Cannot connect to the Docker daemon on macOS

On a supported Mac, run:

brew install --cask docker

Then launch the Docker app. Click next. It will ask for privileged access. Confirm. A whale icon should appear in the top bar. Click it and wait for "Docker is running" to appear.

You should be able to run docker commands now:

docker ps

Because docker is a system-level package, you cannot install it using brew install, and must use --cask instead.

Note: This solution only works for Macs whose CPUs support virtualization, which may not include old Macs.

On macOS the docker binary is only a client and you cannot use it to run the docker daemon, because Docker daemon uses Linux-specific kernel features, therefore you can’t run Docker natively in OS X. So you have to install docker-machine in order to create VM and attach to it.

Install docker-machine on macOS

If you don't have docker-machine command yet, install it by using one of the following methods:

• Using Brew command: brew install docker-machine docker.

• Manually from Releases page:

  $ curl -L https://github.com/docker/machine/releases/download/v0.16.1/docker-machine-`uname -s`-`uname -m` >/usr/local/bin/docker-machine
  $ chmod +x /usr/local/bin/docker-machine
  

See: Get started with Docker for Mac.

Install Virtualbox

docker-machine relies on VirtualBox being installed and will fail if this isn't the case. If you already have VirtualBox, you can skip this step.

• Using Homebrew: brew cask install virtualbox
• Manually using the releases on Virtualbox.org

You will need to actively accept loading the Virtualbox kernel extension in the OS X Security panel and then proceed to restart the machine for the next commands not to fail with Error: VBoxNetAdpCtl: Error while adding new interface

Configure docker-machine on macOS

Create a default machine (if you don't have one, see: docker-machine ls):

docker-machine create --driver virtualbox default

Then set-up the environment for the Docker client:

eval "$(docker-machine env default)"

Then double-check by listing containers:

docker ps

See: Get started with Docker Machine and a local VM.

Related:

• Brew install docker does not include docker engine?
• For Linux, see: Docker can't connect to docker daemon
• For Windows, see: Docker warning: failed to get default registry endpoint from daemon

I had this same issue I solved it in the following steps:

docker-machine restart

Quit terminal (or iTerm2, etc, etc) and restart

eval $(docker-machine env default)

I also answered it here

I have Mac OS and I open Launchpad and select docker application. from reset tab click on restart.