使用sudo运行时无法连接到Docker守护进程(Cannot connect to the Docker daemon when running with sudo)

 我的Docker服务已启动并正在运行。 但是，当试图通过使用sudo运行Docker来使用Docker时，例如： 
 
12:40:26/~ $ sudo docker pull fluxcapacitor/pipeline
Using default tag: latest
 
 我有以下错误： 
 
Warning: failed to get default registry endpoint from daemon (Cannot connect to 
the Docker daemon. Is the docker daemon running on this host?). Using system 
default: https://index.docker.io/v1/
Cannot connect to the Docker daemon. Is the docker daemon running on this host?
 
 请注意，我已经在Mac OS X上遵循了这些答案sudo docker无法连接到Docker守护进程。 码头守护程序是否在该主机上运行？ 
 
 如下： 
 
 码头机启动默认 
 
12:40:36/~ $ docker-machine start default
Starting "default"...
Machine "default" is already running.
 
 码头工人 
 
12:41:20/~ $ docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
 
 那么还有什么需要做的呢？ 
 
 这是： 
 
$ docker --version
Docker version 1.11.2, build b9f10c9
 
 在El Capitan 。 
 
 docker-machine env default输出docker-machine env default 
 
$ eval "$(docker-machine env default)"

$ docker-machine env default
export DOCKER_TLS_VERIFY="1"
export DOCKER_HOST="tcp://192.168.99.100:2376"
export DOCKER_CERT_PATH="/Users/macuser/.docker/machine/machines/default"
export DOCKER_MACHINE_NAME="default"

My Docker service is up and running. However when attempting to use Docker by running it with sudo, e.g.:
 
12:40:26/~ $ sudo docker pull fluxcapacitor/pipeline
Using default tag: latest
 
I have got the following error:
 
Warning: failed to get default registry endpoint from daemon (Cannot connect to 
the Docker daemon. Is the docker daemon running on this host?). Using system 
default: https://index.docker.io/v1/
Cannot connect to the Docker daemon. Is the docker daemon running on this host?
 
Note that I had already followed the answers on Mac OS X sudo docker Cannot connect to the Docker daemon. Is the docker daemon running on this host?
 
as follows: 
 
docker-machine start default
 
12:40:36/~ $ docker-machine start default
Starting "default"...
Machine "default" is already running.
 
docker ps
 
12:41:20/~ $ docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
 
So what more needs to be done?
 
This is:
 
$ docker --version
Docker version 1.11.2, build b9f10c9
 
on El Capitan.
 
Output of docker-machine env default
 
$ eval "$(docker-machine env default)"

$ docker-machine env default
export DOCKER_TLS_VERIFY="1"
export DOCKER_HOST="tcp://192.168.99.100:2376"
export DOCKER_CERT_PATH="/Users/macuser/.docker/machine/machines/default"
export DOCKER_MACHINE_NAME="default"

原文：https://stackoverflow.com/questions/37778439