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

通过docker-compose 的build up 等命令时报如下错误

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

If it's at a non-standard location, specify the URL with the DOCKER_HOST environment variable.

导致该问题出现的原因有多种，下面为问题对应的解决办法

1. 当前用户不在docker用户组
   需要把用户添加到用户组，命令如:
   sudo gpasswd -a ${USER} docker
docker-compose up
   注意: 添加到docker用户组后要重新登录shell再up。

2. docker服务器未启动, 启动命令如下：
   sudo systemctl start docker // 或者 sudo service docker start
docker-compose up

3. docker服务启动，被缓存影响，可通过重启解决
   sudo systemctl restart docker // 或者 sudo service docker restart
docker-compose up

4. 也许使用sudo 就好了
   sudo docker-compose up

5. docker-compose版本太老了,更新版本

   sudo curl -L "https://github.com/docker/compose/releases/download/1.23.1/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
   sudo chmod +x /usr/local/bin/docker-compose
   docker-compose up
   

6. 重启系统

   sudo reboot
   docker-compose up