Cannot connect to the Docker daemon when running with sudo - macos

Question

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"

Answer 1

The following command exports a few environment variables that the subsequent docker commands use:
eval "$(docker-machine env default)"
However, if you launch docker with sudo, the exported environment variables are not accessible by the docker executable. You could potentially get it to work by passing -E flag to sudo, e.g.:
sudo -E docker pull fluxcapacitor/pipeline
But much easier option is to use docker without root like:
docker pull fluxcapacitor/pipeline

Answer 2

You have to set environment variables with:
eval "$(docker-machine env default)"
More about it here.

Answer 3

I had same probelem on my MAC, when attempted
# eval "$(docker-machine env default)"
got this error
Error checking TLS connection: Error checking and/or regenerating the certs: There was an error validating certificates for host "192.168.99.100:2376": x509: certificate is valid for 192.168.99.101, not 192.168.99.100
You can attempt to regenerate them using 'docker-machine regenerate-certs [name]'.
to regenerate certificates, find out the docker-machines available;
# docker-machine ls
Output of avalable docker machines (omitted others)
NAME ACTIVE DRIVER STATE URL SWARM DOCKER ERRORS
default - virtualbox Running tcp://192.168.99.100:2376 Unknown Unable to query docker version: Get https://192.168.99.100:2376/v1.15/version: x509: certificate is valid for 192.168.99.101, not 192.168.99.100
Generate certificates for this default docker-machine
# docker-machine regenerate-certs default
and then setup docker-machine env to default docker-machine;
# eval "$(docker-machine env default)"
and it works normally after that.

Answer 4

I have also tried the same but did not work.
later I have tried these steps on AWS CLI
$ sudo nano /etc/docker/daemon.json
{
"dns": ["8.8.8.8", "8.8.4.4"]
}
$ sudo service docker restart
$ docker pull hello-world