Ubuntu docker compose doesn't work

Ubuntu 下 docker 运行要 sudo，然而 docker-compose 不用，所以运行 docker-compose 时会报错

ERROR: Couldn't connect to Docker daemon at http+docker://localunixsocket - is it running?

问题解决方案是统一 docker 和 docker-compose 的权限，一个方法是不用 sudo 开启 docker，步骤如下：

1. Add the docker group if it doesn't already exist: sudo groupadd docker
2. Add the connected user "$USER" to the docker group. Change the user name to match your preferred user if you do not want to use your current user: sudo gpasswd -a $USER docker
3. Either do a newgrp docker or log out/in to activate the changes to groups.

再试一下运行 docker info，发现问题就解决啦～