Docker containers in Oh-My-Vagrant

The Oh-My-Vagrant (omv) project is an easy way to bootstrap a development environment. It is particularly useful for spinning up an arbitrary number of virtual machines in Vagrant without writing ruby code. For multi-machine container development, omv can be used to help this happen more naturally.

Oh-My-Vagrant can be very useful as a docker application development environment. I’ve made a quick (<9min) screencast demoing this topic. Please have a look:

https://download.gluster.org/pub/gluster/purpleidea/screencasts/oh-my-vagrant-docker-screencast.ogv

If you watched the screencast, you should have a good overview of what’s possible. Let’s discuss some of these features in more detail.

Pull an arbitrary list of docker images:

If you use an image that was baked with vagrant-builder, you can make sure that an arbitrary list of docker images will be pre-cached into the base image so that you don’t have to wait for the slow docker registry every time you boot up a development vm.

This is easily seen in the CentOS-7.1 image definition file seen here. Here’s an excerpt:

VERSION='centos-7.1'
POSTFIX='docker'
SIZE='40'
DOCKER='centos fedora'		# list of docker images to include

The GlusterFS community gracefully hosts a copy of this image here.

If you’d like to add images to a vm you can add a list of things to pull in the docker omv.yaml variable:

---
:domain: example.com
:network: 192.168.123.0/24
:image: centos-7.1-docker
:docker:
- ubuntu
- busybox
:count: 1
: vms: []

This key is also available in the vms array.

Automatic docker builds:

If you have a Dockerfile in a vagrant/docker/*/ folder, then it will get automatically added to the running vagrant vm, and built every time you run a vagrant up. If the machine is already running, and you’d like to rebuild it from your local working directory, you can run: vagrant rsync && vagrant provision.

Automatic docker environments:

Building and defining docker applications can be a tricky process, particularly because the techniques are still quite new to developers. With Oh-My-Vagrant, this process is simplified for container developers because you can build an enhanced omv.yaml file which defines your app for you:

---
:domain: example.com
:network: 192.168.123.0/24
:image: centos-7.0-docker
:extern:
- type: git
  system: docker
  repository: https://github.com/purpleidea/docker-simple1
  directory: simple-app1
:docker: []
:vms: []
:count: 3

By listing multiple git repos in your omv.yaml file, they will be automatically pulled down and built for you. An example of the above running would look similar to this:

$ time vup omv1
Cloning into 'simple-app1'...
remote: Counting objects: 6, done.
remote: Total 6 (delta 0), reused 0 (delta 0), pack-reused 6
Unpacking objects: 100% (6/6), done.
Checking connectivity... done.

