General syntax

General information about Ruby and its syntax can be found at https://www.ruby-lang.org/en/documentation/. Although it is not necessary it's highly recommended to have a basic knowledge of Ruby.

Naming policy

To conform with the Ruby naming policies most identifiers that come from Kubernetes, such as resource kinds and resource properties, are translated into the underscore notation. The following table shows the correspondence between Sunstone and Kubernetes identifiers:

Kubernetes identifier	Sunstone identifier
ConfigMap	config_map
DaemonSet	daemon_set
hostIPC	host_ipc
automountServiceAccountName	automount_service_account_name

Setting resource properties values

Every modifiable property (not marked as Readonly) accepts two forms of changing value - assignment and command. Assigning value is easy and straightforward:

R.deployment(:frontend).replicas = 2

Command version is not much harder by more aesthetic:

R.deployment :frontend do
  replicas 2
end 

Boolean properties

In addition to the getter (object.property) and setter (object.property = <value>) methods Boolean properties define two more: question mark and exclamation sign methods.

Question mark method (object.property?) returns true if property value is other than nil or false. Exclamation sign method (object.property!) sets property value to true.

Arrays

Array properties are read-only - you can not assign new array to those properties - but you can modify content of that arrays using helper methods or push or << methods. For example, to specify container command you can either use command helper of << method:

R.deployment :frontend do
  init_container 'check-backend' do
    image 'busybox'
    image_pull_policy :IfNotPresent
    
    command 'sh', '-c', 'ping -c 1 backend'
  end
end

R.deployment :frontend do
  init_container 'check-backend' do
    image 'busybox', :IfNotPresent

    command << 'sh'
    command << '-c'
    command << 'ping -c 1 backend'
  end
end

The latter one is a little bit ugly, but still can be used in some situations.