protected function getContainer()
    {
        if ($this->innerContainer instanceof ContainerInterface) {
            // Do nothing
        } elseif (!is_readable($this->innerContainer)) {
            throw new RuntimeException(
                sprintf(
                    "Unable to read file %s\n",
                    $this->innerContainer
                )
            );
        } else {
            // 'containerBuilder.php' file expects $installDir variable to be set by caller
            $installDir = $this->installDir;
            $this->innerContainer = require_once $this->innerContainer;
        }

        // Compile container if necessary
        if ($this->innerContainer instanceof ContainerBuilder && !$this->innerContainer->isFrozen()) {
            $this->innerContainer->compile();
        }
    }