cross-platform git pre-commit hook for puppet repos

pre-commit

#!/usr/bin/env ruby

# An example cross-platform (Linux, Windows, Mac, etc.)
# pre-commit hook script to verify what is about to be committed.
# Called by "git commit" with no arguments.  The hook should
# exit with non-zero status after issuing an appropriate message if
# it wants to stop the commit.

# To enable this hook:
# - save this file as <path-to-git-clone>/.git/hooks/pre-commit
# - mark file as executable

# Current checks:
# - ruby syntax
# - erb (template) syntax
# - puppet syntax
# - puppet style
# - unresolved merge conflicts
# - yaml (just check if well-formed)

# assume everything is good; override as things go bad
rc = 0

dependencies = [
  'puppet',
  'puppet-lint',
  'open3',
]

dependencies.each do |d|
  begin
    require d
  rescue
    rc = 1
    puts "Missing dependency: #{d}"
  end
end

# create a reusable puppet parser object for checking syntax
parser = Puppet::Parser::Parser.new('')

# create a reusable puppet-lint object for checking style
linter = PuppetLint.new
begin
  linter.quiet = true # suppress normal output
rescue
  rc = 1
  puts 'Oops. Need puppet-lint version from https://github.com/rodjek/puppet-lint/pull/124'
end

if rc != 0
  puts 'Bailing before I hurt myself'
  exit(rc)
end

if `git rev-parse --quiet --verify HEAD`.empty?
  # Initial commit: diff against an empty tree object
  treeish = '4b825dc642cb6eb9a060e54bf8d69288fbee4904'
else
  treeish = 'HEAD'
end

# get list of staged files
filenames = `git diff-index --diff-filter=AM --name-only --cached #{treeish}`.split(/\n/)

filenames.each do |f|
  # get file content from index, not from workdir
  # (but skip to next filename if this commit removes the file)
  (content = `git cat-file -p :0:#{f}`).empty? && next

  # look for unresolved merge conflicts
#  content.split(/\n/).each do |line|
#    if /^<<<<<<<|^>>>>>>>|^=======$/.match(line)
#      rc = 1
#      puts "ERROR: #{f} appears to have unresolved merge conflicts"
#    end
#  end

  # check for well-formed yaml
  if /\.yaml$/.match(f)
    begin
      YAML.load(content)
    rescue ArgumentError, Psych::SyntaxError
      rc = 1
      puts "ERROR: #{f} is not well-formed YAML"
    end
  end

  # Ruby (.rb) and template (.erb) files
  if /\.e{0,1}rb$/.match(f)
    if /\.erb$/.match(f)
      # convert content from erb to ruby
      content = ERB.new(content, nil, '-').src
    end
    begin
      # check ruby syntax
      Open3.popen3('ruby -Ku -c') do |stdin, stdout, stderr|
        stdin.puts(content)
        stdin.close
        output = (stdout.readline rescue '')
        unless /^Syntax OK$/.match(output)
          rc = 1
          error = (stderr.readline rescue '')
          puts "ERROR: #{f} #{error}"
        end
      end
    rescue => except
      rc = 1
      puts "ERROR: #{except.message}"
    end
  end

  # puppet (.pp) files
  if /\.pp$/.match(f)
    begin
      # check puppet syntax
      parser.parse(content)

      # check puppet style, but only if parser didn't raise exception
      linter.run_virtual(f, content)
      if linter.errors?
        rc = 1
        puts "#{f}: #{linter.statistics[:error]} puppet-lint errors (fatal)"
      end
    rescue => except
      # if we're here, puppet parser found bad syntax
      rc = 1
      puts "ERROR: #{f} #{except.message}"
    end
  end
end

# if we exit non-zero, git will abort the commit
exit(rc)