Automate backup-utils releases

Script to automate backup-util releases using the existing conventions
and format.

The intention is to release with a single command:

```
./script/release 2.9.1
```

script/release

@@ -0,0 +1,301 @@
+#!/usr/bin/env ruby
+#/ Usage: release [--dry-run] <version>
+#/
+#/ Publish a backup-utils release:
+#/ * Updates the package changelog
+#/ * Bumps the backup-utils version if required
+#/ * Creates the release pull request
+#/ * Creates the release draft
+#/ * Tags the release
+#/ * Builds the release assets and uploads them
+#/
+#/ Notes:
+#/ * Needs GH_RELEASE_TOKEN available in the environment.
+#/ * Export GH_OWNER, GH_AUTHOR and GH_REPO if you want to tweak the build
+#/   changelog or use a different  owner/repo
+#/ * Only pull requests labeled with bug or feature will show up in the
+#/   release page and the changelog.
+#/
+# TODO: Auto-merge the release PR
+# TODO: Tag the release
+# TODO: Build and upload the binaries to the release draft
+require 'json'
+require 'net/http'
+require 'time'
+require 'erb'
+
+API_HOST = ENV["GH_HOST"] || "api.github.com"
+API_PORT = 443
+GH_REPO = ENV["GH_REPO"] || "backup-utils"
+GH_OWNER = ENV["GH_OWNER"] || "github"
+GH_AUTHOR = ENV["GH_AUTHOR"] || "Sergio Rubio <[email protected]>"
+DEB_PKG_NAME = "github-backup-utils"
+
+CHANGELOG_TMPL = """
+<%G= package_name %> (<%= package_version %>) UNRELEASED; urgency=medium
+
+<%- changes.each do |ch| -%>
+  * <%= ch.strip.chomp %>
+<% end -%>
+
+ -- <%= author %> <%= Time.now.utc.strftime('%a, %d %b %Y %H:%M:%S %z') %>
+
+"""
+
+# Override Kernel.warn
+def warn(msg)
+  unless $no_warn
+    Kernel.warn msg
+  end
+end
+
+def client
+  @http ||= begin
+    c = Net::HTTP.new(API_HOST, API_PORT)
+    c.use_ssl = true
+    c
+  end
+end
+
+def release_token
+  token = ENV["GH_RELEASE_TOKEN"]
+  raise "GH_RELEASE_TOKEN not set" if token.nil?
+
+  token
+end
+
+def get(path)
+  req = Net::HTTP::Get.new(path)
+  req['Authorization'] = "token #{release_token}"
+  client.request(req)
+end
+
+def post(path, body)
+  req = Net::HTTP::Post.new(path)
+  req['Authorization'] = "token #{release_token}"
+  req.body = body
+  client.request(req)
+end
+
+#
+# tag "v0.0.1", "foo tag",
+#     "e1d0d72078f7fbef653e705bfb0fe018bd9c772e",
+#     "foolano", "test",
+#     "Foolano Garcia", "[email protected]"
+def tag(name, message, sha, owner, repo, tagger_name, tagger_email)
+  r = {
+    "tag": name,
+    "message": "#{message}\n",
+    "object": sha,
+    "type": "commit",
+    "tagger": {
+      "name": tagger_name,
+      "email": tagger_email,
+      "date": Time.now.utc.iso8601.to_s
+    }
+  }.to_json
+  res = post("/repos/#{owner}/#{repo}/git/tags", r)
+
+  raise "Creating tag object failed (#{res.code})" unless res.kind_of? Net::HTTPSuccess
+
+  body = {
+    "ref": "refs/heads/#{name}",
+    "sha": sha
+  }.to_json
+  res = post("/repos/#{owner}/#{repo}/git/refs", body)
+
+  raise "Creating tag ref failed (#{res.code})" unless res.kind_of? Net::HTTPSuccess
+end
+
+def bug_or_feature?(issue_hash)
+  return true if issue_hash["labels"].find { |l| ["bug", "feature"].include?(l["name"]) }
+  false
+end
+
+def issue_from(owner, repo, issue)
+  res = get("/repos/#{owner}/#{repo}/issues/#{issue}")
+  raise "Issue ##{issue} not found in #{owner}/#{repo}" unless res.kind_of? Net::HTTPSuccess
+
+  JSON.parse(res.body)
+end
+
+def beautify_changes(changes, owner, repo)
+  c = []
+  changes.each do |ch|
+    if ch =~ /#(\d+)/
+      begin
+        j = issue_from(owner, repo, $1)
+        if bug_or_feature?(j)
+          c << "#{j['title']} ##{$1}"
+        end
+      rescue => e
+        warn "Warning: #{e.message}"
+      end
+    end
+  end
+
+  c
+end
+
+def changelog()
+  changes = `git log --pretty=oneline origin/stable...origin/master | grep "Merge pull request"`.lines
+  raise "Building the changelog failed" if $? != 0
+
+  changes
+end
+
+def build_changelog(changes, package_name, package_version, author, owner, repo)
+  ERB.new(CHANGELOG_TMPL, nil, "-").result(binding)
+end
+
+def update_changelog(changes, name, version, author, owner, repo, path = "debian/changelog")
+  raise "debian/changelog not found" unless File.exist?(path)
