Add logging to forward-merge script

Add some logging to aid with development.

git/hooks/forward-merge

@@ -2,6 +2,10 @@
 require 'json'
 require 'net/http'
 require 'yaml'
+require 'logger'
+
+$log = Logger.new(STDOUT)
+$log.level = Logger::WARN
 
 class ForwardMerge
   attr_reader :issue, :milestone, :message, :line
@@ -14,21 +18,41 @@ class ForwardMerge
 end
 
 def find_forward_merge(message_file)
-  rev=`git rev-parse -q --verify MERGE_HEAD`
+  $log.debug "Searching for for forward merge"
+  rev=`git rev-parse -q --verify MERGE_HEAD`.strip
+  $log.debug "Found #{rev} from git rev-parse"
   return nil unless rev
   message = File.read(message_file)
   message.each_line do |line|
+    $log.debug "Checking #{line} for message"
     match = /^(?:Fixes|Closes) gh-(\d+) in ([\d\.]+(?:(?:M|RC)\d)?)$/.match(line)
     if match then
       issue = match[1]
       milestone = match[2]
+      $log.debug "Matched reference to issue #{issue} in milestone #{milestone}"
       return ForwardMerge.new(issue, milestone, message, line)
     end
   end
+  $log.debug "No match in merge message"
   return nil
 end
 
+def get_issue(username, password, repository, number)
+  $log.debug "Getting issue #{number} from GitHub repository #{repository}"
+  uri = URI("https://api.github.com/repos/#{repository}/issues/#{number}")
+  http = Net::HTTP.new(uri.host, uri.port)
+  http.use_ssl=true
+  request = Net::HTTP::Get.new(uri.path)
+  request.basic_auth(username, password)
+  response = http.request(request)
+  $log.debug "Get HTTP response #{response.code}"
+  return JSON.parse(response.body) unless response.code != '200'
+  puts "Failed to retrieve issue #{number}: #{response.message}"
+  exit 1
+end
+
 def find_milestone(username, password, repository, title)
+  $log.debug "Finding milestone #{title} from GitHub repository #{repository}"
   uri = URI("https://api.github.com/repos/#{repository}/milestones")
   http = Net::HTTP.new(uri.host, uri.port)
   http.use_ssl=true
@@ -37,25 +61,15 @@ def find_milestone(username, password, repository, title)
   response = http.request(request)
   milestones = JSON.parse(response.body)
   milestones.each do |milestone|
+    $log.debug "Considering #{milestone['title']}"
     return milestone['number'] if milestone['title'] == title
   end
   puts "Milestone #{title} not found"
   exit 1
 end
 
-def get_issue(username, password, repository, number)
-  uri = URI("https://api.github.com/repos/#{repository}/issues/#{number}")
-  http = Net::HTTP.new(uri.host, uri.port)
-  http.use_ssl=true
-  request = Net::HTTP::Get.new(uri.path)
-  request.basic_auth(username, password)
-  response = http.request(request)
-  return JSON.parse(response.body) unless response.code != '200'
-  puts "Failed to retrieve issue #{number}: #{response.message}"
-  exit 1
-end
-
 def create_issue(username, password, repository, original, title, labels, milestone, milestone_name, dry_run)
+  $log.debug "Finding forward-merge issue in GitHub repository #{repository} for '#{title}'"
   uri = URI("https://api.github.com/repos/#{repository}/issues")
   http = Net::HTTP.new(uri.host, uri.port)
   http.use_ssl=true
@@ -73,23 +87,32 @@ def create_issue(username, password, repository, original, title, labels, milest
     return "dry-run"
   end
   response = JSON.parse(http.request(request).body)
+  $log.debug "Created new issue #{response['number']}"
   return response['number']
 end
 
+$log.debug "Running forward-merge hook script"
 message_file=ARGV[0]
+
 forward_merge = find_forward_merge(message_file)
 exit 0 unless forward_merge
+
+$log.debug "Loading config from ~/.spring-boot/forward_merge.yml"
 config = YAML.load_file(File.join(Dir.home, '.spring-boot', 'forward-merge.yml'))
 username = config['github']['credentials']['username']
 password = config['github']['credentials']['password']
 dry_run = config['dry_run']
 repository = 'spring-projects/spring-boot'
+
 existing_issue = get_issue(username, password, repository, forward_merge.issue)
 title = existing_issue['title']
 labels = existing_issue['labels'].map { |label| label['name'] }
 labels << "status: forward-port"
+$log.debug "Processing issue '#{title}'"
+
 milestone = find_milestone(username, password, repository, forward_merge.milestone)
 new_issue_number = create_issue(username, password, repository, forward_merge.issue, title, labels, milestone, forward_merge.milestone, dry_run)
+
 puts "Created gh-#{new_issue_number} for forward port of gh-#{forward_merge.issue} into #{forward_merge.milestone}"
 rewritten_message = forward_merge.message.sub(forward_merge.line, "Closes gh-#{new_issue_number}\n")
 File.write(message_file, rewritten_message)