Resque::Kubernetes::Probes

This gem injects code into Resque and Resque::Scheduler that touches a file in the tmp directory resque_health for Resque and resque_scheduler_health for Resque::Scheduler. These files can then be used by the Kubernetes liveness probes to check that the worker and scheduler is running properly.

Installation

Add this line to your application's Gemfile:

gem 'resque-kubernetes-probes'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install resque-kubernetes-probes

Usage

Download the script in your Dockerfile

The script is simple and checks that the heartbeat file has been updated in the last interval seconds.

RUN curl -f -o /usr/local/bin/resque_health_check -L "https://raw.githubusercontent.com/apoex/resque-kubernetes-probes/master/bin/resque_health_check" && \
      chmod +x /usr/local/bin/resque_health_check

Resque

The gem hooks into resque's heartbeat logic and by default the heartbeat interval is quite high (60 seconds). We recommend lowering the default value and making it configurable through environment variables.

Resque.heartbeat_interval = ENV.fetch("RESQUE_HEARTBEAT_INTERVAL", 10).to_i
Resque.prune_interval = Resque.heartbeat_interval * 5

livenessProbe:
  timeoutSeconds: 1
  periodSeconds: 5
  exec:
    command:
      - resque_health_check
      - tmp/resque_health

Resque Scheduler

The gem does not inject itself into resque-scheduler by default, to do that you need to add the probe to the list of required files.

gem "resque-kubernetes-probes", require: ["resque/kubernetes/probes/resque", "resque/kubernetes/probes/resque-scheduler"]

livenessProbe:
  timeoutSeconds: 1
  periodSeconds: 5
  exec:
    command:
      - resque_health_check
      - tmp/resque_scheduler_health

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/micke/resque-kubernetes-probes.

License

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