I never remember what some of these HttpServletRequest
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I have a cluster and a group variable (in test/staging/prod) holding the hostname of the cluster master. For each host, I want to derive a variable which is set to either "slave" or "master" and use it in templates.

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A post about development practices, speed, and frustration.

My wife has mentioned that she likes my passion for doing things right in software development. That made me thinking, why do I actually care so much and do not just enjoy the coding itself? It boils down to that I am not happy until my code is in production. Seeking the satisfaction of having my code used by and helping people while trying to eliminate all unnecessary mental drain is behind all the practices that I embrace and evangelize. It's a drug I like to take often, in small doses.

practices = f(max(delivered value), min(mental energy))

So how does this relate to DevOps, Continuous Delivery, testing, single-piece-flow, Lean Startup, Clojure? It is simple.


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As a citizen of a country that has been invaded by Hilter in 1938 under the pretext of protecting local Germans and again invaded by Russia in 1968, I cannot watch another such invasion and annexation taking place in Europe while EU does little of any consequences.
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Ansible 1.5 has partial support for recursive copy of files:

• the synchronize module, using rsync
  • cons: does not support group=, owner=
  • -C and --diff - it does not print diff of the files changed; when running ansible with -v, it will print output of rsync's --itemize-changes, i.e., for each changed file/dir, something like "<f.st...... conf/httpd.conf\n" (< = file uploaded, s = size changed, t = timestamp changed, . = this attribute has not been changed)
• the copy module
  • -C --diff - it only reports "changed" without naming the changed files or showing diffs (unless there is only one changed file)
• the local_action module, used to run rsync manually (essentially the same as synchronize but more control)
• So the only way to do a kind of recursive copy with working diff is to use copy with with_fileglob for each directory and subdirectory :-(

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Few tips for troubleshooting Ansible, based on my brief experiences with Ansible 1.4 (read: do not rely on this info too much).

Run ansible-playbook in the verbose mode

ansible-playbook -vvvv ... will provide you with plenty of details of what is going on. (Notice that additional v:s, starting from none, add more detail.)

Use ./hacking/test-module

Check out Ansible sources and use the ./hacking/test-module script - see Developing Modules.


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Recommended Readings

Development
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It is tricky to manage JBoss with a provisioner such as Puppet or Ansible because its domain.xml contains not only rather static configuration but also sections that change quite often such as deployments. So how can we manage the static parts of domain.xml with f.ex. Ansible while still enabling developers to deploy at will via jboss-cli (and thus changing the <deployments> sections of the file)? Here is one possible solution, based on extracting the sections from the current file and merging them into the template.


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1. Problem

Let me start with a story. Once upon time
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The most important lesson I have learned in 2013 is that I won't change anything by writing critical blog posts and talking to like-minded people. Fostering the "we vs. them," we who are right vs. them idiots sentiment is ineffective, even destructive. To be able to achieve anything, I have to talk to the people with opposite opinions and understand them. They are rarely ***holes and typically have good reasons for their opinions. Only by understanding those reasons and the background, history, and emotions they stem from - and hopefully helping the "opponents" understand some of my reasons and context - we can find a common ground and common goals that we can build upon to go further - perhaps not in harmony but still together rather than against each other.

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If you ever need to persuade management why it might be better to deploy a larger change in multiple stages and push it to customers gradually, read on.

A deployment of many changes is risky. We want therefore to deploy them in a way which minimizes the risk of harm to our customers and our companies. The deployment can be done either in an all-at-once (also known as big-bang) way or a gradual way. We will argue here for the more gradual ("stepwise") approach.

Big-bang or stepwise deployment?

A big-bang deployment seems to be the natural thing to do: the full solution is developed and tested and then replaces the current system at once. However, it has two crucial flaws.


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I have created a small project to demonstrate some features of Ansible, the new DevOps hotness, including Vagrant VMs for running Ansible and for testing the configuration. Either go straight to

https://github.com/holyjak/ansible-example-with-vm

or continue reading the copy & paste here.

This project has three things of interest:

1. A non-trivial Ansible configuration that demonstrates couple of useful features and tricks
2. A Vagrant/VirtualBox virtual machine with Ansible & co. to make it easy to run it (even on Windows)
3. Another VM that can be used to test the configuration

And of course all the plumbing that makes them work together. It might be therefore a good base for Ansible projects of your own.


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Since JBoss EAP 6.1 / AS 7.2.0 is modular and you can exclude what modules are visible to your webapp, you would expect it to be easy to ignore the built-in implementation of JAX-RS (Rest Easy 2.3.6) and use a custom one (3.0.6). However, sadly, this is not the case. You are stuck with what the official guide suggests, i.e. upgrading Rest Easy globally - provided that no other webapp running on the server becomes broken by the upgrade.


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(Cross-posted from blog.iterate.no.)

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Recommended Readings

• ThoughtWorks latest interactive Technology Radar 1/2014(fixed link to pdf for Jan 2014:)
• The other kind of software debt - competency debt

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