How can I set DOCKER_HOST environment variable?

**docker** is installed and the service is active. But when I run a Maven build I get the error: [ERROR] Failed to execute goal io.fabric8:docker-maven-plugin:0.27.2:stop (stop-staled) on project egisso-db: Execution stop-staled of goal io.fabric8:docker-maven-plugin:0.27.2:stop failed: No given, no DOCKER_HOST environment variable, no read/writable '/var/run/docker.sock' or '//./pipe/docker_engine' and no external provider like Docker machine configured -> [Help 1] I've read some discussions where some people suggest values for this variable like tcp://... but I don't know where I can find its exact value. I thought that docker info would give some information, but no: sudo docker info|grep tcp Not sure whether its important, but I have to start the **service** using sudo, but I can use the docker as **client** as normal user.