Mercy
==========

![mercy](https://raw.githubusercontent.com/darthjee/mercy/master/mercy.jpg)

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This gem tries to make server monitoring easier and more reliable by adding an easly configurable
report and making it avaliable in a controller

Getting started
---------------
1. Add Mercy to your `Gemfile` and `bundle install`:

    ```ruby
    gem 'mercy'
    ```


2. Include in your health check controller passing the configuration to fetch your Documents
with error and render the report

  ```ruby
  class HealthCheckController < ApplicationController
    include Mercy

    status_report :failures, clazz: Document
    status_report :failures, clazz: Schedules, on: :schedules
    status_report :delays, clazz: Schedules, scope: :late, on: :schedules
    status_report :'documents.count', clazz: Document, scope: :active, type: Mercy::Range, minimum: 100
    status_report :'documents.errors', clazz: Document, scope: :'active.with_error', type: :range, maximum: 1000

    def status
      render_status
    end

    def late_status
      render_status(:schedules)
    end
  end
  ```

3. Add a route to your controller

  ```ruby
  scope path: 'health-check', controller: :health_check do
    get '/status' => :status
    get '/late-status' => :late_status
  end
  ```

3. Set the correct options on your status report to achieve a perfect report
 - clazz: Class of the object that might contain error
 - period: default search period (default: 1 day)
 - on: report bucket (default: :default)
 - type: report type (error, range or other custom report)
 
  Remembering that each report may have its onw parameters

 - ```Mercy::Error```
   - scope: scope to be fetched when trying to find objects with error (default: :with_error)
   - external_key: column to be exposed as id for the objects with error
   - threshold: default report threshold (default: 0.02)
   - base_scope: scope to be universal sample
   - uniq: when the output ids should not be repeated
   - limit: limit of ids to be outputed
 - ```Mercy::Range```
   - scope: scope of the query to be counted
   - maximum: max value accepted in the range
   - minimum: minimum value accepted in the range

4. Run the server and hit the health-check routes

 ```
 wget http://localhost:3000/health-check/status
 wget http://localhost:3000/health-check/late-status
 ```

5. Customize your request for multiple reports
 ```
 wget http://localhost:3000/health-check/status?period=3.days&threshold=0.005
 wget http://localhost:3000/health-check/late-status?period=1.hours&threshold=0.1
 ```

 6. Use the status json to understand what is wrong
 ```json
 {
   "status": "error",
   "failures": {
     "ids": [10, 14],
     "percentage": 0.5,
     "status": "error"
   },
   "delays": {
     "ids": [12],
     "percentage": 0.001,
     "status": "ok"
   }
 }
 ```