Docker-in-Docker Drone plugin

This is a plugin for Drone 1.0 that is aimed mainly at enabling Testcontainers to be used during CI build/test steps. Due to Drone's architecture, Docker-in-Docker is often the most practical way to run builds that require a Docker daemon.

This plugin:

• Is based upon an Docker-in-Docker image
• Includes a startup script that:
  • Starts a nested docker daemon
  • Optionally starts a pull of required images (in parallel with your build, so as to reduce overall time spent waiting for images to be pulled)
  • Starts a specified build container inside the Docker-in-Docker context, containing your source code and with a docker socket available to it
  • Stores/restores image layers within the CI workspace, for best efforts caching. Even when cached, images will still be pulled to enforce up-to-date checks.

Prerequisites

• (Drone 1.0): To enable on a per-repository basis, enable the Trusted setting for the repository. Or

Usage/Migration (Drone 1.0)

Modify the build step of the pipeline to resemble:

kind: pipeline
name: default

steps:
  ...
  - name: build
    privileged: true
    image: jopecko/dind-drone-plugin
    settings:
      image: openjdk:8-jdk-alpine
      command:
      - java -version
      # Not mandatory, but enables pre-fetching of images in parallel with the build, so may save time:
      prefetch_images:
      - "redis:4.0.6"

When migrating to use this plugin from an ordinary build step, note that:

• Note that commas are not supported within commands items due to the way these are passed in between Drone and this plugin.
• prefetch_images is optional, but recommended. This specifies a list of images that should be pulled in parallel with your build process, thus saving some time.
• mounts is an optional list of volumes you can have the dind container mount on your underlying container when its started. Note that they must first be listed in the volumes section of this plugin before they can be mounted.

Copyright

This repository contains code which was mainly developed at Skyscanner, and is licenced under the Apache 2.0 Licence.

(c) 2017-2019 Skyscanner Ltd.