entrypoint.sh

#!/usr/bin/env ruby

require "json"
require "octokit"

json = File.read(ENV.fetch("GITHUB_EVENT_PATH"))
event = JSON.parse(json)

github = Octokit::Client.new(access_token: ENV["GITHUB_TOKEN"])

if !ENV["GITHUB_TOKEN"]
  puts "Missing GITHUB_TOKEN"
  exit(1)
end

if ARGV.empty?
  puts "Missing message argument."
  exit(1)
end

repo = event["repository"]["full_name"]

if ENV.fetch("GITHUB_EVENT_NAME") == "pull_request"
  pr_number = event["number"]
else
  pulls = github.pull_requests(repo, state: "open")

  push_head = event["after"]
  pr = pulls.find { |pr| pr["head"]["sha"] == push_head }

  if !pr
    puts "Couldn't find an open pull request for branch with head at #{push_head}."
    exit(1)
  end
  pr_number = pr["number"]
end
message = File.read(ARGV.join(''))

coms = github.issue_comments(repo, pr_number)
duplicate = coms.find { |c| c["user"]["login"] == "github-actions[bot]" && c["body"] == message }

if duplicate
  puts "The PR already contains a database change notification"
  exit(0)
end

github.add_comment(repo, pr_number, message)