Support nodeUrls (near#733)

src/near.ts

@@ -55,6 +55,12 @@ export interface NearConfig {
      */
     nodeUrl: string;
 
+    /**
+     * NEAR RPC API urls. Compatibility with existing nodeUrl, multiple URLs for JSON RPC calls.
+     * @see {@link JsonRpcProvider.JsonRpcProvider | JsonRpcProvider}
+     */
+    nodeUrls: string;
+
     /**
      * NEAR RPC API headers. Can be used to pass API KEY and other parameters.
      * @see {@link JsonRpcProvider.JsonRpcProvider | JsonRpcProvider}
@@ -82,9 +88,21 @@ export class Near {
 
     constructor(config: NearConfig) {
         this.config = config;
+
+        const nodeUrls = [];
+        if(config.nodeUrl) {
+            nodeUrls.push(config.nodeUrl);
+        }
+        if(config.nodeUrls) {
+            nodeUrls.push(...config.nodeUrls);
+        }
+        if(nodeUrls.length === 0) {
+            throw new Error('Need to pass nodeUrl or nodeUrls.');
+        }
+
         this.connection = Connection.fromConfig({
             networkId: config.networkId,
-            provider: { type: 'JsonRpcProvider', args: { url: config.nodeUrl, headers: config.headers } },
+            provider: { type: 'JsonRpcProvider', args: { selectUrlIndex: 0, urls: nodeUrls, headers: config.headers } },
             signer: config.signer || { type: 'InMemorySigner', keyStore: config.keyStore || (config.deps && config.deps.keyStore) }
         });
         if (config.masterAccount) {

src/providers/json-rpc-provider.ts

@@ -56,14 +56,14 @@ export class JsonRpcProvider extends Provider {
     /**
      * @param connectionInfoOrUrl ConnectionInfo or RPC API endpoint URL (deprecated)
      */
-    constructor(connectionInfoOrUrl?: string | ConnectionInfo) {
+    constructor(connectionInfoOrUrls?: string | ConnectionInfo) {
         super();
-        if (connectionInfoOrUrl != null && typeof connectionInfoOrUrl == 'object') {
-            this.connection = connectionInfoOrUrl as ConnectionInfo;
+        if (connectionInfoOrUrls != null && typeof connectionInfoOrUrls == 'object') {
+            this.connection = connectionInfoOrUrls as ConnectionInfo;
         } else {
             const deprecate = depd('JsonRpcProvider(url?: string)');
             deprecate('use `JsonRpcProvider(connectionInfo: ConnectionInfo)` instead');
-            this.connection = { url: connectionInfoOrUrl as string };
+            this.connection = { selectUrlIndex: 0, urls: [connectionInfoOrUrls as string] };
         }
     }
 

src/utils/web.ts

@@ -9,7 +9,8 @@ const BACKOFF_MULTIPLIER = 1.5;
 const RETRY_NUMBER = 10;
 
 export interface ConnectionInfo {
-    url: string;
+    selectUrlIndex: number;
+    urls: string[];
     user?: string;
     password?: string;
     allowInsecure?: boolean;
@@ -18,38 +19,42 @@ export interface ConnectionInfo {
 }
 
 export async function fetchJson(connectionInfoOrUrl: string | ConnectionInfo, json?: string): Promise<any> {
-    let connectionInfo: ConnectionInfo = { url: null };
+    let connectionInfo: ConnectionInfo = { selectUrlIndex: 0, urls: [] };
+    let selectUrlIndex = 0;
     if (typeof (connectionInfoOrUrl) === 'string') {
-        connectionInfo.url = connectionInfoOrUrl;
+        connectionInfo.urls = [connectionInfoOrUrl];
     } else {
         connectionInfo = connectionInfoOrUrl as ConnectionInfo;
     }
-
     const response = await exponentialBackoff(START_WAIT_TIME_MS, RETRY_NUMBER, BACKOFF_MULTIPLIER, async () => {
+        if(connectionInfo.selectUrlIndex) {
+            selectUrlIndex = connectionInfo.selectUrlIndex;
+        }
+        connectionInfo.selectUrlIndex = (selectUrlIndex + 1) % connectionInfo.urls.length;
         try {
-            const response = await fetch(connectionInfo.url, {
+            const response = await fetch(connectionInfo.urls[selectUrlIndex], {
                 method: json ? 'POST' : 'GET',
                 body: json ? json : undefined,
                 headers: { ...connectionInfo.headers, 'Content-Type': 'application/json' }
             });
             if (!response.ok) {
                 if (response.status === 503) {
-                    logWarning(`Retrying HTTP request for ${connectionInfo.url} as it's not available now`);
+                    logWarning(`Retrying HTTP request for ${connectionInfo.urls[selectUrlIndex]} as it's not available now`);
                     return null;
                 }
                 throw createError(response.status, await response.text());
             }
             return response;
         } catch (error) {
             if (error.toString().includes('FetchError') || error.toString().includes('Failed to fetch')) {
-                logWarning(`Retrying HTTP request for ${connectionInfo.url} because of error: ${error}`);
+                logWarning(`Retrying HTTP request for ${connectionInfo.urls[selectUrlIndex]} because of error: ${error}`);
                 return null;
             }
             throw error;
         }
     });
     if (!response) {
-        throw new TypedError(`Exceeded ${RETRY_NUMBER} attempts for ${connectionInfo.url}.`, 'RetriesExceeded');
+        throw new TypedError(`Exceeded ${RETRY_NUMBER} attempts for ${connectionInfo.urls[selectUrlIndex]}.`, 'RetriesExceeded');
     }
     return await response.json();
 }

test/utils/web.test.js

@@ -14,7 +14,7 @@ describe('web', () => {
         expect(result.result.chain_id).toBe('testnet');
     });
     test('object parameter in fetchJson', async () => {
-        const connection = { url: 'https://rpc.testnet.near.org' };
+        const connection = { urls: ['https://rpc.testnet.near.org'], selectUrlIndex: 0 };
         const statusRequest = {
             'jsonrpc': '2.0',
             'id': 'dontcare',