Uptime Checker for HTTPS Services

uptime.rb

#!/usr/bin/env ruby

require "net/http"
require "openssl"
require "bundler/inline"

gemfile do
  source "https://rubygems.org"

  gem "colorize", "~> 0.8"
end

fail "Expected URL as first argument to script." unless ARGV[0]

class Poller
  attr_reader :target, :interval

  def initialize(target, interval: 1)
    @target   = target
    @interval = interval
    @requests = 0
    @errors   = 0
  end

  def start!
    puts "Tracking uptime for #{target}..."
    puts

    Signal.trap "INT" do
      puts
      puts "Stopping..."
      puts
      print_stats

      exit 1
    end

    loop do
      status = get_target_status
      update_stats(status)

      puts <<~OUT
        #{Time.now}
        ===============
        #{status.message}
      OUT

      sleep interval
    end
  end

  private

  def get_target_status
    Net::HTTP.start(uri.host, uri.port, use_ssl: true) do |http|
      cert = OpenSSL::X509::Certificate.new(http.peer_cert)
      request = Net::HTTP::Get.new(uri)

      response = http.request(request)

      Status.new(
        error: error_response?(response),
        message: <<~MSG
          Status: #{response.code.public_send(color_for_response(response))}
          Cert:   #{cert.issuer}
        MSG
      )
    rescue => err
      Status.new(
        error: true,
        message: <<~MSG
          #{"Error".red}:   #{err.class}
          Message: #{err}
        MSG
      )
    end
  end

  def uri
    @uri ||= URI(target)
  end

  def color_for_response(response)
    case response
    when Net::HTTPSuccess     then :green
    when Net::HTTPRedirection then :blue
    else                           :red
    end
  end

  def error_response?(response)
    case response
    when Net::HTTPClientError, Net::HTTPServerError
      true
    else
      false
    end
  end

  def update_stats(status)
    @requests += 1
    @errors   += 1 if status.error?
  end

  def print_stats
    puts <<~OUT
      Total Requests: #{@requests}
      Errors:         #{@errors.to_s.public_send(@errors.zero? ? :green : :red)}
    OUT
  end

  Status = Struct.new(:error, :message, keyword_init: true) do
    def error?
      error
    end
  end
end

Poller.new(ARGV[0]).start!