Rails health check

01_README.md

HealthCheck

Install

Add the following line to your Gemfile

gem "server_health_check-rails"

Usage

Copy health_check.rb in config/initializers/health_check.rb

HEALTHCHECK_SECRET_KEY env var allow you to add a token in url.

You could update or create new checks. The example do the following checks:

• active_record: Check ActiveRecord
• redis: Check redis connection
• sidekiq: Check sidekiq redis respond to PING
• cache: Check Rails.cache write and read
• database: Check database respond
• migrations: Check migrations are up to date
• activestorage: Check ActiveStorage upload and download works
• external_services: Here you can check external status (ex: check status page of shopify)
• email: Check email configuration (smtp only)

Response

{
  "status": {
    "heartbeat": "OK",
    "active_record": "OK",
    "redis": "OK",
    "sidekiq": "OK",
    "cache": "OK",
    "database": "OK",
    "migrations": "OK",
    "activestorage": "OK",
    "external_services": "OK",
    "email": "OK"
  }
}

health_check.rb

# frozen_string_literal: true

module HealthCheck
  CACHE_TIMEOUT = 10.seconds
  SMTP_TIMEOUT = 30.0.seconds

  class << self
    def heartbeat
      true
    end

    def check_database
      ActiveRecord::Migrator.current_version if defined?(ActiveRecord)
    end

    def check_migrations
      ActiveRecord::Migration.check_pending!.nil?
    end

    def check_cache
      unless Rails.cache.write("__health_check_cache_test__", "ok", expires_in: CACHE_TIMEOUT)
        raise "Unable to write to cache."
      end
      
      raise "Unable to read to cache." unless Rails.cache.read("__health_check_cache_test__") == "ok"

      true
    end

    def check_activestorage
      service = ActiveStorage::Blob.service
      service.upload(".healthcheck", StringIO.new("ok"))

      service.download(".healthcheck") == "ok"
    end

    def check_email
      case ActionMailer::Base.delivery_method
      when :smtp
        check_smtp(ActionMailer::Base.smtp_settings)
      else
        false
      end
    end

    def check_smtp(settings)
      status = ""

      smtp_client.start(settings[:domain], settings[:user_name], settings[:password], settings[:authentication]) do
        status = smtp.helo(settings[:domain]).status
      end

      raise "SMTP: #{status || "unexpected error"}." unless status.match?(/^250/)

      true
    end

    def check_external_services
      # test external services like Shopify.
      #
      # response = Net::HTTP.get_response(URI("https://status.shopify.com/index.json"))
      # (JSON.parse(response.body)&.dig("status", "indicator")) == "none"
    end

    def check_sidekiq
      raise "Wrong configuration. Missing 'sidekiq' gem" unless defined?(::Sidekiq)

      ::Sidekiq.redis do |r|
        raise "Sidekiq.redis.ping returned #{res.inspect} instead of PONG" unless r.ping == "PONG"
      end

      true
    end

    private

    def smtp_client(settings)
      smtp = Net::SMTP.new(settings[:address], settings[:port])
      smtp.enable_starttls_auto if settings[:enable_starttls_auto]
      smtp.open_timeout = SMTP_TIMEOUT
      smtp.read_timeout = SMTP_TIMEOUT
      smtp
    end
  end
end

secret_key = "-#{ENV["HEALTHCHECK_SECRET_KEY"]}" if ENV.key?("HEALTHCHECK_SECRET_KEY")
ServerHealthCheckRails::Config.path = +"/health_check#{secret_key}"

ServerHealthCheckRails::Config.logger = Rails.logger

ServerHealthCheckRails.check("heartbeat") { HealthCheck.heartbeat }
ServerHealthCheckRails.check_active_record!
ServerHealthCheckRails.check_redis!
ServerHealthCheckRails.check("sidekiq") { HealthCheck.check_sidekiq }
ServerHealthCheckRails.check("cache") { HealthCheck.check_cache }
ServerHealthCheckRails.check("database") { HealthCheck.check_database }
ServerHealthCheckRails.check("migrations") { HealthCheck.check_migrations }
ServerHealthCheckRails.check("activestorage") { HealthCheck.check_activestorage }
# ServerHealthCheckRails.check("external_services") { HealthCheck.check_external_services }
ServerHealthCheckRails.check("email") { HealthCheck.check_email }