rename eth0 to generic

sysinfo caters to more than IP...

src/sysinfo/eth0.js

@@ -1,21 +0,0 @@
-'use strict';
-
-exports = module.exports = {
-    getIp: getIp
-};
-
-var assert = require('assert'),
-    os = require('os'),
-    SysInfoError = require('../sysinfo.js').SysInfoError;
-
-function getIp(callback) {
-    assert.strictEqual(typeof callback, 'function');
-
-    try {
-        var ip = os.networkInterfaces().eth0[0].address;
-        return callback(null, ip);
-    } catch (e) {
-        return callback(new SysInfoError(SysInfoError.INTERNAL_ERROR, e));
-    }
-}
-

src/sysinfo/generic.js

@@ -0,0 +1,30 @@
+'use strict';
+
+exports = module.exports = {
+    getIp: getIp
+};
+
+var assert = require('assert'),
+    os = require('os'),
+    SysInfoError = require('../sysinfo.js').SysInfoError;
+
+function getIp(callback) {
+    assert.strictEqual(typeof callback, 'function');
+
+    try {
+        var interfaces = os.networkInterfaces();
+        // https://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames/
+        for (var ifname in interfaces) {
+            if (!ifname.match(/^(en|eth)/)) continue;
+
+            for (var obj of interfaces[ifname]) { // array
+                if (obj.family === 'IPv4') return callback(null, obj.address);
+            }
+        }
+
+        return callback(new SysInfoError(SysInfoError.INTERNAL_ERROR, new Error('Could not find interface')));
+    } catch (e) {
+        return callback(new SysInfoError(SysInfoError.INTERNAL_ERROR, e));
+    }
+}
+