An Ansible Tutorial | Hacker News Reader

An Ansible Tutorial

serversforhackers.com

54 pointsfideloper14 comments

I love Ansible.

What's scary about shell scripts is the lack of idempotence (if you accidentally run them twice, things break).

What's annoying about chef/puppet is the bootstrapping overhead -- you can't start from a blank slate system, because you still need to install puppet-client or ruby+dependencies. So now you're paying to store a bunch of semi-pre-configured images with some out-of-date ruby gems or an old puppet-client. If you want to start from a blank image, then you're using shell scripts to install the toolchain that will let you avoid using shell scripts (or worse - doing it by hand!).

Ansible is idempotent ssh + shell scripting, so it solves the 'blank slate' problem nicely. It only requires python, which is bundled by default on ubuntu servers.

That was well worded! I tried to say that in the article but didn't manage it as succinctly :D

Personally I love how it makes it easy to convert existing shell scripts. One of my projects is Vaprobash - vagrant provisioning bash scripts - which contains mostly non-idempotent scripts. (It uses bash scripts purposefully as a teaching tool). Making an ansible version of it will be nice as well.

I'm not sure what bootstrapping overhead you're talking about. You can do a knife bootstrap to bootstrap nodes, not sure about puppet.

I didn't say it was difficult, I said it was annoying. The bootstrapping step isn't just easier when using Ansible, it doesn't exist.

Come one, it's not that hard to do a yum install puppet or use cobbler for provisioning and install puppet along with the OS.

It certainly isn't. You can just do:

    ansible webservers -m yum -a "name=puppet state=latest" -s

Or just use ansible for provisioning and install puppet along with the OS. Or something...

The idempotence issue of shell scripts addressed (with Go): https://github.com/visionmedia/stack/

Also, there's Rex now (in Perl), which, in my opinion, is better than Ansible as I hate writing code in YAML - I'd rather do it in Perl if Python/Go/Rust are not a option.

Stack looks cool, but I can't use it to repair a broken configuration. A commit log recording which commands have already run doesn't verify that the system is in the correct state.

This weeks edition of Servers for Hackers goes from using ad-hoc commands (shell and other modules), to Playbooks and finally abstracting everything out to a Role with templates, files and variables.

I clicked on this thinking it would be something involving the ansibles from the Ender's Game series which allow instant communication across large stretches of space. I should probably take my lunch soon.

That would be awesome, but sadly I haven't figured out beating the speed of light for intra-galactic communication.

Forget intr-galactic communication, we need c+ to talk to the bleedin' cluster.

that word predates card's usage; i think it was le guin. ..but yes, i do the same thing every time there's a heading that mentions it.

Yeah it is a key plot device in quite a few of Ursula Le Guin books. Pretty sure Card even gives credit in the appendix of one of his books.

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