Helpers

You can extend Lono’s DSL with helpers. This is a powerful way to keep your code organized and readable.

Example Helper

You define helpers in the blueprint’s app/helpers folder as a module. The module name should be the camelized version of the file name. Here’s an example:

app/helpers/ec2_helper.rb:

module Ec2Helper
  def ec2_instance(logical_id, props={})
    default = {
      instance_type: "t3.micro",
      image_id: ref("AmiId"),
    }
    props.reverse_merge!(default)

    resource("Instance", "AWS::EC2::Instance", props)
  end

  def security_group(logical_id, props={})
    resource("SecurityGroup", "AWS::EC2::SecurityGroup", props)
  end
end

You can use the helper in your templates:

app/templates/demo.rb:

ec2_instance("Instance",
  security_group_ids: [get_att("SecurityGroup.GroupId")]
)
security_group("SecurityGroup",
  group_description: "demo security group",
)

These are helpers you can define. Lono also comes with some builtin Lono helpers

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