# Lono

[![Build History][2]][1]

[1]: http://travis-ci.org/tongueroo/lono
[2]: https://secure.travis-ci.org/tongueroo/lono.png?branch=master

Lono is a Cloud Formation Template ruby generator.  Lono generates Cloud Formation templates based on ERB templates.

## Usage

<pre>
$ gem install lono
$ mkdir lono
$ cd lono
$ lono init
</pre>

This sets up a starter lono project with example templates.

<pre>
$ lono generate
</pre>

This generates the templates that have been defined in config folder of the lono project.

The one of starter lono config files looks like this:

```ruby
template "prod-api-app.json" do
  env,app,role = name.sub('.json','').split('-')
  source "app.json.erb"
  variables(
    :env => env,
    :app => app,
    :role => role,
    :ami => "ami-123",
    :instance_type => "m1.small",
    :port => "80",
    :high_threshold => "15",
    :high_periods => "4",
    :low_threshold => "5",
    :low_periods => "10",
    :max_size => "24",
    :min_size => "6",
    :down_adjustment => "-3",
    :up_adjustment => "3",
    :ssl_cert => "arn:aws:iam::12345:server-certificate/wildcard"
  )
end
```

The corresponding ERB template example file is [here](lib/starter_project/templates/app.json.erb).

## Template helper methods

There are helper methods that available in templates.

* partial - can be use to embed other files in a template.  The partial should be placed in the templates/partial folder of the project.  So:
  * partial('launch_config.json.erb') -> templates/partial/launch_config.json.erb

* user_data - can be used to include a user data script which is written in bash script form.  The user data script should be placed in the templates/user_data folder of the project.  So:
  * user_data('bootstrap.sh.erb') -> templates/user_data/bootstrap.sh.erb
  * user_data('db.sh.erb') -> templates/user_data/db.sh.erb

Here's how you would call it in the template.

```json
"UserData": {
  "Fn::Base64": {
    "Fn::Join": [
      "",
      <%= user_data('bootstrap.sh.erb') %>
    ]
  }
```

Within a user_data script you can call another helper method called ref.

* ref - can be use to reference other parameter or resource value within the cloud formation template.  An [example](lib/starter_project/templates/user_data/db.sh.erb) is in the [starter_project](lib/starter_project).

* find_in_map - can be use to call the find_in_map function within the cloud formation template.  An [example](lib/starter_project/templates/user_data/db.sh.erb) is in the [starter_project](lib/starter_project).

## Breaking up config/lono.rb

If you have a lot of templates, the config/lono.rb file can get unwieldy long.  You can break up the lono.rb file and put template defintions in the config/lono directory.  Any file in this directory will be automatically loaded. An [example](lib/starter_project/config/lono/api.rb) is in the starter project.


## Generate

You can generate the CF templates by running:

<pre>
$ lono generate
$ lono g -c # shortcut
</pre>

The lono init command also sets up guard-lono.  Guard-lono continuously generates the cloud formation templates.  Just run guard.

<pre>
$ guard
</pre>