Fix determination of IP address from within container

src/Handler.php

@@ -210,7 +210,9 @@ class Handler extends BaseHandler {
         'projectname' => $projectname,
         'ci_home' => '/home/gitlab-runner',
         'docker0' => [
-          'ip' => $this->getLocalIpv4('docker0'),
+          'ip' => ($this->isCiContext() || $this->isLocalDevMode()) ?
+            $this->getDockerGateway() :
+            $this->getLocalIpv4('docker0'),
         ],
         'live' => [
           'root' => '',
@@ -334,37 +336,50 @@ class Handler extends BaseHandler {
     return $local_addrs[$interface] ?? '127.0.0.1';
   }
 
+  /**
+   * @return string
+   */
+  private function getDockerGateway(): string {
+    $container = $this->readContainerConfig();
+    return $container['NetworkSettings']['Gateway'];
+  }
+
   /**
    * @param $projectRoot
    *
    * @return string
    */
   private function getDockerMountSource($projectRoot): string {
+    $currentDir = getcwd();
+    $container = $this->readContainerConfig();
+    foreach ($container['Mounts'] as $mount) {
+      if (empty($projectRoot)) {
+        if ($currentDir === $mount['Destination']) {
+          return $mount['Source'];
+        }
+      }
+      else {
+        if (strpos($projectRoot, $mount['Destination']) === 0) {
+          return $mount['Source'] . substr($projectRoot, strlen($mount['Destination']));
+        }
+      }
+    }
+    return getcwd();
+  }
+
+  private function readContainerConfig() {
     try {
-      $currentDir = getcwd();
       $output = [];
       exec('basename "$(cat /proc/1/cpuset)"', $output);
       $id = reset($output);
       $output = [];
       exec('docker container inspect ' . $id, $output);
-      $container = json_decode(implode('', $output), TRUE)[0];
-      foreach ($container['Mounts'] as $mount) {
-        if (empty($projectRoot)) {
-          if ($currentDir === $mount['Destination']) {
-            return $mount['Source'];
-          }
-        }
-        else {
-          if (strpos($projectRoot, $mount['Destination']) === 0) {
-            return $mount['Source'] . substr($projectRoot, strlen($mount['Destination']));
-          }
-        }
-      }
+      return json_decode(implode('', $output), TRUE)[0];
     }
     catch (\Exception $ex) {
       // Ignore.
     }
-    return getcwd();
+    return [];
   }
 
 }