Customize Packages for Atomic Host : Ansible Automation

My earlier post automate-building-your-own-atomic-host describes how to Automate building Atomic Host with Ansible. But it is not capable of customizing packages for OSTree and build Atomic host based on it.

This post includes Ansible Automation for customizing packages of OSTree and build Atomic Host. Below are the improvements on this updated post :

  • Add packages to OSTree (It is suggested not to delete any pre-existing packages from the OSTree, that might break your Atomic host).
  • No need to create VM from the QCOW2 image will shell script anymore, It will be now all-in-one playbook.

If you do not know about Atomic host, please refer to http://www.projectatomic.io.

Requirements:

The requirements remain the same just like the earlier post. I will use Fedora distribution for the demo, but the same will be applicable for CentOS as well.

  • Make sure Ansible is installed on your system. If you are using Fedora workstation/any other platform, do not forget to install python2-dnf as well.
  • Download Atomic QCOW2 image: Fedora-Atomic.

Procedure:

Clone:

$ git clone https://github.com/trishnaguha/build-atomic-host.git
$ cd build-atomic-host/

Environment Setup:

The following will install requirements on your system, initializes OSTree and starts HTTP server as daemon service. The OSTree is made available via web server at TCP port 35000. After running the playbook you may use ip addr to check the IP Address of your HTTP server.

$ ansible-playbook setup.yml --ask-sudo-pass

Variables:

I am going to use variables applicable for Fedora. If you are using CentOS please modify the variables based on it.

  • Primary Variables.
    vars/atomic.yml
---
# Variables for Atomic host
atomicname: my-atomic                          # OSTree name
basehost: fedora-atomic/25/x86_64/docker-host  # Basehost
httpserver: 192.168.122.1                      # IP Address of HTTP Server
  • Additional packages you would like to have in your OSTree.
    vars/buildrepo.yml
# Variables for OSTree packages
repo: https://pagure.io/fedora-atomic.git
branch: f25
repodir: fedora-atomic
abs_path: /workspace                                # The absolute path to the git repo.
custommanifest: customized-atomic-docker-host.json  # The manifest that goes into the custom host(ostree) content that we are going to build.
sourcemanifest: fedora-atomic-docker-host.json      # The manifest that goes into the actual Base Fedora host(ostree) content.
packages: '"vim-enhanced", "git"'                   # Packages you want to have in your Atomic host.

Add packages like above separate by comma.

  • Variables for the VM
    vars/guests.yml
# Variables for Creating VM
domain: atomic-node                        # Domain name
image: Fedora-Atomic-25-20170228.0.x86_64  # Image name
cpu: 1
mem: 1536
os:
  variant: fedora23
path: /tmp                                 # Path to QCOW2 Image

Main Playbook:

Run the main Playbook which will create VM from QCOW2 image, compose OSTree and perform SSH-Setup and Rebase on OSTree:

$ ansible-playbook main.yml --ask-sudo-pass

Note: user-name: atomic-user, password: atomic are the credentials for the instance.
If you wish to change it, modify the cloud-init user-data.
We will have the credentials as variables/vault later.

To Check the IP Address of the VM running:

$ sudo virsh domifaddr atomic-node

Now SSH to the Atomic host and perform Reboot so that it will reboot in to custom OSTree.

$ ssh atomic-user@IP-ADDRESS-OF-VM
$ sudo systemctl reboot

SSH again and You will have your own OSTRee.

[atomic-user@atomic-node ~]$ sudo rpm-ostree status
State: idle
Deployments:
● my-atomic:fedora-atomic/25/x86_64/docker-host
       Version: 25.1 (2017-02-07 05:34:46)
        Commit: 15b70198b8ec7fd54271f9672578544ff03d1f61df8d7f0fa262ff7519438eb6
        OSName: fedora-atomic

  fedora-atomic:fedora-atomic/25/x86_64/docker-host
       Version: 25.51 (2017-01-30 20:09:59)
        Commit: f294635a1dc62d9ae52151a5fa897085cac8eaa601c52e9a4bc376e9ecee11dd
        OSName: fedora-atomic
[atomic-user@atomic-node ~]$ rpm -q git vim-enhanced
git-2.9.3-2.fc25.x86_64
vim-enhanced-8.0.386-1.fc25.x86_64

If you find any bug/idea please open up issues here. Thanks.

Atomic-Host

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Publish Docker image with Automated build

docker1

Docker is an open source tool that helps us to develop, ship and run applications.  Each and every application needs a Dockerfile. Instructions are written over Dockerfile in a layered/step-by-step structure to run the application. The Dockerfile is then built to create Docker image. We can then push the image either to Docker Hub or keep it in our Workstation. Finally to run the application we have to run container from the image which can be treated as a concept like an instance of the image since we can have more than one container of a single image. If the Docker image is not in our local Workstation we first have to pull the image from Docker hub and then run container from it. But when we need to make changes in Dockerfile(as needed to make changes in application) we have to build a new Docker image again from it. Or we can make change in the container we are running and commit it but that doesn’t reflect the Dockerfile which contains all the instructions to run an application say it for development or production purpose. Also building Docker image locally from Dockerfile makes us doing things like build, push and all manually. Automating build of Docker image from Dockerfile that is either on Github or Bitbucket is the only solution for this 🙂 .

In Short:  We first create Dockerfile and then push it to Github or Bitbucket. After authenticating Github account with Dockerhub we choose repository on Dockerhub from Github that contains the Dockerfile. After that the Dockerfile triggers build which in result creates Docker image getting ready to pull.

I will share an example of making a CentOS image having Apache httpd server pre-installed.

First we need to create a Dockerfile which can be viewed here.

FROM centos:centos6
MAINTAINER trishnag <trishnaguha17@gmail.com>
RUN yum -y update; yum clean all
RUN yum -y install httpd
RUN echo "This is our new Apache Test Site" >> /var/www/html/index.html
EXPOSE 80
RUN echo "/sbin/service httpd start" >> /root/.bashrc 

Then push the Dockerfile to Github. I have created a repository named CentOS6-Apache and pushed the Dockerfile to it. The repository can be found here.

After doing so

  • Go to DockerHub and Settings —> Linked Account —> Link your Github account.
  • Create —> Create Automated Build —> Create Auto-build Github.
  • Select the repository that contains Dockerfile of your application.
  • Create followed by the Automating build process.

After the image is built successfully you will be able to see Success in Build Details which indicates that the image is successfully built. The Image is now live on docker hub https://hub.docker.com/r/trishnag/centos6-apache.

Now we have to test the image to make sure whether Apache httpd server is actually pre-installed or not.

docker pull trishnag/centos6-apache  #Pull the image from Dockerhub
docker run -t -i -d trishnag/centos-apache /bin/bash #Run the container as daemon
docker ps #Get the name of the container

CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
8bcd1199bb8f trishnag/centos6-apache "/bin/bash" 2 minutes ago Up 2 minutes 80/tcp jovial_cray

docker logs jovial_cray #To see What is happening on bash of container.Gives httpd status
docker inspect jovial_cray | grep IPAddress #Shows the IPAddress
curl 172.17.0.1 #curl the IPAddress we got
This is our new Apache Test Site

We just have got the text that we echoed out to index.html. Hence we can finally come to conclusion that Apache httpd server has already been pre-installed in the image.

Now even if we commit changes to the Dockerfile on Github we really don’t have to worry about the image. The build process of Docker image starts automatically once any changes are committed to Dockerfile. When we pull the newly built image and run container we will be able to find those changes.

Automating build process really makes our life easier.

Resources: