Adding sync external assets feature.

backend/.gitignore

@@ -1,7 +1,9 @@
 # See http://help.github.com/ignore-files/ for more about ignoring files.
 
-# production config
-mempool-config.json
+# production config and external assets
+*.json
+!mempool-config.sample.json
+
 icons.json
 
 # compiled output

backend/mempool-config.sample.json

@@ -13,7 +13,8 @@
     "INITIAL_BLOCKS_AMOUNT": 8,
     "MEMPOOL_BLOCKS_AMOUNT": 8,
     "PRICE_FEED_UPDATE_INTERVAL": 3600,
-    "USE_SECOND_NODE_FOR_MINFEE": false
+    "USE_SECOND_NODE_FOR_MINFEE": false,
+    "EXTERNAL_ASSETS": []
   },
   "CORE_RPC": {
     "HOST": "127.0.0.1",

backend/src/api/liquid/icons.ts

@@ -6,10 +6,10 @@ class Icons {
   private static FILE_NAME = './icons.json';
   private iconIds: string[] = [];
   private icons: { [assetId: string]: string; } = {};
-  constructor() {
-    if (config.MEMPOOL.NETWORK !== 'liquid') {
-      return;
-    }
+
+  constructor() {}
+
+  public loadIcons() {
     if (!fs.existsSync(Icons.FILE_NAME)) {
       logger.warn(`${Icons.FILE_NAME} does not exist. No Liquid icons loaded.`);
       return;

backend/src/config.ts

@@ -16,6 +16,7 @@ interface IConfig {
     MEMPOOL_BLOCKS_AMOUNT: number;
     PRICE_FEED_UPDATE_INTERVAL: number;
     USE_SECOND_NODE_FOR_MINFEE: boolean;
+    EXTERNAL_ASSETS: string[];
   };
   ESPLORA: {
     REST_API_URL: string;
@@ -78,6 +79,7 @@ const defaults: IConfig = {
     'MEMPOOL_BLOCKS_AMOUNT': 8,
     'PRICE_FEED_UPDATE_INTERVAL': 3600,
     'USE_SECOND_NODE_FOR_MINFEE': false,
+    'EXTERNAL_ASSETS': [],
   },
   'ESPLORA': {
     'REST_API_URL': 'http://127.0.0.1:3000',

backend/src/index.ts

@@ -21,6 +21,8 @@ import backendInfo from './api/backend-info';
 import loadingIndicators from './api/loading-indicators';
 import mempool from './api/mempool';
 import elementsParser from './api/liquid/elements-parser';
+import syncAssets from './sync-assets';
+import icons from './api/liquid/icons';
 
 class Server {
   private wss: WebSocket.Server | undefined;
@@ -77,6 +79,7 @@ class Server {
 
     this.setUpWebsocketHandling();
 
+    await syncAssets.syncAssets();
     diskCache.loadMempoolCache();
 
     if (config.DATABASE.ENABLED) {
@@ -87,6 +90,10 @@ class Server {
       statistics.startStatistics();
     }
 
+    if (config.MEMPOOL.NETWORK === 'liquid') {
+      icons.loadIcons();
+    }
+
     fiatConversion.startService();
 
     this.setUpHttpApiRoutes();

backend/src/sync-assets.ts

@@ -0,0 +1,32 @@
+import axios from 'axios';
+import * as fs from 'fs';
+const fsPromises = fs.promises;
+import config from './config';
+import logger from './logger';
+
+const PATH = './';
+
+class SyncAssets {
+  constructor() { }
+
+  public async syncAssets() {
+    for (const url of config.MEMPOOL.EXTERNAL_ASSETS) {
+      await this.downloadFile(url);
+    }
+  }
+
+  private async downloadFile(url: string) {
+    const fileName = url.split('/').slice(-1)[0];
+    logger.info(`Downloading external asset: ${fileName}...`);
+    try {
+      const response = await axios.get(url, {
+        responseType: 'stream', timeout: 30000
+      });
+      await fsPromises.writeFile(PATH + fileName, response.data);
+    } catch (e: any) {
+      throw new Error(`Failed to download external asset. ` + e);
+    }
+  }
+}
+
+export default new SyncAssets();