Fix hostname to work on MacOS (#2)

A quick fix to mostly return 'localhost' as the host name of a container

This is largely based on the Ruby version's handling with the DOCKER_HOST stuff stripped out

src/GenericContainer.php

@@ -72,9 +72,20 @@ public function withEnv(array $env): self
 
     public function getHost(): string
     {
+        // @todo implement env vars like DOCKER_HOST
+
+        if (!$this->insideContainer()) {
+           return 'localhost';
+        }
+
         return $this->inspect()->gateway;
     }
 
+    private function insideContainer(): bool
+    {
+        return file_exists("/.dockerenv");
+    }
+
     public function getMappedPort(string $port): int
     {
         return $this->inspect()->ports[$port];

src/Module/MySql/MySqlContainer.php

@@ -27,6 +27,15 @@ public function __construct(
             ]);
     }
 
+    public function getHost() : string
+    {
+        $host = parent::getHost();
+
+        // depending on compile flags, mysql tries to connect on a local socket when
+        // given 'localhost' as host so we need to correct it
+        return $host == 'localhost' ? '127.0.0.1' : $host;
+    }
+
     public function getDsn(): string
     {
         return "mysql:host={$this->getHost()};port={$this->getFirstMappedPort()};dbname={$this->database}";