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

 Problem: 

Solution:  run the docker-compose with sudo

Install Docker on Ubuntu Using Default Repositories

 Step 1: Update Software Repositories

It’s a good idea to update the local database of software to make sure you’ve got access to the latest revisions.

Open a terminal window and type:

sudo apt-get update

Allow the operation to complete.

Step 2: Uninstall Old Versions of Docker

Next, it’s recommended to uninstall any old Docker software before proceeding.

Use the command:

sudo apt-get remove docker docker-engine docker.io

Step 3: Install Docker on Ubuntu 18.04

To install Docker on Ubuntu, in the terminal window enter the command:

sudo apt install docker.io

Step 4: Start and Automate Docker

The Docker service needs to be setup to run at startup. To do so, type in each command followed by enter:

sudo systemctl start docker

sudo systemctl enable docker

Step 5 (Optional): Check Docker Version

To verify the installed Docker version number, enter:

docker --version