galea/dependencies-plugin repository overview

⁠Drone Dependencies Layer Plugin

Plugin for the DroneCI solution⁠ in order to pull or build a dependency layer image.

This plugin can be used to add a pipeline or step layer for building a dependency layer image for a project.

⁠Context

This plugin is to respond to the need of wanting faster drone builds by multi-layering the environment build of a project.

As well as accelerating builds, this ensures that the environments themselves with all necessary dependencies are saved to easily revert back if ever there is an issue.

⁠Example usage

Given a Python code project with all dependencies being stored inside a requirements.txt file, a dependency layer could be as the following deps.Dockerfile:

FROM python:3.6.8-slim-stretch

RUN mkdir -p /app

COPY requirements.txt /app/.

RUN pip install -U pip setuptools wheel

ENV PIP_WHEEL_DIR=/wheelhouse \
    WHEELHOUSE=/wheelhouse \
    PIP_FIND_LINKS=/wheelhouse

WORKDIR /app

RUN pip wheel numpy \
    && while read p; do pip wheel $p; done < requirements.txt

This image would be used within the projects main Dockerfile image as so:

FROM myrepo/mypythonimage-deps:latest

WORKDIR /app

RUN while read p; do pip install --no-index -f /wheelhouse $p; done < requirements.txt \
  && rm -rf /wheelhouse
 
# Rest of Dockerfile commands
[...]

This way, the environment is downloaded and built only if the requirements.txt file is changed. This is maintained by collecting the md5 hashsum of the requirement files and using them as the image tag. The plugin checks if the image tag hashsum already exists, if so, it simply pulls the image for future usage during the drone build, otherwise, the plugin builds the image with the hashsum image tag and any tag given as a parameter (latest in our example) so that the main Dockerfile can pull the image without needing to calculate the hash itself.

Multiple dependency files can be used to constitute the hashsum tag. Given the following example with a NodeJS project using package.json and package-lock.json:

FROM node:10.15.0

RUN mkdir -p /app

WORKDIR /app

COPY package-lock.json /app/.
COPY package.json /app/.

RUN npm ci

The main project image could be the following:

FROM myrepo/mynodeimage-deps:latest

COPY . /app/.

EXPOSE 80

ENTRYPOINT ["npm", "run"]
CMD ["start"]

The below pipeline configuration demonstrates simple usage of the plugin:

steps:
- name: pull_or_build_deps
  image: galea/dependencies-plugin
  settings:
    image: galea/mypython-image-deps
    files: [ requirements.txt ]
    tag: latest
    dockerfile: ./deps.Dockerfile
  volumes: # Necessary to retain the image over all pipelines
  - name: docker_socket
    path: /var/run/docker.sock

⁠Parameter Reference

• image: Image repository for the dependency layer image to be stored
• files: Array of files to be used for the checksum image tag
• tag Single "master" tag to be used for the dependency image layer
• dockerfile Path and name to the Dockerfile used to build the dependency layer
• registry: Registry to be used for pull/push of the image. Defaults to public docker hub.
• username: Username for the registry
• password: Password for the registry (used with username)