Run from a Git repository with a properly configured Rapporteur (https://github.com/envylabs/rapporteur) status endpoint as the first argument, this script will wait until the live revision matches the latest local revision

wait_for_deploy.rb

#!/usr/bin/env ruby

require 'json'
require 'shellwords'

unless ARGV.length == 1
  $stderr.puts "Usage: wait_for_deploy.rb https://example.com/status.json"
  exit 1
end

live_commit = nil
last_commit = `git rev-parse HEAD`.chomp
unless $?.success?
  $stderr.puts "Unable to fetch latest local git commit"
  exit 1
end
$stderr.puts "Latest commit: #{last_commit}"
until live_commit == last_commit do
  sleep 1 unless live_commit.nil?
  json_body = `curl -s --fail #{Shellwords.escape(ARGV[0])}`
  unless $?.success?
    $stderr.puts "Unable to fetch status JSON"
    exit 1
  end
  status = JSON.parse(json_body)
  $stderr.puts "Revision at start: #{status['revision']}" if live_commit.nil?
  live_commit = status['revision'].chomp
end
$stderr.puts "Current revision matches: #{live_commit}"
exit 0