From 1f7c47785cdae473a12c842d555dffa001a543c4 Mon Sep 17 00:00:00 2001
From: Serhii Volovyk <sergeyvolovyk@gmail.com>
Date: Mon, 20 Dec 2021 23:51:36 +0200
Subject: [PATCH 01/10] multiple API Keys support added to provider

---
 examples/cookbook/api-keys/provider-example.js | 5 ++---
 lib/utils/web.d.ts                             | 3 +++
 lib/utils/web.js                               | 6 +++++-
 src/utils/web.ts                               | 7 ++++++-
 4 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/examples/cookbook/api-keys/provider-example.js b/examples/cookbook/api-keys/provider-example.js
index 34ce9ad044..7710e76fdb 100644
--- a/examples/cookbook/api-keys/provider-example.js
+++ b/examples/cookbook/api-keys/provider-example.js
@@ -1,12 +1,11 @@
 // demonstrates how to use API-KEY with provider 
 const { providers } = require("near-api-js");
 
-const RPC_API_ENDPOINT = '<Replace this string with your RPC server URL>';
 const API_KEY = '<Replace this string with your API KEY>';
 
 const provider = new providers.JsonRpcProvider({
-    url: RPC_API_ENDPOINT,
-    headers: { 'x-api-key': API_KEY },
+    url: 'https://testnet.rpc.near.dev',
+    apiKeys: { 'https://testnet.rpc.near.dev': API_KEY }
 });
 
 getNetworkStatus();
diff --git a/lib/utils/web.d.ts b/lib/utils/web.d.ts
index 639cb740ea..fbf76af030 100644
--- a/lib/utils/web.d.ts
+++ b/lib/utils/web.d.ts
@@ -1,5 +1,8 @@
 export interface ConnectionInfo {
     url: string;
+    apiKeys?: {
+        [url: string]: string;
+    };
     user?: string;
     password?: string;
     allowInsecure?: boolean;
diff --git a/lib/utils/web.js b/lib/utils/web.js
index 2cd5a75c8b..476846acba 100644
--- a/lib/utils/web.js
+++ b/lib/utils/web.js
@@ -24,7 +24,11 @@ async function fetchJson(connectionInfoOrUrl, json) {
             const response = await fetch(connectionInfo.url, {
                 method: json ? 'POST' : 'GET',
                 body: json ? json : undefined,
-                headers: { ...connectionInfo.headers, 'Content-Type': 'application/json' }
+                headers: {
+                    'Content-Type': 'application/json',
+                    'x-api-key': connectionInfo.apiKeys ? connectionInfo.apiKeys[connectionInfo.url] : undefined,
+                    ...connectionInfo.headers,
+                },
             });
             if (!response.ok) {
                 if (response.status === 503) {
diff --git a/src/utils/web.ts b/src/utils/web.ts
index 8e8dfe6a15..e6dbc9b638 100644
--- a/src/utils/web.ts
+++ b/src/utils/web.ts
@@ -10,6 +10,7 @@ const RETRY_NUMBER = 10;
 
 export interface ConnectionInfo {
     url: string;
+    apiKeys?: { [url: string]: string }
     user?: string;
     password?: string;
     allowInsecure?: boolean;
@@ -30,7 +31,11 @@ export async function fetchJson(connectionInfoOrUrl: string | ConnectionInfo, js
             const response = await fetch(connectionInfo.url, {
                 method: json ? 'POST' : 'GET',
                 body: json ? json : undefined,
-                headers: { ...connectionInfo.headers, 'Content-Type': 'application/json' }
+                headers: {
+                    'Content-Type': 'application/json',
+                    'x-api-key': connectionInfo.apiKeys ? connectionInfo.apiKeys[connectionInfo.url] : undefined,
+                    ...connectionInfo.headers,
+                },
             });
             if (!response.ok) {
                 if (response.status === 503) {

From 35c70a6c254ff1c2464470b79590dccbc2da65bc Mon Sep 17 00:00:00 2001
From: Serhii Volovyk <sergeyvolovyk@gmail.com>
Date: Tue, 21 Dec 2021 00:41:49 +0200
Subject: [PATCH 02/10] multiple api keys support added to the top level API

---
 examples/cookbook/api-keys/near-connection.js |  7 +++----
 lib/near.d.ts                                 |  4 ++++
 lib/near.js                                   |  8 +++++++-
 src/near.ts                                   | 13 +++++++++++--
 4 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/examples/cookbook/api-keys/near-connection.js b/examples/cookbook/api-keys/near-connection.js
index d263241461..b255169012 100644
--- a/examples/cookbook/api-keys/near-connection.js
+++ b/examples/cookbook/api-keys/near-connection.js
@@ -7,16 +7,15 @@ const CREDENTIALS_DIR = ".near-credentials";
 const credentialsPath = path.join(homedir, CREDENTIALS_DIR);
 const keyStore = new keyStores.UnencryptedFileSystemKeyStore(credentialsPath);
 
