create a Continuos Delivery pipeline with Google Container Engine (GKE), Docker, Travis and GitHub. In easy words: how you can use Travis for testing and deploying applications as a Docker containers on Google Container Engine.
practice in which isolated changes in the code are consecutively tested.The aim of CI is to provide rapid feedback so that if a defect is introduced into the code base, it can be identified and corrected as soon as possible. Continuous integration tools can be used to automate the testing and the building phases: Travis, CircleCI, etc.
system for running your Docker containers, powered by Kubernetes (K8S). GKE is a managed service in Google Cloud Platform (GCP). GCP also offers a fully managed Docker private registry, called Google Container Registry (GCR), which makes easy to store and access your private Docker images.
-> Travis tests the new code -> If tests pass, you open a pull request for merging to master ->Travis tests the merged code -> If tests pass, a docker image is built, pushed to GCR and deployed in the K8S cluster.