ansible-playbook + buildah = a beatiful container image
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TomasTomecek fix tests
Signed-off-by: Tomas Tomecek <ttomecek@redhat.com>
Latest commit 590ccc0 Oct 16, 2018

README.md

ansible-bender

This is a tool which bends containers using Ansible playbooks and turns them into images. It has a pluggable builder selection — it is up to you to pick the tool which will be used to construct your container image. Right now the only supported builder is buildah. More to come in future. ansible-bender (ab) relies on Ansible connection plugins for performing builds.

tl;dr Ansible is the frontend, buildah is the backend.

I described this concept a while ago in this blog post.

You may be asking: why not ansible-container? This tool is actually heavily inspired by ansible-container: the main distinction is that ansible-container covers the complete lifecycle of a containerized application while ab takes care of image builds only.

Please note that this project is not affiliated with the Ansible project. It's just using Ansible to do something magical.

Status: proof of concept

Features:

  • You can build your container images with buildah as a backend.
  • Ansible playbook is your build recipe.
  • You are able to set various image metadata via CLI:
    • working directory
    • environment variables
    • labels
    • user
    • default command
    • exposed ports
  • You can do volume mounts during build.
  • Caching mechanism:
    • Every task result is cached as a container image layer.
    • You can turn this off with --no-cache

Installation

ansible-bender will be on PyPI starting from version 0.2.0.

In the meantime, please install it from github directly:

$ pip3 install --user git+https://github.com/TomasTomecek/ab@0.1.0

Oh right, and ab is tested only with python 3.

Usage

Please note that buildah requires root privileges so you need to invoke ab as root.

You may noticed that I refer to ansible-bender as ab. That was the initial name and also the name of the CLI tool, so I decided to stick to it.

Right now, ab has just a single command and that is... build:

$ ab build -e SOME=VALUE -l some=other-value -- ./tests/functional/data/basic_playbook.yaml docker.io/library/python:3-alpine this-is-my-image

PLAY [all] ***********************************************************************************************************************************

TASK [Gathering Facts] ***********************************************************************************************************************
ok: [this-is-my-image-cont]

TASK [Run a sample command] ******************************************************************************************************************
changed: [this-is-my-image-cont]

TASK [create a file] *************************************************************************************************************************
changed: [this-is-my-image-cont]

PLAY RECAP ***********************************************************************************************************************************
this-is-my-image-cont      : ok=3    changed=2    unreachable=0    failed=0

Getting image source signatures
Skipping fetch of repeat blob sha256:73046094a9b835e443af1a9d736fcfc11a994107500e474d0abf399499ed280c
Skipping fetch of repeat blob sha256:8b63854c53f36e35be6b38f35ba6c0cb9ccffdf43ca67fcf74ff7a8011a126c4
Skipping fetch of repeat blob sha256:83b96d0bacdae9d29f02d93fb861aa612d0a50a3e6ff838d8ef1ac18d6588a47
Skipping fetch of repeat blob sha256:95d81b13128eaecbeb8526d03456d6bcba587220a3c23bf8c0d35b542667cb8d
Skipping fetch of repeat blob sha256:98801e48f5965cc825524f30acad1485f797241999f66a2234d12cf9a6967f8a
Copying blob sha256:eb20406495adfe66c0e2b6d89a37d4fe2f5fcf3bedf064588ce7b4b87ff33746

 0 B / 434.50 KiB [------------------------------------------------------------]
 434.50 KiB / 434.50 KiB [==================================================] 0s
Copying config sha256:7558393975c749748a292835a4708c583d574a282f9d79be7e6e6cc8b38be8f0

 0 B / 5.11 KiB [--------------------------------------------------------------]
 5.11 KiB / 5.11 KiB [======================================================] 0s
Writing manifest to image destination
Storing signatures
7558393975c749748a292835a4708c583d574a282f9d79be7e6e6cc8b38be8f0
Image 'this-is-my-image' was built successfully \o/

The command line is a bit longer. That's because all metadata about our target image is in there:

$ ab build                                       \  # this is the command
     -e SOME=VALUE                               \  # -e sets environment variables
     -l some=other-value                         \  # -l sets labels
     --                                          \  # two dashes separate options from arguments
     ./tests/functional/data/basic_playbook.yaml \  # first argument is a path to a playbook
     docker.io/library/python:3-alpine           \  # second one is a base image (and is pulled if it's not present)
     this-is-my-image                            \  # and finally, target image name

Here is a proof that the image is in there:

$ podman images this-is-my-image
REPOSITORY                   TAG      IMAGE ID       CREATED        SIZE
localhost/this-is-my-image   latest   7558393975c7   1 minute ago   84.4MB

TODO past 0.1.0

  • Configurable layering
  • A caching mechanism
  • Configurable caching
  • A fancy name!
  • You can build images with podman (needs Ansible connection plugin for podman)
  • You can build images with docker (incubator maybe?)