-const RPC_API_ENDPOINT = '<Replace this string with your RPC server URL>';
 const API_KEY = '<Replace this string with your API KEY>';
-
 const ACCOUNT_ID = '<Replace this string with existing account ID>';
 
 const config = {
     networkId: 'testnet',
     keyStore,
-    nodeUrl: RPC_API_ENDPOINT,
-    headers: { 'x-api-key': API_KEY },
+    nodeUrl: '<Replace this string with your RPC server URL>',
+    // RPC server URL in apiKeys should match the one specified in nodeUrl
+    apiKeys: { '<Replace this string with your RPC server URL>': API_KEY },
 };
 
 async function getState(accountId) {
diff --git a/lib/near.d.ts b/lib/near.d.ts
index 939162f8fa..5152a16da6 100644
--- a/lib/near.d.ts
+++ b/lib/near.d.ts
@@ -48,6 +48,10 @@ export interface NearConfig {
      * @see {@link JsonRpcProvider.JsonRpcProvider | JsonRpcProvider}
      */
     nodeUrl: string;
+    /**
+     * RPC API Keys. Used to authenticate users on RPC Server.
+     */
+    apiKeys: string;
     /**
      * NEAR RPC API headers. Can be used to pass API KEY and other parameters.
      * @see {@link JsonRpcProvider.JsonRpcProvider | JsonRpcProvider}
diff --git a/lib/near.js b/lib/near.js
index c74bce98a0..1d09c0379b 100644
--- a/lib/near.js
+++ b/lib/near.js
@@ -30,7 +30,13 @@ class Near {
         this.config = config;
         this.connection = connection_1.Connection.fromConfig({
             networkId: config.networkId,
-            provider: { type: 'JsonRpcProvider', args: { url: config.nodeUrl, headers: config.headers } },
+            provider: {
+                type: 'JsonRpcProvider', args: {
+                    url: config.nodeUrl,
+                    apiKeys: config.apiKeys,
+                    headers: config.headers,
+                }
+            },
             signer: config.signer || { type: 'InMemorySigner', keyStore: config.keyStore || (config.deps && config.deps.keyStore) }
         });
         if (config.masterAccount) {
diff --git a/src/near.ts b/src/near.ts
index aeb7c9facb..70195484fc 100644
--- a/src/near.ts
+++ b/src/near.ts
@@ -54,7 +54,10 @@ export interface NearConfig {
      * @see {@link JsonRpcProvider.JsonRpcProvider | JsonRpcProvider}
      */
     nodeUrl: string;
-
+    /**
+     * RPC API Keys. Used to authenticate users on RPC Server.
+     */
+    apiKeys: string;
     /**
      * NEAR RPC API headers. Can be used to pass API KEY and other parameters.
      * @see {@link JsonRpcProvider.JsonRpcProvider | JsonRpcProvider}
@@ -84,7 +87,13 @@ export class Near {
         this.config = config;
         this.connection = Connection.fromConfig({
             networkId: config.networkId,
-            provider: { type: 'JsonRpcProvider', args: { url: config.nodeUrl, headers: config.headers } },
+            provider: {
+                type: 'JsonRpcProvider', args: {
+                    url: config.nodeUrl,
+                    apiKeys: config.apiKeys,
+                    headers: config.headers,
+                }
+            },
             signer: config.signer || { type: 'InMemorySigner', keyStore: config.keyStore || (config.deps && config.deps.keyStore) }
         });
         if (config.masterAccount) {

From 952558e8af8a5da6022ff7c767a0290293f96ff2 Mon Sep 17 00:00:00 2001
From: Serhii Volovyk <sergeyvolovyk@gmail.com>
Date: Tue, 21 Dec 2021 00:45:32 +0200
Subject: [PATCH 03/10] links replaced with placeholders

---
 examples/cookbook/api-keys/provider-example.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/examples/cookbook/api-keys/provider-example.js b/examples/cookbook/api-keys/provider-example.js
index 7710e76fdb..c0dcb932a5 100644
--- a/examples/cookbook/api-keys/provider-example.js
+++ b/examples/cookbook/api-keys/provider-example.js
@@ -4,8 +4,8 @@ const { providers } = require("near-api-js");
 const API_KEY = '<Replace this string with your API KEY>';
 
 const provider = new providers.JsonRpcProvider({
-    url: 'https://testnet.rpc.near.dev',
-    apiKeys: { 'https://testnet.rpc.near.dev': API_KEY }
+    url: '<Replace this string with your RPC server URL>',
+    apiKeys: { '<Replace this string with your RPC server URL>': API_KEY }
 });
 
 getNetworkStatus();

