ERROR: Couldn't connect to Docker daemon at http://localhost:8443 - is it running? If it's at a non-standard location, specify the URL with the DOCKER_HOST environment variable. code example

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

open the terminal and type sudo dockerd and leave it open
open new terminal and type sudo docker-compose up -d or sudo docker-compose build