DB Health Check in Rails

Question

I am building an API to do a deep health check of my service.

Other than just doing a SomeTableWhichIsNeverEmpty.first == nil, is there a better way to check if my DB is up and available? Preferably, the solution would be sqlite3, postgres, and mysql compatible.

I'm on rails 3.

Answer 1

Take a look at https://github.com/blythedunham/health_monitor

Answer 2

11 years later, this post still sees some action so here's an update. I am now on Rails 7.

I create a dedicated table in the DB to which I can read and write to. Given that I wanted to make sure the db was writable, I didn't see any alternative. Since this is storing only timestamps, I felt the storage overhead was negligible. With an outside caller checking on regular intervals, it also gives a history of when we were available -- assuming the healthcheck service is operating normally, a gap in records would indicate a gap in availability.

class CreateDbStatusChecks < ActiveRecord::Migration[7.0]
  def change
    create_table :db_status_checks do |t|
      t.timestamps
    end
  end
end

Then I create an empty model. My status check calls create and last in order to verify write and read access. Very simple.

  def check_read
    DBStatusCheck.last
  rescue
    false
  end

  def check_write
    DBStatusCheck.create
  rescue
    false
  end

Answer 3

You might want to check out newrelic. They do a pretty awesome job of monitoring rails and db health. It'd be hard to write something to compete and I think it's free for 1 or 2 rails apps.