From 2ec72007eeda14dbdff0e3509aa88fc254ca343d Mon Sep 17 00:00:00 2001
From: Serhii Volovyk <sergeyvolovyk@gmail.com>
Date: Tue, 21 Dec 2021 00:48:37 +0200
Subject: [PATCH 04/10] added disclaimer

---
 examples/cookbook/api-keys/provider-example.js | 1 +
 1 file changed, 1 insertion(+)

diff --git a/examples/cookbook/api-keys/provider-example.js b/examples/cookbook/api-keys/provider-example.js
index c0dcb932a5..2338991b0a 100644
--- a/examples/cookbook/api-keys/provider-example.js
+++ b/examples/cookbook/api-keys/provider-example.js
@@ -5,6 +5,7 @@ const API_KEY = '<Replace this string with your API KEY>';
 
 const provider = new providers.JsonRpcProvider({
     url: '<Replace this string with your RPC server URL>',
+    // RPC server URL in apiKeys should match the one specified in url
     apiKeys: { '<Replace this string with your RPC server URL>': API_KEY }
 });
 

From 2cdb754aa195f38f974c2757825e95b652d763fa Mon Sep 17 00:00:00 2001
From: Serhii Volovyk <sergeyvolovyk@gmail.com>
Date: Thu, 23 Dec 2021 17:49:58 +0200
Subject: [PATCH 05/10] example added

---
 examples/cookbook/failover-configuration.js | 25 +++++++++++++++++++++
 src/providers/json-rpc-provider.ts          |  2 +-
 src/utils/web.ts                            |  1 +
 3 files changed, 27 insertions(+), 1 deletion(-)
 create mode 100644 examples/cookbook/failover-configuration.js

diff --git a/examples/cookbook/failover-configuration.js b/examples/cookbook/failover-configuration.js
new file mode 100644
index 0000000000..3819269a62
--- /dev/null
+++ b/examples/cookbook/failover-configuration.js
@@ -0,0 +1,25 @@
+// Demonstrates how to use failover functionality with provider 
+const { providers } = require("near-api-js");
+
+//TODO: replace with placeholders
+const MAIN_RPC_SERVER = 'https://rpc.testnet.near.org';
+const FAILOVER_RPC_SERVER_1 = 'https://rpc.ci-testnet.near.org';
+const FAILOVER_RPC_SERVER_2 = 'https://testnet.rpc.near.dev'; //this one needs API Key
+
+// Provider example
+const provider = new providers.JsonRpcProvider({
+    url: MAIN_RPC_SERVER,
+    /* In case of several unsuccessful calls to the main RPC Server,
+    near-api-js will make an attempt to execute call on failover RPC servers. */
+    failoverUrls: [FAILOVER_RPC_SERVER_1, FAILOVER_RPC_SERVER_2],
+});
+
+async function getNetworkStatus() {
+    const result = await provider.status();
+    console.log(result);
+}
+
+getNetworkStatus();
+
+// Connection example
+//TODO⏎
\ No newline at end of file
diff --git a/src/providers/json-rpc-provider.ts b/src/providers/json-rpc-provider.ts
index 64204630eb..227521f548 100644
--- a/src/providers/json-rpc-provider.ts
+++ b/src/providers/json-rpc-provider.ts
@@ -379,7 +379,7 @@ export class JsonRpcProvider extends Provider {
                 return response;
             } catch (error) {
                 if (error.type === 'TimeoutError') {
-                    if (!process.env['NEAR_NO_LOGS']){
+                    if (!process.env['NEAR_NO_LOGS']) {
                         console.warn(`Retrying request to ${method} as it has timed out`, params);
                     }
                     return null;
diff --git a/src/utils/web.ts b/src/utils/web.ts
index e6dbc9b638..257a58bbe6 100644
--- a/src/utils/web.ts
+++ b/src/utils/web.ts
@@ -10,6 +10,7 @@ const RETRY_NUMBER = 10;
 
 export interface ConnectionInfo {
     url: string;
+    failoverRpcUrls?: string[],
     apiKeys?: { [url: string]: string }
     user?: string;
     password?: string;

From 93584a06daaa0e650482b254486489c7bcf56aa4 Mon Sep 17 00:00:00 2001
From: Serhii Volovyk <sergeyvolovyk@gmail.com>
Date: Thu, 23 Dec 2021 18:45:21 +0200
Subject: [PATCH 06/10] RPC server rotation function added

