Lono
Lono is a Cloud Formation Template ruby generator. Lono generates Cloud Formation templates based on ERB templates.
Usage
$ gem install lono
$ mkdir lono_project
$ lono init
This sets up the basic lono project with an example template in source/app.json.erb.
$ lono generate
This generates the templates that have been defined in config/lono.rb.
The example starter config/lono.rb looks like this:
ruby
template "prod-api-app.json" do
source "app.json.erb"
variables(
:env => 'prod',
:app => 'api',
:role => "app",
:ami => "ami-123",
:instance_type => "c1.xlarge",
: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
template "prod-br-app.json" do
source "app.json.erb"
variables(
:env => "prod",
:app => 'br',
:role => "app",
:ami => "ami-456",
:instance_type => "m1.medium",
:port => "80",
:high_threshold => "35",
:high_periods => "4",
:low_threshold => "20",
:low_periods => "2",
:max_size => "6",
:min_size => "3",
:down_adjustment => "-1",
:up_adjustment => "2"
)
end
The example ERB template file is in templates/app.json.erb.
User Data Helper
In the template files, there’s user_data helper method available which can be used to include a user data script. The user data script should be in 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') %>
]
]
}
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 is in the spec/project folder:
- config/lono/api.rb
Generate
You can generate the CF templates by running:
$ lono generate
The lono init command also sets up guard-lono. Guard-lono continuously generates the cloud formation templates. Just run guard.
$ guard