add replication configuration file parser

lib/Config.js

@@ -280,6 +280,9 @@ class Config extends EventEmitter {
         if (process.env.S3_LOCATION_FILE !== undefined) {
             this.locationConfigPath = process.env.S3_LOCATION_FILE;
         }
+        if (process.env.S3_REPLICATION_FILE !== undefined) {
+            this.replicationConfigPath = process.env.S3_REPLICATION_FILE;
+        }
 
         // Read config automatically
         this._getLocationConfig();
@@ -351,6 +354,17 @@ class Config extends EventEmitter {
         } catch (err) {
             throw new Error(`could not parse config file: ${err.message}`);
         }
+        if (this.replicationConfigPath) {
+            try {
+                const repData = fs.readFileSync(this.replicationConfigPath,
+                  { encoding: 'utf-8' });
+                const replicationEndpoints = JSON.parse(repData);
+                config.replicationEndpoints.push(...replicationEndpoints);
+            } catch (err) {
+                throw new Error(
+                    `could not parse replication file: ${err.message}`);
+            }
+        }
 
         this.port = 8000;
         if (config.port !== undefined) {