---
 examples/cookbook/failover-configuration.js |  6 ++----
 lib/providers/json-rpc-provider.d.ts        |  5 +++++
 lib/providers/json-rpc-provider.js          | 12 ++++++++++++
 lib/utils/web.d.ts                          |  2 +-
 lib/utils/web.js                            | 11 ++++++-----
 src/providers/json-rpc-provider.ts          | 11 +++++++++++
 src/utils/web.ts                            | 16 +++++++++-------
 7 files changed, 46 insertions(+), 17 deletions(-)

diff --git a/examples/cookbook/failover-configuration.js b/examples/cookbook/failover-configuration.js
index 3819269a62..b32f9a9087 100644
--- a/examples/cookbook/failover-configuration.js
+++ b/examples/cookbook/failover-configuration.js
@@ -8,10 +8,8 @@ const FAILOVER_RPC_SERVER_2 = 'https://testnet.rpc.near.dev'; //this one needs A
 
 // Provider example
 const provider = new providers.JsonRpcProvider({
-    url: MAIN_RPC_SERVER,
-    /* In case of several unsuccessful calls to the main RPC Server,
-    near-api-js will make an attempt to execute call on failover RPC servers. */
-    failoverUrls: [FAILOVER_RPC_SERVER_1, FAILOVER_RPC_SERVER_2],
+    // TODO: what is happening here
+    url: [MAIN_RPC_SERVER, FAILOVER_RPC_SERVER_1, FAILOVER_RPC_SERVER_2],
 });
 
 async function getNetworkStatus() {
diff --git a/lib/providers/json-rpc-provider.d.ts b/lib/providers/json-rpc-provider.d.ts
index ba97db325d..e3a1970d86 100644
--- a/lib/providers/json-rpc-provider.d.ts
+++ b/lib/providers/json-rpc-provider.d.ts
@@ -155,6 +155,11 @@ export declare class JsonRpcProvider extends Provider {
      * @param blockId Block hash or height, or null for latest.
      */
     gasPrice(blockId: BlockId | null): Promise<GasPrice>;
+    /**
+     * Part of the RPC failover design.
+     * Changing current (first) rpc server and moves it to the and of the queue.
+     */
+    private rotateRpcServers;
     /**
      * Directly call the RPC specifying the method and params
      *
diff --git a/lib/providers/json-rpc-provider.js b/lib/providers/json-rpc-provider.js
index c4fb1c2623..39a68c305e 100644
--- a/lib/providers/json-rpc-provider.js
+++ b/lib/providers/json-rpc-provider.js
@@ -294,6 +294,16 @@ class JsonRpcProvider extends provider_1.Provider {
     async gasPrice(blockId) {
         return await this.sendJsonRpc('gas_price', [blockId]);
     }
+    /**
+     * Part of the RPC failover design.
+     * Changing current (first) rpc server and moves it to the and of the queue.
+     */
+    rotateRpcServers() {
+        if (typeof this.connection.url === 'string') {
+            return;
+        }
+        this.connection.url.push(this.connection.url.shift());
+    }
     /**
      * Directly call the RPC specifying the method and params
      *
@@ -337,6 +347,8 @@ class JsonRpcProvider extends provider_1.Provider {
                     if (!process.env['NEAR_NO_LOGS']) {
                         console.warn(`Retrying request to ${method} as it has timed out`, params);
                     }
+                    // switch  to another server if it's available
+                    this.rotateRpcServers();
                     return null;
                 }
                 throw error;
diff --git a/lib/utils/web.d.ts b/lib/utils/web.d.ts
index fbf76af030..5ceb9e457d 100644
--- a/lib/utils/web.d.ts
+++ b/lib/utils/web.d.ts
@@ -1,5 +1,5 @@
 export interface ConnectionInfo {
-    url: string;
+    url: string | string[];
     apiKeys?: {
         [url: string]: string;
     };
diff --git a/lib/utils/web.js b/lib/utils/web.js
index 476846acba..2a3198005a 100644
--- a/lib/utils/web.js
+++ b/lib/utils/web.js
@@ -19,20 +19,21 @@ async function fetchJson(connectionInfoOrUrl, json) {
     else {
         connectionInfo = connectionInfoOrUrl;
     }
+    const currentRpcServer = typeof connectionInfo.url === 'string' ? connectionInfo.url : connectionInfo.url[0];
     const response = await exponential_backoff_1.default(START_WAIT_TIME_MS, RETRY_NUMBER, BACKOFF_MULTIPLIER, async () => {
         try {
-            const response = await fetch(connectionInfo.url, {
+            const response = await fetch(currentRpcServer, {
                 method: json ? 'POST' : 'GET',
                 body: json ? json : undefined,
                 headers: {
                     'Content-Type': 'application/json',
-                    'x-api-key': connectionInfo.apiKeys ? connectionInfo.apiKeys[connectionInfo.url] : undefined,
+                    'x-api-key': connectionInfo.apiKeys ? connectionInfo.apiKeys[currentRpcServer] : undefined,
                     ...connectionInfo.headers,
                 },
             });
             if (!response.ok) {
                 if (response.status === 503) {
-                    errors_1.logWarning(`Retrying HTTP request for ${connectionInfo.url} as it's not available now`);
+                    errors_1.logWarning(`Retrying HTTP request for ${currentRpcServer} as it's not available now`);
                     return null;
                 }
                 throw http_errors_1.default(response.status, await response.text());
@@ -41,14 +42,14 @@ async function fetchJson(connectionInfoOrUrl, json) {
         }
         catch (error) {
             if (error.toString().includes('FetchError') || error.toString().includes('Failed to fetch')) {
-                errors_1.logWarning(`Retrying HTTP request for ${connectionInfo.url} because of error: ${error}`);
+                errors_1.logWarning(`Retrying HTTP request for ${currentRpcServer} because of error: ${error}`);
                 return null;
             }
             throw error;
         }
     });
     if (!response) {
-        throw new providers_1.TypedError(`Exceeded ${RETRY_NUMBER} attempts for ${connectionInfo.url}.`, 'RetriesExceeded');
+        throw new providers_1.TypedError(`Exceeded ${RETRY_NUMBER} attempts for ${currentRpcServer}.`, 'RetriesExceeded');
     }
     return await response.json();
 }
diff --git a/src/providers/json-rpc-provider.ts b/src/providers/json-rpc-provider.ts
index 227521f548..6a1a067e4b 100644
--- a/src/providers/json-rpc-provider.ts
+++ b/src/providers/json-rpc-provider.ts
@@ -339,6 +339,15 @@ export class JsonRpcProvider extends Provider {
         return await this.sendJsonRpc('gas_price', [blockId]);
     }
 
