ActiveJobK8s

WIP gem to make active job work with kubernetes jobs.

Roadmap for V1.0:

ActiveJob.perform_later create a Job in k8s that will execute the job
ActiveJob.perform_later with delay create a Job in k8s in suspended mode, a task will enable it as soon as the time is reached
Limiting the number of concurrent jobs (if there are more jobs they will be created in suspended mode)

Future:

Metrics (because everyone like metrics)
Retry options

Installation

Add this line to your application's Gemfile:

gem 'active_job_k8s'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install active_job_k8s

Usage

Adapter Configuration

Configure the KubeClient as documented here: https://github.com/ManageIQ/kubeclient and instantiate the adapter.

Example: Local with default kind cluster:

  kubeclient_config = Kubeclient::Config.read(ENV['KUBECONFIG'] || File.join(Dir.home, '/.kube/config'))

  config.active_job.queue_adapter = ActiveJob::QueueAdapters::K8sAdapter.new(
    kubeclient_context: kubeclient_config.context('kind-kind')
  )

Example: production configuration:

Rails.application.configure do

  auth_options = {
    bearer_token_file: "/var/run/secrets/kubernetes.io/serviceaccount/token"
  }
  ssl_options = {}
  if File.exist?("/var/run/secrets/kubernetes.io/serviceaccount/ca.crt")
    ssl_options[:ca_file] = "/var/run/secrets/kubernetes.io/serviceaccount/ca.crt"
  end
  api_endpoint = "https://kubernetes.default.svc"
  api_version = "v1"
  namespace = File.read("/var/run/secrets/kubernetes.io/serviceaccount/namespace")

  context = Kubeclient::Config::Context.new(
    api_endpoint,
    api_version,
    ssl_options,
    auth_options,
    namespace
  )

  default_manifest = YAML.safe_load(
          <<~MANIFEST
          apiVersion: batch/v1
          kind: Job
          metadata:
            name: scheduled-job-name
            namespace: default
          spec:
            template:
              spec:
                restartPolicy: Never
                containers:
                  - name: app-job
                    image: image_of_the_rails_application
                    imagePullPolicy: IfNotPresent
                    command:
                      - /bin/bash
                    args:
                      - '-c'
                      - bundle exec rails active_job_k8s:run_job

  MANIFEST
  )

  config.active_job.queue_adapter = ActiveJob::QueueAdapters::K8sAdapter.new(
    kubeclient_context: context,
    default_manifest: default_manifest
  )

end

Kubernetes Configuration

The adapter should be capable to query the kubernetes cluster, this is the role to create inside the namespace, it will add api capacity o jobs to the default ServiceAccount

kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: jobs-edit
  namespace: YOURN-NAMESPACE
rules:
  - apiGroups:
      - "batch"
    resources:
      - jobs
    verbs:
      - get
      - list
      - create
      - patch
---
kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: jobs-edit
  namespace: YOURN-NAMESPACE
subjects:
  - kind: ServiceAccount
    name: default
    namespace: default
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: jobs-edit

Job configuration

Inside you job you should describe the initial manifest for the KubernetesJob

Example:

class HelloWorldJob < ApplicationJob
  queue_as :default

  def perform(*args)
    Rails.logger.debug "Hello World"
  end
      
  #[Optional] if not present it will be taken from scheduler configuration
  # def manifest
  # .....
  # end 
      
end

The command will be inserted by the gem if not present.

      command: ["rails"]
      args: ["active_job_k8s:run_job"]

To the name of the Job we will append a timestamp to make it uniq

Development

Requirements: kind

After checking out the repo, run bin/setup to install the environment (cluster and dummy app).

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/[USERNAME]/active_job_k8s. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.

License

The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the ActiveJobK8s project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.

active_job_k8s

Runtime