+  File.open("#{path}.new", 'w') do |f|
+    f.puts build_changelog changes, name, version, author, owner, repo
+    f.puts(File.read(path))
+  end
+  File.rename("#{path}.new", path)
+end
+
+def create_release(tag_name, branch, owner, repo, rel_name, rel_body, draft = true)
+  body = {
+    "tag_name": tag_name,
+    "target_commitish": branch,
+    "name": rel_name,
+    "body": rel_body,
+    "draft": draft,
+    "prerelease": false
+  }.to_json
+  res = post("/repos/#{owner}/#{repo}/releases", body)
+end
+
+def list_releases(owner, repo)
+  res = get("/repos/#{owner}/#{repo}/releases")
+  raise "Error retrieving releases" unless res.kind_of? Net::HTTPSuccess
+
+  JSON.parse(res.body)
+end
+
+def release_available?(owner, repo, tag_name)
+   releases = list_releases owner, repo
+   return true if releases.find { |r| r["tag_name"] == tag_name }
+
+   false
+end
+
+def bump_version(new_version, path = "share/github-backup-utils/version")
+  current_version = Gem::Version.new(File.read(path).strip.chomp)
+  if Gem::Version.new(new_version) < current_version
+    raise "New version should be newer than #{current_version}"
+  end
+  File.open("#{path}.new", 'w') do |f|
+    f.puts new_version
+  end
+  File.rename("#{path}.new", path)
+end
+
+def push_release_branch(version, changes)
+  if !system("git checkout --quiet -b release-#{version}")
+    raise "Creating release branch failed"
+  end
+
+  if !system("git commit --quiet -m 'Bump version: #{version}\n#{changes}' debian/changelog share/github-backup-utils/version")
+    raise "Error commiting changelog and version"
+  end
+
+  if !system("git push --quiet origin release-#{version}")
+    raise "Failed pushing the release branch"
+  end
+end
+
+def create_release_pr(version, owner, repo, release_body)
+  body = {
+    "title": "Bump version: #{version}",
+    "body": release_body,
+    "head": "release-#{version}",
+    "base": "master"
+  }.to_json
+  res = post("/repos/#{owner}/#{repo}/pulls", body)
+  raise "Creating release PR failed (#{res.code})" unless res.kind_of? Net::HTTPSuccess
+end
+
+def can_auth?
+  !ENV["GH_RELEASE_TOKEN"].nil?
+end
+
+args = ARGV.dup
+dry_run = false
+if args.include?("--dry-run")
+  dry_run = true
+  args.delete '--dry-run'
+end
+
+if args.include?("--no-warn")
+  $no_warn = true
+  args.delete '--no-warn'
+end
+
+if args.size < 1
+  $stderr.puts "Usage: release [--dry-run] <version>"
+  exit 1
+end
+
+begin
+  version = Gem::Version.new(args[0])
+rescue ArgumentError
+  $stderr.puts "Error parsing version #{args[0]}"
+  exit 1
+end
+
+release_changes = []
+release_a = false
+if dry_run
+  if can_auth?
+    release_changes = beautify_changes(changelog, GH_OWNER, GH_REPO)
+    release_a = release_available?(GH_OWNER, GH_REPO, "v#{version}")
+    puts "Existing release: #{release_a}"
+  end
+  puts "New version: #{version}"
+  puts "Owner: #{GH_OWNER}"
+  puts "Repo: #{GH_REPO}"
+  puts "Author: #{GH_AUTHOR}"
+  puts "Token: #{ENV['GH_RELEASE_TOKEN'] && "set" || "unset"}"
+  if can_auth?
+    puts "Changelog:"
+    release_changes.each { |c| puts "  * #{c}"}
+  end
+  exit
+end
+
+if release_a
+  $stderr.puts "Release #{version} already exists."
+  exit 1
+end
+
+`git fetch --quiet origin --prune`
+branches = `git branch --all | grep release-#{version}$`
+if !branches.empty?
+  $stderr.puts "Release branch release-#{version} already exists."
+  $stderr.puts "Branches found:"
+  branches.each_line { |l| puts "* #{l.strip.chomp}" }
+  exit 1
+end
+
+puts "Bumping version to #{version}"
+bump_version(version)
+
+puts "Updating changelog"
+update_changelog release_changes, DEB_PKG_NAME, version, GH_AUTHOR, GH_OWNER, GH_REPO
+
+puts "Creating release"
+release_title = "GitHub Enterprise Backup Utilities v#{version}"
+release_body = "Includes general improvements, bug fixes and support for GitHub Enterprise v#{version}"
+release_changes.each do |c|
+  release_body += "\n* #{c}"
+end
+create_release "v#{version}", "master", GH_OWNER, GH_REPO, release_title, release_body
+
+puts "Creating and publishing the release branch"
+push_release_branch(version, release_changes)
+create_release_pr(version, GH_OWNER, GH_REPO, release_body)
+puts "Released!"