+    /**
+     * Part of the RPC failover design.
+     * Changing current (first) rpc server and moves it to the and of the queue.
+     */
+    private rotateRpcServers() {
+        if (typeof this.connection.url === 'string') { return; }
+        this.connection.url.push(this.connection.url.shift());
+    }
+
     /**
      * Directly call the RPC specifying the method and params
      *
@@ -382,6 +391,8 @@ export class JsonRpcProvider extends Provider {
                     if (!process.env['NEAR_NO_LOGS']) {
                         console.warn(`Retrying request to ${method} as it has timed out`, params);
                     }
+                    // switch  to another server if it's available
+                    this.rotateRpcServers();
                     return null;
                 }
 
diff --git a/src/utils/web.ts b/src/utils/web.ts
index 257a58bbe6..60c45f0351 100644
--- a/src/utils/web.ts
+++ b/src/utils/web.ts
@@ -9,8 +9,8 @@ const BACKOFF_MULTIPLIER = 1.5;
 const RETRY_NUMBER = 10;
 
 export interface ConnectionInfo {
-    url: string;
-    failoverRpcUrls?: string[],
+    // RPC Server URL or the prioritized array of such URLs
+    url: string | string[];
     apiKeys?: { [url: string]: string }
     user?: string;
     password?: string;
@@ -27,20 +27,22 @@ export async function fetchJson(connectionInfoOrUrl: string | ConnectionInfo, js
         connectionInfo = connectionInfoOrUrl as ConnectionInfo;
     }
 
+    const currentRpcServer = typeof connectionInfo.url === 'string' ? connectionInfo.url : connectionInfo.url[0];
+
     const response = await exponentialBackoff(START_WAIT_TIME_MS, RETRY_NUMBER, BACKOFF_MULTIPLIER, async () => {
         try {
-            const response = await fetch(connectionInfo.url, {
+            const response = await fetch(currentRpcServer, {
                 method: json ? 'POST' : 'GET',
                 body: json ? json : undefined,
                 headers: {
                     'Content-Type': 'application/json',
-                    'x-api-key': connectionInfo.apiKeys ? connectionInfo.apiKeys[connectionInfo.url] : undefined,
+                    'x-api-key': connectionInfo.apiKeys ? connectionInfo.apiKeys[currentRpcServer] : undefined,
                     ...connectionInfo.headers,
                 },
             });
             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 ${currentRpcServer} as it's not available now`);
                     return null;
                 }
                 throw createError(response.status, await response.text());
@@ -48,14 +50,14 @@ export async function fetchJson(connectionInfoOrUrl: string | ConnectionInfo, js
             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 ${currentRpcServer} 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 ${currentRpcServer}.`, 'RetriesExceeded');
     }
     return await response.json();
 }

