werehamster / heru Goto Github PK

Heru, in its heart, is a DSL to describe the state of a UNIX system. You specify which files, user accounts, groups etc. should exist. If the system does not match the desired state, heru takes actions to correct that.

In that regard it's very similar to puppet. In fact, much of heru was directly inspired by puppet. However, there are significant differences. The most important is that heru aims to be standalone. The goal is to not have any external dependencies. Just drop it into a folder and you're ready to go. Also, heru does not provide you with any infrastructure. You are expected to use whatever tools you are already using to distribute the configuration files. These two things together make heru very small, lightweight and hopefully easier to configure.

First you have to describe your hosts (nodes). Each node has its own file, and contains the network configuration and manifests which should be applied to it. A manifest is a collection of one or more resources which should be present.

Let's take a closer look. A node description might look something like this:

exports.manifests = [
  'sshd', 'mysql'
]

The sshd manifest might describe that the file /etc/ssh/sshd_config needs to exist, have certain permissions and contents:

{ Manifest, Action } = require 'heru'
class module.exports extends Manifest

  'path:/etc/ssh/sshd_config': ->
    type: 'file', mode: 0644, user: 'root', group: 'root', action: ->
      Action.Render 'sshd_config'

If the file does not exist, heru will create it. The Render action takes the sshd_config template file and writes it to its correct location. There are other actions which you can use, and there are also cases where you don't have to specify an action.

If the syntax seems familiar to you, it's maybe because heru and all its configuration files are written in Coffee-Script.

I recommend that you install heru into your /root/.heru folder, with the following structure:

runtime/  - The heru runtime (clone this repo here)
library/  - Library with your manifests
nodes/    - Node descriptions

Then you need to install Node.js and Coffee-Script. Node.js is fairly easy to compile (./configure --without-ssl && make). You can clone Coffee-Script into a directory and then add its bin/ folder to your path. In due time there will be a fully automated install script.

This project has its home on GitHub. You can create tickets, fork the project and send me pull requests.