September, 18th–20th: DevOps Sprint

Since we have a strong history in web development, but also were involved in operating web applications we developed, the DevOps movement hit our nerves.

Under the brand name “Flying Circus” we are establishing a platform respecting the DevOps principles.

A large portion of our day-to-day work is dedicated to DevOps related topics. We like to collaborate by sharing ideas and work on tools we all need to make operations and development of web applications a smooth experience. A guiding question: how can we improve the operability of web applications?

A large field of sprintable topics comes to our mind:

Logging

Enable web application developers to integrate logging mechanisms into their apps easily. By using modern tools like Logstash for collecting and analyzing of the data, operators are able to find causes performance or other problems efficiently.

Live-Debugging and Monitoring

Monitoring is a must when operation software. At least for some people (including ourselves), Nagios is not the best fit for DevOps teams.

Deploying

We always wanted to have reproducable automated deployments. Coming from the Zope world, started with zc.buildout, we developed our own deployment tool batou. More recently upcoming projects, such as ansible, and tools (more or less) bound to cloud services like heroku.

Backup

After using bacula for a while, we started to work on backy, which aims to work directly on volume files of virtual machines.

and more…

Join us to work on these things and help to make DevOps better! The sprint will take place at our office, Forsterstraße 29, Halle (Saale), Germany. On September, 20th we will have a great party in the evening.

If you want to attend, please sign up on http://www.meetup.com/DevOps-Sprint/events/191582682/.

 

Accomodation

For your stay in Halle, we can recommend the following Hotels: “City Hotel am Wasserturm”, “Dorint Hotel Charlottenhof”, “Dormero Hotel Rotes Ross”. For those on budget, there is the youth hostel Halle (http://halle.djh-sachsen-anhalt.de/). Everything is in walking distance from our office.

Reproducable automated deployments on RaspberryPi with batou

For continuous integration during development, we use Jenkins to automatically run tests for all projects we maintain. Some time ago we wanted to increase visibility of the results, so we set up a Raspberry Pi driving a few meters of LPD8806-based LED strip on which we can address single LEDs to represent the status of individual or aggregated builds.

Automating deployments is a good idea…

After an SD Card failure we were painfully remembered how hard it can be to set up a service where all parts were deployed manually. Fortunately we wrote at least some minimal documentation on how to set everything up, so after a few days we were presented with many broken builds. Of course nobody cared about the build status with all LEDs being dark.😦

Let’s automate!

Today we wondered if we can use our deployment-tool batou to make reproduceable deployments to a raspberry pi, and did some tests on a vanilla raspbian image (2013-07-26 “Wheezy”).

Preparing your Raspberry Pi

Of course, you can not deploy to it without some simple preparations. First thing is, batou needs to be able to log on the target host with a public ssh key, so we copied our public key to the raspi which has the address 192.168.0.5 in this example:

local> ssh-copy-id pi@192.168.0.5
pi@192.168.0.5's password:
Type password of user pi, default: "raspberry"

(If you don’t have the ssh-copy-id, you have to manually append your ssh public key to /home/pi/.ssh/authorized_keys, which you will need to create on a plain installation)

Manually install minimal requirements

Batou does also have a few requirements which are needed to bootstrap the environment:

  • mercurial – to pull the buildout which sets up batou
  • python-virtualenv – to create a clean python environment for the buildout
  • python-dev – to compile libcrypto against

Note: We are currently working on batou 1.0 which most likely will no longer need any of these.

You can install all the requirements at once with the following command on your raspi:

pi> sudo aptitude install mercurial python-virtualenv python-dev

Prepare batou

Now you are ready to do your first batou deployment to a raspberry pi. For our experiments we created a small hello-world batou deployment, containing a test component which deploys a file /tmp/test which contains “foo” to a raspberry pi specified by an IP address.

To begin, clone the repository on your local machine:

local> hg clone https://bitbucket.org/gocept/batou-on-raspberrypi
local> cd batou-on-raspberrypi

Now, edit environments/pi.cfg and set the IP-address of your Raspi.

To create the nessecary scripts to do the deployment, run buildout to create a sandbox containing all dependencies of batou and the scripts you can use to deploy:

local> python bootstrap.py
…
local> bin/buildout

Deploy!

After some minutes, your batou deployment sandbox will be ready for use. You most likely modified environments/pi.cfg so you need to check in that change first, because batou refuses to deploy a dirty working copy.

local> hg ci -m 'change ip of my raspi'

To run the deployment, call batou-remote with the name of the environment (“pi”, which corresponds to environments/pi.cfg). Because the ssh user you use to connect with the target host differs from your local user, you have to specify it with --ssh-user.

local> bin/batou-remote pi --ssh-user=pi

Batou will now set up itself on the remote side and deploys all components specified in pi.cfg. To show it worked, check if the deployed file contains the correct content:

pi> cat /tmp/test
foo

Further readings

To learn more about batou, check http://batou.readthedocs.org.

If you want deploy your real life mission critical python applications into a fully automated environment using batou, head over to the Flying Circus.

TL;DR

  • Create reproducable automated deployments for your software is great fun.
  • Preparing a raspi to be a target host for batou 0.2.12 based deployments is easy:
    • Install python-virtualenv, mercurial and python-dev.
    • Put your ssh public key on the raspi.
  • Example deployment can be found on bitbucket.

Sprint report: Deploying Python web applications – platforms and applications

Last week I met Stephan Diehl, Michael Hierweck, Veit Schiele, and Jens Vagelpohl in Berlin for a sprint. Our chosen topic was “Python web application deployment”. In this post I’d like to recap our discussions, gocept’s perspective on those, and the deployment tool “batou” that we have been incubating in the last months.

Continue reading “Sprint report: Deploying Python web applications – platforms and applications”