From fb77268e81e770498f7bb1f35ab0d5344e4ca1c1 Mon Sep 17 00:00:00 2001
From: Serhii Volovyk <sergeyvolovyk@gmail.com>
Date: Thu, 23 Dec 2021 18:49:28 +0200
Subject: [PATCH 07/10] added console logs for server rotation

---
 lib/providers/json-rpc-provider.js | 6 +++++-
 src/providers/json-rpc-provider.ts | 6 +++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/lib/providers/json-rpc-provider.js b/lib/providers/json-rpc-provider.js
index 39a68c305e..6a06219ab1 100644
--- a/lib/providers/json-rpc-provider.js
+++ b/lib/providers/json-rpc-provider.js
@@ -302,7 +302,11 @@ class JsonRpcProvider extends provider_1.Provider {
         if (typeof this.connection.url === 'string') {
             return;
         }
-        this.connection.url.push(this.connection.url.shift());
+        const currentRpcServer = this.connection.url.shift();
+        this.connection.url.push(currentRpcServer);
+        if (!process.env['NEAR_NO_LOGS']) {
+            console.warn(`Switched from ${currentRpcServer} RPC Server to ${this.connection.url[0]}`);
+        }
     }
     /**
      * Directly call the RPC specifying the method and params
diff --git a/src/providers/json-rpc-provider.ts b/src/providers/json-rpc-provider.ts
index 6a1a067e4b..404671ffe7 100644
--- a/src/providers/json-rpc-provider.ts
+++ b/src/providers/json-rpc-provider.ts
@@ -345,7 +345,11 @@ export class JsonRpcProvider extends Provider {
      */
     private rotateRpcServers() {
         if (typeof this.connection.url === 'string') { return; }
-        this.connection.url.push(this.connection.url.shift());
+        const currentRpcServer = this.connection.url.shift();
+        this.connection.url.push(currentRpcServer);
+        if (!process.env['NEAR_NO_LOGS']) {
+            console.warn(`Switched from ${currentRpcServer} RPC Server to ${this.connection.url[0]}`);
+        }
     }
 
     /**

From f2c92f554e3cfbcc825acca1beb7f2940c9cb094 Mon Sep 17 00:00:00 2001
From: Serhii Volovyk <sergeyvolovyk@gmail.com>
Date: Thu, 23 Dec 2021 18:56:38 +0200
Subject: [PATCH 08/10] RPC Server rotation function test added

---
 test/providers.test.js | 34 +++++++++++++++++++++++++---------
 1 file changed, 25 insertions(+), 9 deletions(-)

diff --git a/test/providers.test.js b/test/providers.test.js
index 730763d879..3b11912c02 100644
--- a/test/providers.test.js
+++ b/test/providers.test.js
@@ -1,5 +1,5 @@
 const nearApi = require('../src/index');
-const testUtils  = require('./test-utils');
+const testUtils = require('./test-utils');
 const BN = require('bn.js');
 const base58 = require('bs58');
 
@@ -64,7 +64,7 @@ test('json rpc fetch validators info', withProvider(async (provider) => {
     expect(validators.current_validators.length).toBeGreaterThanOrEqual(1);
 }));
 
-test('txStatus with string hash and buffer hash', withProvider(async(provider) => {
+test('txStatus with string hash and buffer hash', withProvider(async (provider) => {
     const near = await testUtils.setUpTestConnection();
     const sender = await testUtils.createAccount(near);
     const receiver = await testUtils.createAccount(near);
@@ -76,7 +76,7 @@ test('txStatus with string hash and buffer hash', withProvider(async(provider) =
     expect(responseWithUint8Array).toMatchObject(outcome);
 }));
 
-test('json rpc query with block_id', withProvider(async(provider) => {
+test('json rpc query with block_id', withProvider(async (provider) => {
     const stat = await provider.status();
     let block_id = stat.sync_info.latest_block_height - 1;
 
@@ -111,7 +111,7 @@ test('json rpc query view_state', withProvider(async (provider) => {
 
     await contract.setValue({ args: { value: 'hello' } });
 
-    return testUtils.waitFor(async() => {
+    return testUtils.waitFor(async () => {
         const response = await provider.query({
             request_type: 'view_state',
             finality: 'final',
@@ -152,7 +152,7 @@ test('json rpc query view_code', withProvider(async (provider) => {
     const account = await testUtils.createAccount(near);
     const contract = await testUtils.deployContract(account, testUtils.generateUniqueString('test'));
 
