Let's install Docker, to run repeatable tests in reproducible environments.
Do this on the Runner Server, which, for expediency in this tutorial, is the same as the GitLab Server, UAT and Prod. For production, you should have dedicated Runner Servers and a dedicated GitLab Server.
Install and test Docker:
curl -sSL https://get.docker.com/ | sudo sh
sudo docker run alpine /bin/echo 'Hello world'Example successful test:
ubuntu@1ddb8d03-6597-48bd-a001-9c4f5a99dd6d:~$ sudo docker run alpine /bin/echo 'Hello world'
Unable to find image 'alpine:latest' locally
latest: Pulling from library/alpine
88286f41530e: Pull complete
Digest: sha256:f006ecbb824d87947d0b51ab8488634bf69fe4094959d935c0c103f4820a417d
Status: Downloaded newer image for alpine:latest
Hello world
ubuntu@1ddb8d03-6597-48bd-a001-9c4f5a99dd6d:~$