Rhea

A web UI for managing a Kubernetes cluster

Overview

Rhea is a web UI for managing a Kubernetes cluster. It makes it very easy to:

• Create and manage replication controllers that run arbitrary commands
• Perform actions on multiple replication controllers
• Export/import the state of the cluster's replication controllers
• Monitor pods' statuses on all nodes
• Monitor the cluster's events

---

Create and manage replication controllers that run arbitrary commands:

Monitor the nodes' pods and the cluster's events:

Installation

The included Dockerfile builds a container running a Rails app with Rhea.

1. Configure Rhea by copying and modifying rhea.rb.example:
   • cp rhea.rb.example rhea.rb
   • Modify rhea.rb (see Configuration)
2. Build the container: docker build -it rhea .
3. Run it: docker run --rm -p 3000:3000 rhea

Configuration

Rhea is configured in rhea.rb. The only required configuration option is kube_api, which configures Rhea to talk to your Kubernetes API.

kube_api

These options are passed through to kubeclient, so anything that's valid in kubeclient is valid here.

No authentication

# rhea.rb
require 'rhea'

Rhea.configure do |config|
  config.kube_api = {
    url: 'https://kubernetes.example.com/api/',
    options: {}
  }
end

Client certificate authentication

Create a credentials directory in the root of this directory and copy the following files into it:

credentials/apiserver.crt
credentials/apiserver.key
credentials/ca.crt

Then configure rhea.rb to use them:

# rhea.rb
require 'rhea'

Rhea.configure do |config|
  config.kube_api = {
    url: 'https://kubernetes.example.com/api/',
    options: {
      ssl_options: {
        client_key: OpenSSL::PKey::RSA.new(Rails.root.join('config/credentials/apiserver.key').read),
        client_cert: OpenSSL::X509::Certificate.new(Rails.root.join('config/credentials/apiserver.crt').read),
        ca_file: Rails.root.join('config/credentials/ca.crt').to_s,
        verify_ssl: OpenSSL::SSL::VERIFY_PEER
      }
    }
  }
end

The credentials/* files above are generated when you create the cluster. For example, if you're using minikube, they're located in ~/.minikube/.

command_types

Command types are custom templates that let you create commands more easily. They can be used in the command creation form. $INPUT is the value that's passed in from the form input.

config.command_types = [
  {
    key: 'default',
    name: 'Default',
    format: '$INPUT'
  },
  {
    key: 'sidekiq',
    name: 'Sidekiq',
    format: 'sidekiq -q $INPUT'
  },
  {
    key: 'resque',
    name: 'Resque',
    format: 'QUEUES=$INPUT rake resque:work'
  },
  {
    key: 'goworker',
    name: 'goworker',
    format: 'worker.go -q $INPUT'
  }
]

container_options

By default, each pod has a single, minimally-configured container. You can easily configure additional container options, which will be merged into the pod's spec.template.spec.containers[0].

config.container_options = {
  'resources' => {
    'requests' => {
      'memory' => '256Mi',
      'cpu' => '250m'
    },
    'limits' => {
      'memory' => '512Mi',
      'cpu' => '1000m'
    }
  }
}

default_command_type_key

This will be used to set the default command type when creating new commands.

config.default_command_type_key = 'goworker'

default_image

This will be used to set the default image when creating new commands.

config.default_image = 'docker.registry.com/myworker:latest'

env_vars

This will be used to set custom environment variables in pods scheduled by Rhea.

config.env_vars = {
  'FOO' => 'bar'
}

Using Rhea as a Rails engine

Rhea is also available as a Rails engine. To install it in a Rails app, include it in your Gemfile:

gem 'rhea'

And mount it in routes.rb:

mount Rhea::Engine => '/rhea'

You'll then configure Rhea in config/initializers/rhea.rb. See Configuration for details.

Development

Use the sample Rails app with Rhea.

1. cd examples/rhea-rails

2. Update the rhea Gem in the sample app's Gemfile:

   • gem 'rhea', git: 'https://github.com/entelo/rhea.git' to
   • gem 'rhea', path: '../../'

3. Modify config/rhea.yml for your needs

4. bundle install

5. rails server KUBE_API_URL=http://localhost:8080/api/

6. Visit http://localhost:3000

Testing

To write tests that communicate with a Kubernetes cluster, you'll want to have a Kubernetes cluster running locally at https://vagrant:vagrant@kube.local. VCR is used to record HTTP requests and responses.

"Rhea"?

Rhea is a Greek Titan associated with ease, comfort, and fertility. In her 21st century gem form, she lets you easily and comfortably birth many Kubernetes pods.

License

Rhea is released under the MIT License. Please see the MIT-LICENSE file for details.