-    return testUtils.waitFor(async() => {
+    return testUtils.waitFor(async () => {
         const response = await provider.query({
             request_type: 'view_code',
             finality: 'final',
@@ -175,7 +175,7 @@ test('json rpc query call_function', withProvider(async (provider) => {
 
     await contract.setValue({ args: { value: 'hello' } });
 
-    return testUtils.waitFor(async() => {
+    return testUtils.waitFor(async () => {
         const response = await provider.query({
             request_type: 'call_function',
             finality: 'final',
@@ -200,7 +200,7 @@ test('json rpc query call_function', withProvider(async (provider) => {
     });
 }));
 
-test('final tx result', async() => {
+test('final tx result', async () => {
     const result = {
         status: { SuccessValue: 'e30=' },
         transaction: { id: '11111', outcome: { status: { SuccessReceiptId: '11112' }, logs: [], receipt_ids: ['11112'], gas_burnt: 1 } },
@@ -212,7 +212,7 @@ test('final tx result', async() => {
     expect(nearApi.providers.getTransactionLastResult(result)).toEqual({});
 });
 
-test('final tx result with null', async() => {
+test('final tx result with null', async () => {
     const result = {
         status: 'Failure',
         transaction: { id: '11111', outcome: { status: { SuccessReceiptId: '11112' }, logs: [], receipt_ids: ['11112'], gas_burnt: 1 } },
@@ -224,7 +224,7 @@ test('final tx result with null', async() => {
     expect(nearApi.providers.getTransactionLastResult(result)).toEqual(null);
 });
 
-test('json rpc light client proof', async() => {
+test('json rpc light client proof', async () => {
     const near = await testUtils.setUpTestConnection();
     const workingAccount = await testUtils.createAccount(near);
     const executionOutcome = await workingAccount.sendMoney(workingAccount.accountId, new BN(10000));
@@ -335,4 +335,20 @@ test('near json rpc fetch node status', async () => {
     const near = await nearApi.connect(config);
     let response = await near.connection.provider.status();
     expect(response.chain_id).toBeTruthy();
+});
+
+test('JsonRpc rotateRpcServers', async () => {
+    const SERVER_1 = "server1";
+    const SERVER_2 = "server2";
+    const SERVER_3 = "server3";
+    const provider = new nearApi.providers.JsonRpcProvider({ url: [SERVER_1, SERVER_2, SERVER_3] });
+    expect(provider.connection.url.length).toEqual(3);
+    expect(provider.connection.url[0]).toMatch(SERVER_1);
+    expect(provider.connection.url[1]).toMatch(SERVER_2);
+    expect(provider.connection.url[2]).toMatch(SERVER_3);
+    provider.rotateRpcServers();
+    expect(provider.connection.url.length).toEqual(3);
+    expect(provider.connection.url[0]).toMatch(SERVER_2);
+    expect(provider.connection.url[1]).toMatch(SERVER_3);
+    expect(provider.connection.url[2]).toMatch(SERVER_1);
 });
\ No newline at end of file

From 1b557dc363f52e55a7cdc49cdfc7cb0087c81c69 Mon Sep 17 00:00:00 2001
From: Serhii Volovyk <sergeyvolovyk@gmail.com>
Date: Thu, 23 Dec 2021 19:20:32 +0200
Subject: [PATCH 09/10] connection example added

---
 examples/cookbook/failover-configuration.js | 29 +++++++++++++++------
 lib/near.d.ts                               |  5 ++--
 src/near.ts                                 |  7 +++--
 3 files changed, 29 insertions(+), 12 deletions(-)

diff --git a/examples/cookbook/failover-configuration.js b/examples/cookbook/failover-configuration.js
index b32f9a9087..ba60185ef3 100644
--- a/examples/cookbook/failover-configuration.js
+++ b/examples/cookbook/failover-configuration.js
@@ -1,14 +1,13 @@
-// Demonstrates how to use failover functionality with provider 
-const { providers } = require("near-api-js");
+// Demonstrates how to use failover functionality RPC Servers
+const { providers, connect } = require("near-api-js");
 
-//TODO: replace with placeholders
-const MAIN_RPC_SERVER = 'https://rpc.testnet.near.org';
-const FAILOVER_RPC_SERVER_1 = 'https://rpc.ci-testnet.near.org';
-const FAILOVER_RPC_SERVER_2 = 'https://testnet.rpc.near.dev'; //this one needs API Key
+const MAIN_RPC_SERVER = '<RPC Server 1>';
+const FAILOVER_RPC_SERVER_1 = '<RPC Server 2>';
+const FAILOVER_RPC_SERVER_2 = '<RPC Server 1>';
 
