Ruby Kubernetes Operator

If you do not want to create your operators for kubernetes in golang, it is difficult to find good frameworks. This gem is used to implement a few basic functions andand helps eucht with a quick entry into the world of operators. Unlike the operator-sdk in golang, the gem does not offer yaml generators. You would have to create the crds.yml yourself.

Current features

• Basic: Watch changes of custom resources and trigger upsert (add, update) or delete methods.
• Cache resource version in yaml store to avoid double events.
• Handle the finalizer on create and after delete events.
• Update status after successfuly passed upsert methods.
• Provides an event handler, so you can easy create events forcustom resources. On deletion it also will clean up all lost events.

Installation

The gem is hosted on rubygems.org, so you can install it with ...

gem install kubernetes-operator

... or with bundler in your Gemfile.

source 'https://rubygems.org'
gem 'kubernetes-operator'

Usage

An full example you will found in ./example, also you can check our yard documentation.

Watch events

The simplest start is an operator who only listens to the upsert events and writes the status in a logfile.

crdGroup = "exmaple.com"
crdVersion = "v1alpha1"
crdPlural = "myres"

def my_custom_action(obj)
    puts "Do some cool stuff for #{obj["metadata"]["crd_status"]} action of #{obj["metadata"]["name"]}"
end

opi = KubernetesOperator.new(crdGroup,crdVersion,crdPlural)
opi.setUpsertMethod(method(:my_custom_action))
opi.run()

You can also add an delete methode.

...

def my_custom_action_fordelete(obj)
    puts "Delete #{obj["metadata"]["crd_status"]} action of #{obj["metadata"]["name"]}"
end

...

opi.setDeleteMethod(method(:my_custom_action_fordelete))
opi.run()

Return status subressources

If you have activated the subresource status in your crd, you can return a status [:status] object.

Example resource definition:

spec:
  ...
  subresources:
    status: {}
  ...
  validation:
    openAPIV3Schema:
      properties:
        ...
        status:
          type: object
          properties:
            message:
              type: "string"
              minimum: 1

Example upsert method:

def upsert(obj)
    {:status => {:message => "upsert works fine"}}
end

Result:

Status:
  Message:  upsert works fine

Logging

The operator framework generates an Log4r::Logger, you can also use this to send logs.

@logger = opi.getLogger()
@logger.info("create new fancy sample with the name #{obj["spec"]["sampleName"]}")

Events

You can add events to your custom resource by using the EventHelper.

@eventHelper = opi.getEventHelper()
@eventHelper.add(obj,"fancy sample event")

Result:

Events:
  Type    Reason  Age   From                Message
  ----    ------  ----  ----                -------
  Normal  Upsert  36s   KubernetesOperator  fancy sample event