@@ -1,5 +1,7 @@ 1.0.5 * Added erb: a file task that creates a file form an ERB template. +* The write and update file methods now perform atomic writes (create +temporary file, rename to desired path). 1.0.4 (2009-11-4) * When used with -U option and no other argument, necktie command updates the CHANGELOG @@ -208,4 +208,8 @@ Includes Session, created by Ara T. Howard and released under the Ruby License http://raa.ruby-lang.org/project/session http://www.codeforpeople.com/lib/ruby/session +Atomic file write adapted from Rails. + +ERB task adapted from Luke Bayes http://gist.github.com/215270. + Developed for managing EC2 instances for http://apartly.com README.rdoc @@ -1,43 +1,69 @@ -module Necktie::Files - # Return the contents of the file (same as File.read). - def read(name) - File.read(name) - end +require "tempfile" - # Writes contents to a new file, or overwrites existing file. - # Takes string as second argument, or yields to block. For example: - # write "/etc/mailname", "example.com" - # write("/var/run/bowtie.pid") { Process.pid } - def write(name, contents = nil) - contents ||= yield - File.open name, "w" do |f| - f.write contents +module Necktie + module Files + # Return the contents of the file (same as File.read). + def read(name) + File.read(name) end - end - # Append contents to a file, creating it if necessary. - # Takes string as second argument, or yields to block. For example: - # append "/etc/fstab", "/dev/sdh /vol xfs\n" unless read("/etc/fstab")["/dev/sdh "] - def append(name, contents = nil) - contents ||= yield - File.open name, "a" do |f| - f.write contents + # Writes contents to a new file, or overwrites existing file. Takes string + # as second argument, or yields to block. For example: + # + # write "/etc/mailname", "example.com" + # write("/var/run/bowtie.pid") { Process.pid } + # + # This method performs an atomic write using TMPDIR or (/tmp) as the + # temporary directory and renaming the file over to the new location. + # Ownership and premission are retained if replacing existing file. + def write(name, contents = nil) + contents ||= yield + temp = Tempfile.new(File.basename(name)) + temp.write contents + temp.close + + begin + # Get original file permissions + stat = File.stat(name) + rescue Errno::ENOENT + # No old permissions, write a temp file to determine the defaults + stat_check = File.join(File.dirname(name), ".permissions_check.#{Thread.current.object_id}.#{Process.pid}.#{rand(1000000)}") + File.open(stat_check, "w") { } + stat = File.stat(stat_check) + File.unlink stat_check + end + + # Overwrite original file with temp file + File.rename(temp.path, name) + + # Set correct permissions on new file + File.chown stat.uid, stat.gid, name + File.chmod stat.mode, name + end + + # Append contents to a file, creating it if necessary. Takes string as + # second argument, or yields to block. For example: + # append "/etc/fstab", "/dev/sdh /vol xfs\n" unless read("/etc/fstab")["/dev/sdh "] + def append(name, contents = nil) + contents ||= yield + File.open name, "a" do |f| + f.write contents + end end - end - # Updates a file: read contents, substitue and write it back. - # Takes two arguments for substitution, or yields to block. - # These two are equivalent: - # update "/etc/memcached.conf", /^-l 127.0.0.1/, "-l 0.0.0.0" - # update("/etc/memcached.conf") { |s| s.sub(/^-l 127.0.0.1/, "-l 0.0.0.0") } - def update(name, from = nil, to = nil) - contents = File.read(name) - if from && to - contents = contents.sub(from, to) - else - contents = yield(contents) + # Updates a file: read contents, substitue and write it back. Takes two + # arguments for substitution, or yields to block. These two are equivalent: + # update "/etc/memcached.conf", /^-l 127.0.0.1/, "-l 0.0.0.0" + # update("/etc/memcached.conf") { |s| s.sub(/^-l 127.0.0.1/, "-l 0.0.0.0") } + def update(name, from = nil, to = nil) + contents = File.read(name) + if from && to + contents = contents.sub(from, to) + else + contents = yield(contents) + end + write name, contents end - write name, contents end end lib/necktie/files.rb @@ -1,20 +1,22 @@ require "rubygems/dependency_installer" -module Necktie::Gems - # Installs the specified gem, if not already installed. First argument is the - # name of the gem, or file containing the gem. Second argument is version requirement. - # For example: - # install_gem "unicorn", "~>0.93" - # - # Dir["gems/*.gem"].each do |gem| - # install_gem gem - # end - def install_gem(name, version = nil) - installer = Gem::DependencyInstaller.new - spec = installer.find_spec_by_name_and_version(name, version).first.first - if Gem::SourceIndex.from_installed_gems.find_name(spec.name, spec.version).empty? - puts " ** Installing the gem #{spec.name} #{spec.version}" - installer.install name, version +module Necktie + module Gems + # Installs the specified gem, if not already installed. First argument is the + # name of the gem, or file containing the gem. Second argument is version requirement. + # For example: + # install_gem "unicorn", "~>0.93" + # + # Dir["gems/*.gem"].each do |gem| + # install_gem gem + # end + def install_gem(name, version = nil) + installer = Gem::DependencyInstaller.new + spec = installer.find_spec_by_name_and_version(name, version).first.first + if Gem::SourceIndex.from_installed_gems.find_name(spec.name, spec.version).empty? + puts " ** Installing the gem #{spec.name} #{spec.version}" + installer.install name, version + end end end end lib/necktie/gems.rb 7b875ed0098af3c76a6d790df74df2787cd1637f Assaf Arkin assaf@labnotes.org http://github.com/assaf/necktie/commit/111de47350fae6ef067586ec3978b8a2ec320da3 111de47350fae6ef067586ec3978b8a2ec320da3 2009-11-06T12:17:41-08:00 2009-11-06T12:17:41-08:00 The write and update file methods now perform atomic writes (create temporary file, rename to desired path). 0ff600b4520342e3a466175d5826fdc6319a06c8 Assaf Arkin assaf@labnotes.org