Wellness

A rack middleware library that adds a health check to your service. It comes with pre made services and has the option and flexibility for you to make your own.

Usage - Rails

There are some pre configured services that are provided with this gem. However, you must require them when you need them. This is because they have external dependencies that need to be loaded, that your application may not necessarily have.

# Within the configuration block

system = Wellness::System.new('my-uber-duber-app')
system.use(Wellness::Services::PostgresService, 'database', {
  host:     ENV['POSTGRESQL_HOST'],
  port:     ENV['POSTGRESQL_PORT'],
  database: ENV['POSTGRESQL_DATABASE'],
  user:     ENV['POSTGRESQL_USERNAME'],
  password: ENV['POSTGRESQL_PASSWORD']
})
system.use(Wellness::Services::RedisService, 'redis', {
  host: ENV['REDIS_HOST']
})

config.middleware.insert_before('::ActiveRecord::QueryCache', 'Wellness::Middleware', system)

Usage - Sinatra

require 'wellness'

system = Wellness::System.new('my-uber-duber-app')
system.use(Wellness::Services::PostgresService, 'database', {
  host:     ENV['POSTGRESQL_HOST'],
  port:     ENV['POSTGRESQL_PORT'],
  database: ENV['POSTGRESQL_DATABASE'],
  user:     ENV['POSTGRESQL_USERNAME'],
  password: ENV['POSTGRESQL_PASSWORD']
})
system.use(Wellness::Services::RedisService, 'redis', {
  host: ENV['REDIS_HOST']
})

use(Wellness::Middleware, system)

Example Response

{
  "status":"UNHEALTHY",
  "details":{

  },
  "dependencies":{
    "database":{
      "status":"UNHEALTHY",
      "details":{
        "error":"no response from ping"
      }
    },
    "sidekiq":{
      "status":"HEALTHY",
      "details":{
        "processed":0,
        "failed":0,
        "busy":0,
        "enqueued":0,
        "scheduled":0,
        "retries":0,
        "default_latency":0,
        "redis":{
          "uptime_in_days":"0",
          "connected_clients":"1",
          "used_memory_human":"979.22K",
          "used_memory_peak_human":"1.02M"
        }
      }
    }
  }
}

Custom Services

Creating custom services is really easy. Always extend Wellness::Services::Base.

Once that is done, you must implement the #check method.

The parameters passed into the service at creation are stored under #params. Under no circumstances, should you ever modify the original parameters list at run time. It can lead to unintended consequences, and weird bugs.

# Your custom service
class MyCustomService < Wellness::Services::Base
  def check
    if params[:foo]
      {
        'status': 'HEALTHY'
      }
    else
      {
        'status': 'UNHEALTHY'
      }
    end
  end
end

# Initialize the wellness system
system = Wellness::System.new('my-app')
system.use(MyCustomService, 'some service', {foo: 'bar'})

# Load it into your rack
use(Wellness::Middleware, system)

Custom Details

# Your custom detail component
class MyDetail < Wellness::Detail
  def check
    {
      'foo' => 12,
      'bar' => 31,
      'qux' => options[:qux]
    }
  end
end

# Initialize the wellness system
system = Wellness::System.new('my-app')
system.use(MyDetail, 'something', { qux: 9000 })

# Load it into your rack
use(Wellness::Middleware, system)

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request