 // Provider example
 const provider = new providers.JsonRpcProvider({
-    // TODO: what is happening here
+    // preoritized list of RPC Servers
     url: [MAIN_RPC_SERVER, FAILOVER_RPC_SERVER_1, FAILOVER_RPC_SERVER_2],
 });
 
@@ -20,4 +19,18 @@ async function getNetworkStatus() {
 getNetworkStatus();
 
 // Connection example
-//TODO⏎
\ No newline at end of file
+const ACCOUNT_ID = "<Account ID>";
+
+const config = {
+    networkId: 'testnet',
+    nodeUrl: [MAIN_RPC_SERVER, FAILOVER_RPC_SERVER_1, FAILOVER_RPC_SERVER_2],
+};
+
+async function getState(accountId) {
+    const near = await connect(config);
+    const account = await near.account(accountId);
+    const state = await account.state();
+    console.log(state);
+}
+
+getState(ACCOUNT_ID);
\ No newline at end of file
diff --git a/lib/near.d.ts b/lib/near.d.ts
index 5152a16da6..1aa6dd6ef3 100644
--- a/lib/near.d.ts
+++ b/lib/near.d.ts
@@ -44,10 +44,11 @@ export interface NearConfig {
      */
     networkId: string;
     /**
-     * NEAR RPC API url. used to make JSON RPC calls to interact with NEAR.
+     * NEAR RPC API url. Used to make JSON RPC calls to interact with NEAR.
+     * You can set multiple RPC Server URLs to turn on failover functionality.
      * @see {@link JsonRpcProvider.JsonRpcProvider | JsonRpcProvider}
      */
-    nodeUrl: string;
+    nodeUrl: string | string[];
     /**
      * RPC API Keys. Used to authenticate users on RPC Server.
      */
diff --git a/src/near.ts b/src/near.ts
index 70195484fc..a7b278d8fc 100644
--- a/src/near.ts
+++ b/src/near.ts
@@ -50,14 +50,17 @@ export interface NearConfig {
     networkId: string;
 
     /**
-     * NEAR RPC API url. used to make JSON RPC calls to interact with NEAR.
+     * NEAR RPC API url. Used to make JSON RPC calls to interact with NEAR.
+     * You can set multiple RPC Server URLs to turn on failover functionality.
      * @see {@link JsonRpcProvider.JsonRpcProvider | JsonRpcProvider}
      */
-    nodeUrl: string;
+    nodeUrl: string | string[];
+
     /**
      * RPC API Keys. Used to authenticate users on RPC Server.
      */
     apiKeys: string;
+
     /**
      * NEAR RPC API headers. Can be used to pass API KEY and other parameters.
      * @see {@link JsonRpcProvider.JsonRpcProvider | JsonRpcProvider}

From da0085299cd6d5bd73aa2f577bad59eec0d6f9cb Mon Sep 17 00:00:00 2001
From: Serhii Volovyk <sergeyvolovyk@gmail.com>
Date: Thu, 23 Dec 2021 19:33:02 +0200
Subject: [PATCH 10/10] lint

---
 src/utils/web.ts       | 2 +-
 test/providers.test.js | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/utils/web.ts b/src/utils/web.ts
index 60c45f0351..87da66a844 100644
--- a/src/utils/web.ts
+++ b/src/utils/web.ts
@@ -11,7 +11,7 @@ const RETRY_NUMBER = 10;
 export interface ConnectionInfo {
     // RPC Server URL or the prioritized array of such URLs
     url: string | string[];
-    apiKeys?: { [url: string]: string }
+    apiKeys?: { [url: string]: string };
     user?: string;
     password?: string;
     allowInsecure?: boolean;
diff --git a/test/providers.test.js b/test/providers.test.js
index 3b11912c02..6b9e3295b5 100644
--- a/test/providers.test.js
+++ b/test/providers.test.js
@@ -338,9 +338,9 @@ test('near json rpc fetch node status', async () => {
 });
 
 test('JsonRpc rotateRpcServers', async () => {
-    const SERVER_1 = "server1";
-    const SERVER_2 = "server2";
-    const SERVER_3 = "server3";
+    const SERVER_1 = 'server1';
+    const SERVER_2 = 'server2';
+    const SERVER_3 = 'server3';
     const provider = new nearApi.providers.JsonRpcProvider({ url: [SERVER_1, SERVER_2, SERVER_3] });
     expect(provider.connection.url.length).toEqual(3);
     expect(provider.connection.url[0]).toMatch(SERVER_1);