient,
   SignerData,
   SigningCosmWasmClient,
   sleep,
@@ -146,7 +155,22 @@ if (import.meta.main) {
 
   const incentivizedRounds = new Map<number, Promise<boolean>>();
 
-  const fastestNodeClient = new FastestNodeClient(drandUrls, drandOptions);
+  const drandEndpoints = config.drandEndpoints ?? defaultEndpoints;
+  assert(
+    drandEndpoints,
+    "drandEndpoints must not be an empty list. Use null or omit to use the default list.",
+  );
+
+  const drandClient: ChainClient = (() => {
+    if (drandEndpoints.length === 1) {
+      const chain = new HttpCachingChain(drandBaseUrl(drandEndpoints[0]), drandOptions);
+      return new HttpChainClient(chain);
+    } else {
+      const fc = new FastestNodeClient(drandEndpoints.map(drandBaseUrl), drandOptions);
+      fc.start();
+      return fc;
+    }
+  })();
 
   const submitter = new Submitter({
     client,
@@ -160,12 +184,11 @@ if (import.meta.main) {
     drandAddress: drandAddress,
     userAgent,
     incentivizedRounds,
-    drandClient: fastestNodeClient,
+    drandClient,
   });
 
-  fastestNodeClient.start();
   const abortController = new AbortController();
-  for await (const beacon of watch(fastestNodeClient, abortController)) {
+  for await (const beacon of watch(drandClient, abortController)) {
     const n = beacon.round; // n is the round we just received and process now
     const m = n + 1; // m := n+1 refers to the next round in this current loop
 

submitter.ts

@@ -3,8 +3,8 @@ import { publishedSince, timeOfRound } from "./drand.ts";
 import {
   assertIsDeliverTxSuccess,
   calculateFee,
+  ChainClient,
   CosmWasmClient,
-  FastestNodeClient,
   isDefined,
   logs,
   RandomnessBeacon,
@@ -28,7 +28,7 @@ interface Capture {
   userAgent: string;
   getNextSignData: () => SignerData;
   incentivizedRounds: Map<number, Promise<boolean>>;
-  drandClient: FastestNodeClient;
+  drandClient: ChainClient;
 }
 
 export class Submitter {