Bringing machine 'omv1' up with 'libvirt' provider...
==> omv1: Creating image (snapshot of base box volume).
==> omv1: Creating domain with the following settings...
==> omv1:  -- Name:              omv_omv1
==> omv1:  -- Domain type:       kvm
==> omv1:  -- Cpus:              1
==> omv1:  -- Memory:            512M
==> omv1:  -- Base box:          centos-7.0-docker
==> omv1:  -- Storage pool:      default
==> omv1:  -- Image:             /var/lib/libvirt/images/omv_omv1.img
==> omv1:  -- Volume Cache:      default
==> omv1:  -- Kernel:            
==> omv1:  -- Initrd:            
==> omv1:  -- Graphics Type:     vnc
==> omv1:  -- Graphics Port:     5900
==> omv1:  -- Graphics IP:       127.0.0.1
==> omv1:  -- Graphics Password: Not defined
==> omv1:  -- Video Type:        cirrus
==> omv1:  -- Video VRAM:        9216
==> omv1:  -- Command line : 
==> omv1: Starting domain.
==> omv1: Waiting for domain to get an IP address...
==> omv1: Waiting for SSH to become available...
==> omv1: Starting domain.
==> omv1: Waiting for domain to get an IP address...
==> omv1: Waiting for SSH to become available...
==> omv1: Creating shared folders metadata...
==> omv1: Setting hostname...
==> omv1: Rsyncing folder: /home/james/code/oh-my-vagrant/vagrant/ => /vagrant
==> omv1: Configuring and enabling network interfaces...
==> omv1: Running provisioner: shell...
    omv1: Running: inline script
==> omv1: Running provisioner: docker...
    omv1: Configuring Docker to autostart containers...
==> omv1: Running provisioner: docker...
    omv1: Configuring Docker to autostart containers...
==> omv1: Building Docker images...
==> omv1: -- Path: /vagrant/docker/simple-app1
==> omv1: Sending build context to Docker daemon 54.27 kB
==> omv1: Sending build context to Docker daemon 
==> omv1: Step 0 : FROM fedora
==> omv1:  ---> 834629358fe2
==> omv1: Step 1 : MAINTAINER James Shubin <james@shubin.ca>
==> omv1:  ---> Running in 2afded16eec7
==> omv1:  ---> a7baf4784f57
==> omv1: Removing intermediate container 2afded16eec7
==> omv1: Step 2 : RUN echo Hello and welcome to the Technical Blog of James > README
==> omv1:  ---> Running in 709b9dc66e9b
==> omv1:  ---> b955154474f4
==> omv1: Removing intermediate container 709b9dc66e9b
==> omv1: Step 3 : ENTRYPOINT python -m SimpleHTTPServer
==> omv1:  ---> Running in 76840da9e963
==> omv1:  ---> b333c179dd56
==> omv1: Removing intermediate container 76840da9e963
==> omv1: Step 4 : EXPOSE 8000
==> omv1:  ---> Running in ebf83f08328e
==> omv1:  ---> f13049706668
==> omv1: Removing intermediate container ebf83f08328e
==> omv1: Successfully built f13049706668

real	1m12.221s
user	0m5.923s
sys	0m0.932s

All that happened in about a minute!

Conclusion:

I hope these tools help, if you’re following my git commits, you’ll notice that there are some new features I haven’t blogged about yet. Kubernetes integration exists, so please have a look, and hopefully I’ll have some screencasts and blog posts about this shortly.

Happy hacking,

James

Advertisements

Sharing dev environments with Oh-My-Vagrant

With Oh-My-Vagrant (omv) you can set up a dev environment in seconds. (Read the omv introduction if you’ve never used it before!) Since everything is defined in a single omv.yaml file, it is easy to share your cluster prototype with a friend! The one missing feature was associating code with this config file. This is now possible! Let me show you how it works…

In the omv.yaml file there is an extern variable. It is a list of each external repository which you’d like to include. Each element in this list is a hash of key value pairs. Currently four are supported: type, system, repository, directory.

An example will help you visualize this:

---
:domain: example.com
:network: 192.168.123.0/24
:image: fedora-21
:extern:
- type: git
  system: ansible
  repository: https://github.com/eparis/kubernetes-ansible
  directory: kubernetes
:reallyrm: true

In this example, we list one external repository. It is of type git, it is intended for use with the ansible integration provided by omv, the repository is hosted by eparis, and we’ll store this in a local directory called kubernetes.

We currently only support git repositories, but patches for other systems are welcome. A few different “systems” are supported, including puppet, docker and kubernetes. They each integrate with omv, and, as a result can pull code and modules into the appropriate places. Any repository path that is valid is acceptable (including local file paths) and lastly, the directory you choose is entirely up to you!

The most important part that I need to mention is the reallyrm variable. If this is set to true, and you remove a git repository from the list, omv will make sure that it removes it! Since some users might not expect this behaviour, it defaults to false, and shouldn’t bite you! If you’re not comfortable with it, don’t use it! I find it incredibly helpful.

Here’s a small screencast to show you some examples of this in action:

oh-my-vagrant-extern-screencast.ogv

I hope you enjoyed this. Please share and enjoy, and I’ll be back soon to explain some more of the features! Documentation patches are appreciated!

Happy hacking,

James