Cannot create cache directory /home/ubuntu/.composer/cache/repo/https---packagist.org/

Cannot create cache directory /home/ubuntu/.composer/cache/repo/https---packagist.org/, or directory is not writable. Proceeding without cache
Cannot create cache directory /home/ubuntu/.composer/cache/files/, or directory is not writable. Proceeding without cache

在ubutun上部署Laravel项目的时候，碰到以上问题。目前未找到解决办法，只是执行的时候稍慢，无缓存运行。如果有找到比较好的办法，请留言。