What is Atomic App?

Atomic App is a reference implementation of the Nulecule Specification. It can be used to bootstrap container applications and to install and run them. Atomic App is designed to be run in a container context.

Examples using this tool may be found in the Nulecule examples library.

Getting Started

Atomic App itself is packaged as a container. End-users typically do not install the software from source. Instead using the atomicapp container as the FROM line in a Dockerfile and packaging your application on top. For example:

FROM projectatomic/atomicapp

MAINTAINER Your Name <you@example.com>

ADD /nulecule /Dockerfile README.md /application-entity/
ADD /artifacts /application-entity /artifacts

For more information see the extensive Atomic App getting started guide which goes over in detail on how to build your first Atomic App container.

Running your first Nulecule

Install Atomic App

Clone the github repository

git clone https://github.com/projectatomic/atomicapp
cd atomicapp

Install it:

sudo make install

Running Atomic App

This will run a helloworld example using the centos/apache container image on Kubernetes:

sudo atomicapp run projectatomic/helloapache

Same with Docker:

sudo atomicapp run projectatomic/helloapache --provider=docker

Fetching, modifying and running an Atomic App

Fetch a Nuleculized container, modify the answers file and launch it.

atomicapp fetch projectatomic/helloapache --destination helloapache
cd helloapache
cp answers.conf.sample answers.conf # Modify then copy
atomicapp run .


atomicapp {run,fetch,stop,genanswers,init} APP|PATH [--dry-run] [-a answers.conf] [-v] [--namespace foo] [--destination foo]

Pulls the application and it’s dependencies. If the last argument is an existing path, it looks for Nulecule file there instead of pulling the container.

  • --destination DST_PATH Unpack the application into given directory instead of current directory
  • APP Name of the image containing the application (f.e. vpavlin/wp-app)
  • PATH Path to a directory with installed (i.e. result of atomicapp install ...) app
  • --dry-run Performs a faux command of Atomic App to simulate a deployment scenario
  • -a answers.conf Provide an answers.conf file when deploying a container
  • --namespace foo Use a particular namespace for a specific provider (specifically, k8s and openshift)


Atomic App currently supports the following providers:

  • Kubernetes
  • OpenShift
  • Marathon
  • Docker


Interested in contributing? We have an awesome development guide to get you started!

Communication channels

Interested in Atomic App? We’d love to hear from you about your use of Atomic App and work together on improving it.

  • IRC: #nulecule on irc.freenode.net
  • Mailing List: container-tools@redhat.com
  • Weekly IRC Nulecule meeting: Monday’s @ 0930 EST / 0130 UTC
  • Weekly SCRUM Container-Tools meeting: Wednesday’s @ 0830 EST / 1230 UTC on Bluejeans