Multi-Container Application Packaging With Nulecule

I got an opportunity to talk about “Project Atomic and Multi-container application packaging”  in recent docker meetup Bangalore. I have posted my slides to slideshare [1].

However I thought of giving more context and further pointers to the presentation through this blog.

As mentioned in my slide, Nulecule is a specification to define a multi-container applications.  So that we can get rid of the custom shell scripts, long docker run commands, moving the required configuration files and instructions about how to deploy the application to the end user.

Checkout the YouTube video about why we need  Nulecule: From the Nulecule Nest to an Atomic App

However just having a specification will not solve the problem. We need a code to do the required work to run multi-container application using Nulecule specification and that is Atomic App project .

Atomic App performs all actions to run the application by reading the Nulecule spec. Atomic App is used as a docker image.

To run the Atomic App installer for your application , atomic command line is used.

Here is the workflow if you want to build Atomic App installer for your application using Nulecule specification.   Please keep in mind that when I say application, I am actually talking about multi-container application.


Write Nulecule specification files. Which also  includes manifesto files for underlying required orchestration platform (e.g. Kubernetes, OpenShift, Docker Compose, Apache Mosos Marathon etc)

Here is a blog from Ratnadeep about how he created a nulecule-ized application ->


Create the layered docker image (use Atomic App docker image as base image) of the application. Which will include Nulecule specification and Atomic App code.

You can push the new image to your local docker registry or public docker hub for your use.


Running the Atomic App image for the application. Here is a example of running a helloapache Atomic App ->

Note that there are three way to run an Atomic App i.e.

  • Option 1: Non-interactive defaults
  • Option 2: Unattended
  • Option 3: Install and Run

Here is a YouTube video which shows a demo : WordPress Nulecule Demo

For further read check  Vasik’s presentation or Nulecule github project.

Get Involved:

Nulecule Poject:
Atomic App:

Check the README files of the above projects for relevent communication channels for participating in the project.


Using Imagefactory to build Vagrant images

Fedora Koji buildsystem and CentOS Community build system i.e. cbs  uses  imagefactory at the back-end of Koji to build Vagrant images.  I have used it as through cbs/koji but wanted to give it a try as I am looking for  easier methods to build adb-atomic-developer-bundle . Specially for developers who don’t have access to Fedora or CentOS build system.

Imagefactory needs a kvm/libvirt hypervisor to build images and it converts them for other providers e.g. Virtualbox or VMware Fusion


I have used my laptop (which runs Fedora 23) for this. As I have plan to hack imagefactory and I did not want to damage my laptop’s kvm setup.  So I have used nested virtualization for this. Which means I have a CentOS 7 VM which can run virtual machines.

All below steps are done on a CentOS 7 VM which has a kvm setup in place.


Imagefactory is available in Fedora and EPEL repo. But I wanted to try/test the latest code, so I generated RPMs from latest code and then installed the RPMs.

$yum install  rpmdevtools epel-release
$git clone
$cd imagefactory
$make rpm
$cd imagefactory_plugins
$make rpm
$cd ~/rpmbuild/RPMS/noarch/
$sudo yum localinstall ./*

Building Vagrant Images:

For building Vagrant box I have used Ian’s example git repo. He is the maintainer and one of the primary developer for imagefactory.

Below commands are copied from imagefactory-examples git repo.

$ git clone
$ cd imagefactory-examples/vagrant/

Once you are in the “imagefactory-examples/vagrant/” directory, you can see the required files are already there for running commands to generate image for Fedora 22. So we can start running required commands.

For getting a working Vagrant box we need to run three commands (as mentioned below) to create appropriate OVA image. Each command will give a UUID for the intermediate image file name and we need to use the UUID in the next command.

$ sudo imagefactory --debug base_image \
  --file-parameter install_script ./f22-vagrant.ks \
  --parameter offline_icicle true \
============ Final Image Details ============
UUID: 109cb45f-bbd2-4a27-ba5f-42e2d368be32
Image build completed SUCCESSFULLY!
$ sudo imagefactory --debug target_image --id 109cb45f-bbd2-4a27-ba5f-42e2d368be32  rhevm

============ Final Image Details ============
UUID: ce0dce5f-a1d1-4c1a-8e9b-fc56e022a1bc
Image build completed SUCCESSFULLY!
$ sudo imagefactory --debug target_image --parameter rhevm_ova_format vagrant-libvirt --id ce0dce5f-a1d1-4c1a-8e9b-fc56e022a1bc ova

============ Final Image Details ============
UUID: 36fcb589-06b8-447b-85bf-ed4715bd2a93
Type: target_image
Image filename: /var/lib/imagefactory/storage/36fcb589-06b8-447b-85bf-ed4715bd2a93.body
Image build completed SUCCESSFULLY!

The last step will generate the F22 image for libvirt provider. You can rename it as (usually Vagrant images have .box extension) and start using it.

$ cp /var/lib/imagefactory/storage/36fcb589-06b8-447b-85bf-ed4715bd2a93.body ./


Linux Container Track at FUDCon, Pune 2015

FUDCon is the Fedora Users and Developers Conference, a major free software event. It is an annual event per region (e.g. APAC). This year FUDCon APAC is  happening at Pune, India From 26th June to 28th June 2015.  For details check out the FUDCon India home page.

FUDCon is always free to attend for anyone in the world. If you are looking for open source and free software contributors/developers, learn latest/new technologies, learn how to contribute to Fedora and other upstream projects, want to hangout and hack on interesting stuff , it is one of the finest place to be present.

This year we are having a Linux container track in FUDCon for full day. The idea of a separate track came because of the more number of talks/workshops proposals submitted related to containers and high interest from community about learning Linux containers e.g. Docker related technologies.

To start with, we have a talk about “Running Project Atomic and Docker on Fedora” in the main track by me and Aditya on Saturday, 27th June 2015. And the container track is on next day i.e. Sunday 28th June 2015.

Here are the list of talks and workshops planned for the container track.

Note : The topics of the container track has changed from the time I had published the blog.  So the I have updated the above list.

For the workshops, you need to carry your laptop. We are planning provide preconfigured virtual machine images for KVM and Virtual box. Also planning to distribute the images using use usb sticks/thumb drives. So if you have usb/thumb drive, please carry them with you as it will help you/others to quickly set-up their environments.

So if you are interested to learn about Linux containers or hack around Linux containers, Docker, come join us on container track in FUDCon 2015, Pune.