DOCKERHUB_SETUP.md

DockerHub Automated Build Setup

This document describes how to set up automated DockerHub container builds to build, tag, and push a Docker container with the contents of the binary mirror populated by the Gitlab pipeline.

DockerHub provides information on autobuilds here.

In order to set up the automated builds, you just need to link your DockerHub repository to your source code repository on GitHub then configure some build rules telling DockerHub what source code repo actions should trigger builds and how the resulting images should be tagged. These steps are described in more detail below.

Link your DockerHub repo to your GitHub repo

Navigate to your repository on DockerHub and login. Then click on the Builds tab and choose "Link to GitHub".

Now you have a chance to choose your organization and repository.

In our case, we disable auto testing and repository links, but you may want those turned on for your automated builds. You can more more about auto tests here. Repository links allow you to trigger builds when your base image changes, but only for non-official images.

Configure builds

Configuring some autobuilds is a matter of adding a build rule for each kind of event you want to trigger a build, and in our case, setting up some environment variables you want to be available to the build process as --build-arg cli args.

In the screenshot above, you can see we have set up two build rules. The first will trigger a build whenever we push to the master branch on our linked GitHub repository. The resulting Docker image will simply be tagged latest. We have configured anoher build to be triggered upon certain tags. Any tag that starts with rev- will be noticed and autobuilt. Anything in the tag string after the rev-, will be captured and used as the image tag. For example if you wish your resulting container to be tagged sc19, you would tag the repo rev-sc19.

Note also in the screenshot above we have specified the location of the Dockerfile and build context, as well as some environment variables. You can see how the environment variables are used by looking at the docker/hooks/build file in this repo, where we issue a docker build ... command to make use of them.