Fails with "no DOCKER_HOST" error

[cwoodruf]

With:
mvn package -Pdocker

Got the following after running an unchanged clone:

[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 27.216 s
[INFO] Finished at: 2019-05-21T17:54:32-07:00
[INFO] Final Memory: 27M/198M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal io.fabric8:docker-maven-plugin:0.20.1:build (docker:build) on project helloworld: Execution docker:build of goal io.fabric8:docker-maven-plugin:0.20.1:build 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]

On ubuntu 16 using docker 18.0.9:
$ sudo docker version
Client:
Version: 18.09.6
API version: 1.39
Go version: go1.10.8
Git commit: 481bc77
Built: Sat May 4 02:35:27 2019
OS/Arch: linux/amd64
Experimental: false

Server: Docker Engine - Community
Engine:
Version: 18.09.6
API version: 1.39 (minimum version 1.12)
Go version: go1.10.8
Git commit: 481bc77
Built: Sat May 4 01:59:36 2019
OS/Arch: linux/amd64
Experimental: false

[cwoodruf]

Running with sudo fixes the issue:

sudo mvn package -Pdocker

Perhaps the documentation should be clearer? I think this is only an issue on linux.