dockhand 0.1.0

Multi docker image build management

layout	title
default	Shipwright | The right way to build, tag and ship shared Docker containers.

Shipwright builds shared Docker images within a git repository in the right order and publishes them tagged with git’s revision/branch information so you’ll never loose track of an image’s origin.

It’s the perfect tool for building and publishing your images to places like Docker Hub or your own private registry. Have a look at our motivation to see why we built it and the pain points it solves for you.

Installation

Shipwright is a simple python script you can install with pip

$ pip install shipwright

Quickstart

Once installed, simply change to a project of yours that contains multiple Dockerfiles and is in git.

Add a json formatted file named .shipwright.json to the root directory of your project. At minimum it should contain the version number of your Shipwright config and a namespace which is either your docker hub user name or the URL to your private repository.

1.0 is the current version for the config.

{
  "version": 1.0,
  "namespace": "[your docker hub name or private repository]"
}

Additionally your config file can map directory names to alternative docker repositories. For example here is a .shipwright.json for the docker hub user shipwright that also maps the root of the git repository to the docker image shipwright/shared and the /foo directory to shipwright/awesome_sauce.

{
  "version": 1.0,

  "namespace": "shipwright",
  "names": {
    "/": "shipwright/shared",
    "/foo": "shipwright/awesome_sauce"
}

Now you can build all the docker images in the git repo by simply changing to any directory under your git repo and running:

$ shipwright

This will recurse through all the directories, looking for ones that contain a Dockerfile. Shipwright will build these Dockerfiles in order and by default tag them with <namespace>/<dirname>:<git commit> along with <namespace>/<dirname>:<git branch> and <namespace>/<dirname>:latest

Working example

We have a sample shipwright project you can use if you want to try this out right away.

$ git clone https://github.com/6si/shipwright-sample.git
$ cd shipwright-sample
$ shipwright

NOTE: you can use any username you’d like while building locally. In the above example we use ``shipwright``. Nothing is published unless you use the ``push`` command. For your own projects, substitute ``shipwright`` in the above example with your (or your organizations) official docker hub username or private repository.

Notice that if you run the shipwright a second time it will return immediately without doing anything. Shipwright is smart enough to know nothing has changed.

Shipwright really shines when you switch git branches.

$ git checkout new_feature
$ shipwright

Notice that shipwright only rebuilt the shared library and service1, ignoring the other projects because they have a common git ancestry. Running docker images however shows that all the images in the git repository have been tagged with the latest git revision, branch and latest.

In fact, as Shipwright builds containers it rewrites the Dockerfiles so that they require the base images with tags from the current git revision. This ensures that the entire build is deterministic and reproducible.

Building

By default, if you run shipwright with no arguments, it will build all Dockerfiles in your git repo. You can specify one or more specifiers to select fewer images to build. For example you can build a single images and its dependencies by simply specifying its name on the command line.

$ shipwright <namespace>/some_image

Run `shipwright –help’ for more examples of specifiers and their uses.

Publishing

With one command Shipwright can build your images and push them to a remote repository.

$ shipwright push

If you like you can just push your latest images without building.

$ shipwright push --no-build

The same specifiers for building also work with push. You might use this to build an entire tree in one step then push a specific image like so.

$ shipwright build
$ shipwright push -e <namespace>/public_image

Purging

After using Shipwright for a bit, images tend to build up that you no longer use. Shipwright has a experimental command purge that will remove all stale images. A stale image is an image that is not the latest of at least one branch. Images tagged with branch names that are no longer in git will also be removed.

$ shipwright purge